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Comparative bioequivalence studies with Estradot® and Menorest® transdermal systems
Maturitas 46 (2003) 187 /198 www.elsevier.com/locate/maturitas
Comparative bioequivalence studies with Estradot† and Menorest† transdermal systems M. Hossain a,1, E. Quebe-Fehling a, T. Sergejew a, G. Schmidt a, A. Skerjanec a,*, A. Cohen b,c,2, L. Krinsky d,3, Patricia Ibarra de Palacios a,1 b
a Novartis Pharma AG, Basel, Switzerland Peninsular Testing Corporation, 20215 NW 2nd Avenue, Suite 3, Miami, FL 33169, USA c Clinical Testing Corporation Research Unit, Opa Locka, FL 33056, USA d South Florida Bioavailability Clinic, Miami, FL, USA
Received 16 January 2002; received in revised form 24 March 2003; accepted 17 April 2003
Abstract Objectives: To compare the relative bioavailability of Estradot† , a small size, new generation estradiol transdermal system (ETS) to Menorest† , in healthy postmenopausal women. Methods: In two open-label, single center, randomized, crossover, bioequivalence studies, healthy postmenopausal women aged 40 /65 years received treatment with all the test regimens. In Study 1 (single-dose study), patients wore 5 cm2 (50 mg/day), 10 cm2 (100 mg/day) Estradot and 29 cm2 (100 mg/day) Menorest for 84 h. In Study 2 (multiple-dose study), patients wore a regimen of four consecutive treatments with a 5 cm2 (50 mg/day) new generation patch, Estradot and a 14.5 cm2 (50 mg/day) patch, Menorest. Blood samples were drawn at various time-points in both studies. Estradiol and estrone serum levels were determined by gas chromatography/mass spectrometry or radioimmunoassay methods. Skin irritation (erythema and edema), patch adherence and local skin reaction were assessed following patch removal. Results: In Study 1, baselineuncorrected Cmax for estradiol for Estradot 50 and 100 mg/day and Menorest 100 mg/day was 54.8, 106.2 and 101.6 pg/ ml, respectively, and Cmax for estrone was 75.6, 97.0 and 98.3 pg/ml, respectively. In Study 2, the baseline-uncorrected mean maximum serum concentration (Cmax) for estradiol for Estradot 50 mg/day and Menorest 50 mg/day patches was 56.7 and 52.7 pg/ml, respectively, and Cmax for estrone was 41.7 and 41.3 pg/ml, respectively. No significant skin irritation was observed in either study, but Estradot caused less skin irritation than Menorest. Conclusions: Estradot produced comparable serum concentrations of estradiol and estrone and caused less skin irritation than Menorest. # 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Transdermal; Estradiol; Matrix; Bioequivalence; HRT * Corresponding author. Present address: Novartis Pharmaceuticals, 1 Health Plaza, East Hanover, NJ 07936, USA. Tel.: /1-862778-6508; fax: /1-973-781-8865. E-mail addresses: [email protected] (A. Skerjanec), [email protected], [email protected] (A. Cohen), [email protected] (L. Krinsky), [email protected] (P. Ibarra de Palacios). 1 Tel.: /41-61-324-7540; fax: /41-61-324-5218. 2 Tel.: /1-305-621-4533; fax: /1-305-621-4534. 3 Tel.: /1-305-895-0304; fax: /1-305-895-8616. 0378-5122/03/$ - see front matter # 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/S0378-5122(03)00190-7
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1. Introduction Several studies have demonstrated that climacteric symptoms associated with the decline in endogenous estrogen in menopausal women can be alleviated by hormone replacement therapy (HRT) [1]. The beneficial effects of HRT are well established [2] and HRT is now an accepted treatment for the relief and prevention of menopausal symptoms such as vasomotor disturbances (hot flushes and sweating), urogenital atrophy and sleep disturbance. This treatment can also provide protection against other aetiologies [1,3 /7]. Oral treatment with natural or synthetic estradiol is a well-known and accepted method for treating estrogen deficiencies, but this method has its disadvantages. Orally administered estradiol is rapidly metabolized in the intestinal tract and liver to estrone and gluconuride conjugates which are excreted in bile or urine [8]. This degradation reduces the bioavailability of the administered estradiol [9,10] and leads to higher circulating levels of estrone than estradiol. Higher doses are, therefore, needed to achieve therapeutic serum concentrations of estradiol [8]. In contrast, the skin metabolizes estradiol only to a small extent and transdermal HRT systems offer distinct advantages over oral therapy, since estradiol is delivered directly into the bloodstream and the hepatic first-pass effect is avoided. Transdermal administration of estradiol produces therapeutic levels of estradiol with lower circulating levels of estrone and estrone conjugates and a more physiological estradiol: estrone ratio is achieved [11,12]. Smaller total doses are, therefore, needed with transdermal therapy than with oral therapy and, because estradiol has a relatively short halflife, transdermal administration of estradiol allows a rapid decline in blood levels after the system is removed. A study of the long-term effects of HRT has determined that the positive effects of transdermal HRT are more marked than those of oral therapy [13]. Transdermal therapy provides constant steady-state drug delivery, physiological estradiol levels and avoids the first-pass metabolism in the liver. Transdermal delivery systems for estradiol have been shown to be clinically effective in relieving menopausal symptoms and, further-
more, are non-invasive, easy to use and well accepted by patients. A new estradiol transdermal system (ETS), Estradot, has been developed which consists of estradiol contained in a multipolymeric adhesive platform using a patented DOT MatrixTM technology. Delivery optimized thermodynamics (DOT) is a new, highly efficient class of diffusion-based drug-in-adhesive technology that delivers more drug through less patch surface area without using irritating enhancers and with excellent adhesion. The drug is blended into microscopic pockets uniformly dispersed throughout the patch’s drug/ adhesive layer. This high-concentration gradient between the drug pocket and the skin optimizes the diffusion of drug from the patch, through the skin into the bloodstream. DOT patches are smaller, less irritating and more adherent than competitive reservoir-based and ordinary drug-inadhesive patches, which should offer better wear properties to the patient and result in better compliance. The surface area of the transdermal matrix patch determines the level of in vivo delivery of estradiol to the systemic circulation and ranges from 2.5 cm2, which delivers 25 mg/day, to 10 cm2 which delivers 100 mg/day, which would make this product the smallest of any of the currently approved products. Dosages can, therefore, be tailored to the needs of a specific patient. The smaller surface area of these new transdermal patches means that they are more likely to be acceptable, at the same time providing serum estradiol concentrations comparable with patches having a much larger surface area. Two independent studies were conducted where the primary objective was to determine the bioavailability of estradiol from the new multipolymeric matrix patches in healthy menopausal women. In the initial pilot clinical study (Study 1), Estradot patches with a surface area of 5 and 10 cm2, which were expected to release approximately 50 and 100 mg/day estradiol, respectively, were compared with Menorest, a currently marketed patch with a surface area of 29 cm2 and an expected delivery of 100 mg/day estradiol. In subsequent study (Study 2), the 5 cm2 multipolymeric matrix patch, Estradot (marketed as VivelleDotTM in the US) (50 mg/day estradiol
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release) was compared with a currently marketed transdermal estradiol patch having a surface area of 14.5 cm2 delivering 50 mg/day (marketed as Menorest in Europe or as VivelleTM in the US). In both studies, the secondary objective was the evaluation of the wear and irritation properties of these transdermal systems. The local irritation and sensitization of Menorest are well documented [8,14/16] and this was, therefore, considered to be an acceptable comparator.
2. Materials and methods 2.1. Patients Twelve patients were enrolled for Study 1 and 32 patients for Study 2. The populations for both studies were healthy, non-smoking, postmenopausal women (naturally or surgically induced) between the ages of 40 and 65 years and weighing between 108 and 187 pounds (lbs). Patients were in good health, as determined from a medical history, physical examination including pelvic examination, Pap smear, mammogram, electrocardiogram and routine laboratory safety tests. Postmenopausal status in patients was confirmed, based on a serum estradiol level 5/20 pg/ml and a serum follicle stimulating hormone (FSH) level ]/50 mIU/ml, measured from blood samples obtained during the screening examination. Supine blood pressure (BP), heart rate (HR) and respiratory rate (RR) were taken immediately prior to each treatment and then at 2 and 4 h after the patch application. Throughout the studies, patients were continuously observed and questioned for the occurrence of any adverse events. Written consent was obtained from all participants prior to entry into the study. 2.2. Method 2.2.1. Study 1 This was an open-label, single-center, singledose, randomized, three-treatment, three-period crossover bioavailability study. Each patient was randomly assigned to a crossover treatment sequence and received treatment with each of the
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three test regimens. Each transdermal patch was applied to clean, dry, non-oily, non-irritated skin on the abdomen, below the waistline, for 84 h (3.5 days). After removal of each patch there was a 7day washout period between treatments. The three treatments were A: Estradot 5 cm2 new generation patch delivering approximately 50 mg/day, B: Estradot 10 cm2 new generation patch delivering approximately 100 mg/day and C, Menorest 29 cm2 existing patch delivering approximately 100 mg/ day. The latter was considered the reference patch for statistical analysis purposes. Blood samples (10 ml) for determination of serum concentration of estradiol and estrone, were taken 24 h prior to dosing (/24) and immediately prior to each treatment (0 h), then at 2, 4, 8, 12, 24, 36, 48, 60, 72, 84, 96 and 108 h after patch application. Blood collection, treatment and storage were as described in Study 1. Serum levels of estradiol and estrone were determined using a validated radioimmunoassay method. The analytical methods had a limit of quantification (LOQ) for estradiol of 6.46 pg/ml and an LOQ for estrone of 10.7 pg/ml in serum. The two pre-dose serum levels were used to calculate mean baseline estradiol and estrone concentrations. The estradiol content of worn patches after their removal from patients was assayed by HPLC and was used to calculate the apparent dose delivered by the three treatments. Adherence of the transdermal patches was evaluated at 2, 4, 8 and then every 12 h after application. After the removal of the patch, the application site was examined for any evidence of adhesive residue remaining on the skin site. The application site was examined for any evidence of local skin irritation (erythema and edema) approximately 1 min after patch removal and, again, 24 h after patch removal and the observations recorded. Patients completed a questionnaire in which they described their overall impression of the wear characteristics of the patch. Safety was monitored by means of pre- and post-treatment physical examinations. 2.2.2. Study 2 This was an open-label, single-center, multipledose, randomized, two-treatment, two-period,
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crossover, bioavailability study. Each patient was randomly assigned to a crossover treatment sequence and received treatment with each of the two test regimens. Each transdermal patch was applied to clean, dry, non-oily, non-irritated skin on the abdomen, below the waistline, for 84 h (3.5 days) for 4 consecutive wear periods, making a total of 14 days for each treatment. There was a 7day washout period between treatments. Treatment A was Estradot 5 cm2 new generation patch and treatment B was Menorest 14.5 cm2 existing patch, each delivering approximately 50 mg/day. The latter was considered the reference patch for statistical analysis purposes. Blood samples (7 ml) for determination of serum concentration of estradiol and estrone, were taken 36 h (/36) and 12 h (/12) prior to application of the first patch. Additional blood samples were drawn immediately prior to removal (84 h) at the end of the first, second and third wear periods. The third 84-h sample was also the 0-h sample for the fourth wear period. Following application of the fourth patch, blood samples were collected at 2, 4, 6, 8, 10, 12, 18, 24, 30, 36, 42, 48, 60, 72, 84, 88, 92 and 96 h. Venous blood was collected into red-top evacuated glass tubes which contained no preservatives or anticoagulants. The blood was allowed to clot at room temperature for at least 10 min, refrigerated for 2 h and the serum was then separated by centrifugation at 3000 rpm in a refrigerated centrifuge at 5 8C for 15 min. The supernatant was transferred into plastic specimen transfer vials and stored at /20 8C until time of assay for estradiol and estrone. Serum levels of estradiol and estrone were determined by a validated gas chromatography/mass spectrometry (GC/MS) method with an LOQ for estradiol of 2.5 pg/ml and an LOQ for estrone of 5.0 pg/ml in serum. The /36 and /12 h pre-dose serum levels were used to calculate mean baseline estradiol and estrone concentrations. The estradiol content of worn patches after removal from the patients was assayed by HPLC to determine the apparent clinical dose delivered by the two ETS. The apparent dose values were calculated from residual estradiol extracted from the transdermal systems after 84 h of wear by the patients in these studies, subtracted from a control value (the mean potency
of the lot used): Apparent dose /initial potency / residual potency. This parameter is known as the apparent dose because it is not possible to guarantee that all of the drug lost from a transdermal system is actually absorbed [17]. Adherence of the transdermal patches was evaluated at 2, 4, 8 and 84 h after the first, second and third wear periods. A replacement patch was provided to patients in the event of patch loss and the patients were instructed to record application time and dates for any replacement patches. During the fourth wear period, patch adherence was checked at 2, 4, 8, 12, then every 12 h until removal. Findings were recorded as an estimate of the percentage of the patch surface in contact with the skin, according to a 5-point scale of 0/4, where 0/patch adhered /90% (completely on); 1 / patch adhered 75 /90% (edges lifting off or center raised); 2 /50 /75% (half off); 3 /patch adhered B/50% (just hanging on); and 4 /patch not present on skin. Immediately following removal of the patch, the application site was examined for any evidence of adhesive residue remaining on the skin and graded on a 4-point scale of 0/3, where 0/none; 1/light; 2/medium; and 3 /heavy. Approximately 1 min and 1 and 12 h after patch removal, the application site was examined for evidence of local skin irritation. Topical irritation was graded according to a 6-point scale of 0 /5 where 0 /no erythema; 1 /‘ring’ erythema, ring limited to perimeter of the contact site; 2 /(mild) pink, uniform erythema with or without edema covering most of the contact site; 3/(moderate) pink-red erythema with or without edema uniform in the entire contact site; 4/(marked) bright-red erythema with or without edema, petechiae or papules; and 5/(severe) deep-red erythema with or without edema, vesiculation or weeping, severe erythema (beet-redness to slight eschar formation, injuries in depth). 2.2.3. Pharmacokinetic analysis Pharmacokinetic parameters were calculated for baseline-uncorrected estradiol and estrone, for each patient and each treatment, using ‘PKCALC’, software for non-compartmental pharmacokinetic data analysis [18]. In Study 1, the following pharmacokinetic parameters were calculated
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from the serum data. Cmax, Tmax, AUC0 84 /area under the concentration /time curve from 0 to 84 h (time during transdermal estradiol patch application) calculated using the linear trapezoidal rule (pg h/ml), AUC0 108 /area under the concentration /time curve from time 0 to the last serum value measured, Clast calculated using the linear trapezoidal rule, (pg h/ml), AUC0 / AUC calculated using the linear trapezoidal rule from 0 time to the time of the last measurable concentration and extrapolated to infinity using Clast/ke to calculate the residual area from Clast to infinity (pg h/ml). AUC0 , ke and t1/2 were calculated for estradiol only. In Study 2, the following pharmacokinetic parameters were calculated from the steady-state serum data; Cmax, maximum serum concentration (pg/ml), Tmax, time to maximum plasma concentration (h), Cmin, the steady-state trough serum concentration (84-h), % fluctuation /[100(Cmax / Cmin)/Cmin], AUCss, area under the serum concentration curve during a dosing interval at steady state. This is equivalent to AUC0 84, area under the concentration /time curve calculated from 0 to 84 h during the fourth wear period (time of ETS application). Values were calculated using the linear trapezoidal rule (pg h/ml). AUC0 96, area under the concentration /time curve from time 0 to the last serum value measured after last dose (fourth wear period), calculated using the linear trapezoidal rule from 0 to 96 h, (pg h/ml), ke, elimination rate constant, from loge, linear regression of points using the terminal linear portion of the logarithm transformed serum estradiol concentrations beginning with the 84-h sample collected at the time of patch removal, (per h). The parameter, ke, was calculated for estradiol only, t1/2, apparent terminal elimination half-life of drug in serum, (h). The t1/2 was calculated from the individual ke values using the relationship t1/2 / loge 2/ke. 2.2.4. Statistical analysis In both studies, an analysis of variance (ANOVA) of the pharmacokinetic parameters was calculated. The sequence effect was tested against patient within sequence. In Study 1, a Tukey multiple comparisons procedure was used to test
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pairwise differences between treatments. The two one-sided tests procedure and a 20% equivalence criterion was used to evaluate the equivalence between the Estradot 10 cm2 and the reference Menorest 29 cm2 patches. In Study 2, Type III sums of squares were used throughout. Two one-sided tests and an 80 /125% equivalence criterion were performed for the logtransformed parameters (Cmax, Cmin, AUC0 84, AUC0 96) using the Estradot 5 cm2 as test and Menorest 14.5 cm2 patch as the reference formulation. To demonstrate that steady state levels were obtained during the multiple-dosing regimen, the 84-h values obtained after the second wear period were compared with the 84-h values after the fourth wear period. For both of these wear periods, the 84-h samples were collected at 20:00 h to minimize the potential confounding effect of circadian rhythms.
3. Results All patients (12 in Study 1 and 32 in Study 2) completed their respective study. In Study 1, analysis of serum estradiol pharmacokinetic parameters suggested that one patient who had a treatment ratio higher than those of the other 11 patients was an outlier in this study and data from this patient was, therefore, excluded from the analyzes. In Study 2, two patients were excluded from the pharmacokinetic data analysis due to errors in dosing */one patient lost her patch during treatment period 1, wear period 1 and inadvertently applied the release liner from the back-up patch, and one patient inadvertently received treatment with the Estradot 50 mg/day patch instead of the Menorest 50 mg/day patch during treatment period 1, wear period 4. These two patients were included in the safety analysis. Baseline demographics for patients in both studies are shown in Table 1. 3.1. Pharmacokinetic data The results of the pharmacokinetic analysis for estradiol are summarized in Tables 2 and 3 for Study 1 and Study 2, respectively, and mean
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Table 1 Baseline demographics for patients
Study 1 (n/11) Range (min and max) Study 2 (n/ 32)3 Range (min and max)
Age (year) mean (S.D.)
Weight (lb) mean (S.D.)
Height (in.) mean (S.D.)
55.8 (6.7) 40 /63 55.8 (5.1) 43 /65
146.0 (23) 111 /182 151.2 (20.1) 108 /187
63.1 (3.2) 58 /68 63.8 (2.2) 60 /68
estradiol serum concentration /time profiles for these studies are shown in Figs. 1 and 2, respectively. The pharmacokinetic analysis for estrone is summarized in Tables 4 and 5 for Study 1 and Study 2, respectively, and mean estrone serum concentration /time profiles are shown in Figs. 3 and 4, respectively. The mean apparent dose values calculated from residual estradiol extracted from the transdermal systems after 84 h of wear by the patients in these studies are included in Tables 2 and 3 for Study 1 and Study 2, respectively. Data are expressed as mean and standard deviation. The statistical analysis, shown as Two one-sided tests procedure confidence intervals for Study 1 and Study 2 are presented in Tables 6 and 7, respectively. Elimination rate constants and serum halflife values could not be determined for estrone in either study due to the lack of an observable elimination phase. The estradiol elimination rate
constant, ke, was calculated from the terminal linear portion of the logarithmic serum concentration versus time plot, beginning with samples collected at the time of patch removal (84 h) and is shown in Table 2 for the 5, 10 and 29 cm2 ETS in Study 1 and in Table 3 for the 5 and 14.5 cm2 ETS in Study 2.
3.1.1. Clinical observations Seven of the 12 patients (58%) enrolled in Study 1 and five of the 32 patients (16%) enrolled in Study 2 reported at least one adverse event during the treatment. All incidences except one were rated as mild in severity and were resolved during the study. A single episode of diarrhea was moderate in severity. The most frequently reported event was headache (five reports in Study 1; three in Study 2). Nausea, neck pain, leg pain, constipa-
Table 2 Mean pharmacokinetic parameters for estradiol obtained after treatments with three different transdermal estradiol systems: Estradot 5 cm2 (50 mg/day) and 10 cm2 (100 mg/day) new generation patches and Menorest 29 cm2 (100 mg/day) existing patch, in Study 1 (n/ 11) Parameter
5 cm2 ETS (50 mg/day) Estradot mean (S.D.)
10 cm2 ETS (100 mg/day) Estradot mean (S.D.)
29 cm2 ETS (100 mg/day) Menorest mean (S.D.)
Cmax (pg/ml) Tmax (h) AUC0 84 (pg h/ ml) AUC0 108 (pg h/ ml) AUC0 (pg h/ ml) ke (per h) t1/2 (h)
54.8 (13.9) 34.9 (19.5) 3569.4 (763.5)
106.2 (35.9) 29.5 (19.6) 6029.5 (2384.6)
101.6 (39.1) 27.3 (20.1) 6068.5 (1762.2)
3677.8 (1032.0)
6408.6 (2515.7)
6497.8 (1788.0)
3969.6 (860.2)
6971.8 (2190.2)
6590.1 (1787.8)
0.1274 (0.0787) 6.88 (2.92)
0.1249 (0.0823) 7.69 (4.14)
0.1863 (0.1453) 5.94 (3.68)
0.23 (0.06) 0.066 (0.02)
0.46 (0.20) 0.131 (0.06)
0.53 (0.11) 0.151 (0.03)
Apparent dose (mg/unit) (mg/day)
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Table 3 Mean pharmacokinetic parameters for estradiol obtained after treatments with two different transdermal estradiol systems: Estradot 5 cm2 (50 mg/day) new generation patch and Menorest 14.5 cm2 (50 mg/day) existing patch, in Study 2 (n/30) Parameter
5 cm2 ETS Estradot (50 mg/day) mean (S.D.)
14.5 cm2 ETS Menorest (50 mg/day) mean (S.D.)
Cmax (pg/ml) Tmax (h) Cmin (pg/ml) % Fluctuation AUC0 84 (pg h/ml) AUC0 96 (pg h/ml) ke (per h) t1/2 (h)
56.7 (30.7) 30.7 (15.6) 28.1 (19.5) 158.0 (190.8) 3088 (1721)
52.7 (20.0) 22.0 (13.5) 29.4 (12.3) 89.2 (59.4) 2886 (1147)
3268 (1865)
3051 (1191)
0.138 (0.079) 7.7 (7.1)
0.132 (0.056) 6.3 (2.7)
Apparent dose (mg/unit) 0.18 (0.05) (mg/day) 0.05 (0.01)
0.19 (0.09) 0.05 (0.02)
tion, diarrhea, dry cough, back pain and myalgia were also reported.
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3.1.2. Transdermal system assessments All the transdermal systems adhered well to the volunteers throughout each of the 84-h application periods. In Study 2, all Estradot 5 cm2 patches scored 0, i.e. /90% (completely on) in the first 12 h of wear periods 1, 2 and 3. In the same time period, four Menorest 14.5 cm2 patches scored 1 (75 /90% on). The error in dosing of one patient meant that 33 patients received treatment A in wear period 4, and of these, 28/33 (85%) had a zero score at 8 h and 31/33 (94%) had a zero score at 12 h. For treatment B, 27/29 (93%) had zero scores at both 8 and 12 h. The adhesion scores for the end of each wear period (84 h) in Study 2 are shown in Table 8.
4. Discussion The results of Study 1 indicate that Estradot 100 mg/day produced comparable serum concentrations of estradiol to that from Menorest 100 mg/ day. Estradot 50 mg/day produced proportionally
Fig. 1. Mean serum estradiol levels for the three transdermal estradiol treatments, Estradot 5 cm2 (50 mg/day), Estradot 10 cm2 (100 mg/day) and Menorest 29 cm2 (100 mg/day), in Study 1 (n /11).
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Fig. 2. Mean serum estradiol levels for the two 50 mg/day transdermal estradiol treatments, Estradot 5 cm2 and Menorest 14.5 cm2, in Study 2 (n/30).
lower serum estradiol concentrations, as would be expected for half the dose. The estradiol Cmax values for the Estradot 100-mg/day and the Menorest 100-mg/day patches were not significantly different (1069/36 and 1029/39 pg/ml, respectively) and were approximately twice that of the Estradot 50-mg/day estradiol Cmax value of 559/14 pg/ml, demonstrating that lower systemic estradiol levels result from the smaller delivery system. The results of Study 2 indicate that steady-state levels were rapidly achieved, as shown by comparing the
mean 84-h levels after wear period 2 and wear period 4. This observation agrees with that from a recently published study [19] where the steady state had already been achieved during the first patch application. This observation suggests that both single- and multiple-dose study designs appear suitable for pharmacokinetic studies of estradiol transdermal patches. The authors of the recent study [19] discussed the possible existence of circadian estradiol plasma profiles in postmenopausal women after transdermal delivery with
Table 4 Mean pharmacokinetic parameters for estrone obtained after treatments with three different transdermal estradiol systems: Estradot 5 cm2 (50 mg/day) and 10 cm2 (100 mg/day) new generation patches and Menorest 29 cm2 (100 mg/day) existing patch, in Study 1 (n/11) Parameter
5 cm2 ETS (50 mg/day) Estradot mean (S.D.)
10 cm2 ETS (100 mg/day) Estradot mean (S.D.)
29 cm2 ETS (100 mg/day) Menorest mean (S.D.)
Cmax (pg/ml) Tmax (h) AUC0 84 (pg h/ ml) AUC0 108 (pg h/ ml)
75.6 (15.1) 58.9 (12. 5) 4661.8 (995.9)
97.0 (27.0) 45.8 (22.0) 6270.5 (1777.5)
98.3 (21.2) 48.0 (18.6) 6293.9 (1406.5)
5740.2 (1251.0)
7615.7 (2034.3)
7587.9 (1669.4)
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Table 5 Mean pharmacokinetic parameters for estrone obtained after treatments with two different transdermal estradiol systems: Estradot 5 cm2 (50 mg/day) new generation patch and Menorest 14.5 cm2 (50 mg/day) existing patch, in Study 2 (n/30) Parameter
5 cm2 ETS 14.5 cm2 ETS (50 mg/day) Estradot (50 mg/day) Menorest mean (S.D.) mean (S.D.)
Cmax (pg/ml) Tmax (h) Cmin (pg/ml) % Fluctuation AUC0 84b (pg h/ml) AUC0 96 (pg h/ ml)
41.7 (16.4) 42.4 (24.8) 31.3 (17.6) 45.0 (42.7) 2836 (1295)
41.3 (13.1) 35.4 (21.3) 30.0 (10.7) 41.8 (33.3) 2774 (871)
3185 (1474)
3108 (984)
matrix systems as a potentially complicating factor. The investigators also pointed out the absence of circadian estradiol profiles in postmenopausal women, and that the apparent circadian estradiol rhythms observed after transdermal application appear to mimic naturally occurring estradiol plasma profiles of premenopausal wo-
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men. The cause of the periodical estradiol plasma variations, whether occurring naturally or with transdermal patches, is currently a matter of conjecture. In our study, we did not detect any variations in plasma estradiol that would suggest the presence of circadian variations. The 50 mg/day new generation ETS Estradot produced comparable serum concentrations of estradiol to the 5-mg/day existing ETS Menorest and there was no significant difference (P /0.473) between estradiol Cmax values for the two ETS (579/30 and 539/20 pg/ml, respectively). These were comparable to the value obtained for Estradot 50 mg/day (559/14 pg/ml) in Study 1. The estradiol AUC0 84 and estradiol AUC0 108 values for the Estradot 100 mg/day and Menorest 100 mg/ day patches in Study 1 were almost identical, whilst the corresponding values for Estradot 50 mg/ day were proportionally lower (Table 3) and were consistent for half the dose delivered from this patch. In Study 2, the estradiol AUC0 84 and AUC0 96 values were very similar between Estradot 50 mg/day and Menorest 50 mg/day (Table 4).
Fig. 3. Mean serum estrone levels for the three transdermal estradiol treatments, Estradot 5 cm2 (50 mg/day), Estradot 10 cm2 (100 mg/ day) and Menorest 29 cm2 (100 mg/day), in Study 1 (n/11).
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Fig. 4. Mean serum estrone levels for the two 50 mg/day transdermal estradiol treatments, Estradot 5 cm2 and Menorest 14.5 cm2, in Study 2 (n/30).
Consistent with the rapid achievement of steady state, visual inspection of single-dose estradiol AUC0 84 data suggests reasonable agreement with the corresponding value for Estradot 50 mg/ day upon multiple-dose administration in Study 2. The two one-sided tests procedure, between Estradot 100 mg/day and the Menorest 100 mg/ Table 6 Two one-sided tests procedure confidence intervals: Estradot 10 cm2 (100 mg/day) ETS compared with the Menorest 29 cm2 (100 mg/day) ETS in Study 1 (n/11) Ratio of pharmacokinetic para- Lower limit meter (%)
Upper limit (%)
E2 E2 E2 E2 E1 E1 E1
120.09 106.89 103.23 109.22 106.78 106.66 107.26
Cmax AUC0 84 AUC0 108 AUC0 Cmax AUC0 84 AUC0 108
94.23 85.51 83.76 85.80 89.73 90.87 92.39
Confidence interval is derived from a logarithmic model, E2, estradiol, E1, estrone.
day in Study 1 and between Estradot 50 mg/day and the Menorest 50 mg/day in Study 2, demonstrated equivalence for estradiol and estrone pharmacokinetic parameters (Cmax and AUC). Results of the statistical analysis were no different for Study 2 when the outlier patient was included, except that the log-transformed Cmax value interval slightly exceeded the equivalence criterion. The calculated mean half-life values (t1/2) for estradiol ranged from 5.99/3.7 h for Menorest 100 mg/day to 7.79/4.1 h for Estradot 100 mg/day in Study 1, and from 6.99/2.9 h for Estradot 50 mg/day to 7.79/7.1 h for Estradot 50 mg/day in Study 2. These values are consistent with the mean half-life values obtained in previous transdermal estradiol studies [20,21]. The statistical analysis of pharmacokinetic parameters for estrone indicate that neither Estradot 100 mg/day and Menorest 100 mg/day (Study 1) nor Estradot 50 mg/day and Menorest 50 mg/day (Study 2) are significantly different with respect to metabolic conversion of estradiol to estrone. Postmenopausal estrone is derived primarily from
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197
Table 7 Two one-sided tests procedure confidence intervals: Estradot 5 cm2 (50 mg/day) ETS compared with Menorest 14.5 cm2 (50 mg/day) ETS in Study 2 (n /30) Ratio of pharmacokinetic
Lower limit (%)
Center (%)
Upper limit (%)
Equivalent
E2 E2 E2 E2 E1 E1 E1 E1
89.92 70.36 90.70 90.37 92.39 88.48 93.09 93.13
101.99 86.51 102.54 102.25 99.70 98.93 99.90 99.96
115.67 106.37 115.92 115.68 107.59 110.62 107.21 107.29
Yes Noa Yes Yes Yes Yes Yes Yes
Cmax Cmin AUC0 84 AUC0 96 Cmax Cmin AUC0 84 AUC0 96
Confidence interval is derived from a logarithmic model; E2, estradiol; E1, estrone. a The difference between the two treatments are trivial ( B/10%).
peripheral aromatization of androstenedione, and circulating concentrations are correlated with body weight [22,23]. About 15% of estradiol is converted to estrone per unit time and high doses of estradiol are known to increase serum estrone. Low physiological levels of estradiol were achieved with all patch systems used in these studies. Conversion of low levels of exogenous estradiol to estrone would be obscured by endogenous production of estrone from the internal steroid milieu of the normal postmenopausal woman. Hence, estrone does not appear to be a reliable measure of bioavailability for estradiol. Elimination rate constants, serum half-life and AUC0 could not be calculated for estrone in either of the studies, since there was no obvious elimination phase. The mean estrone serum profiles shown in Table 8 Incidence of patch adherence scores at 84 h (end of wear period), obtained after treatments with two different transdermal estradiol systems: Estradot 5 cm2 new generation (50 mg/ day) patch and Menorest 14.5 cm2 existing generation (50 mg/ day) patch, in Study 2 (n/32) Wear period
1 2 3 4
Estradot 5 cm2 ETS
Menorest 14.5 cm2 ETS
Scores
Scores
0
1
2
3
4
0
1
2
3
4
24 27 26 32
6 2 1 0
0 0 0 1
0 0 0 0
2 3 5 0
23 21 25 28
5 6 3 2
2 0 1 1
0 0 0 0
2 5 3 0
Figs. 3 and 4 indicate that estrone levels did not decline for more than 12 h after patch removal. The endogenous conversion of estradiol to estrone renders it impossible to calculate an elimination rate constant for estrone. The apparent dose values for the three transdermal systems investigated in Study 1 followed the predicted pattern, with mean values of 0.23, 0.46 and 0.532 mg/unit for the 5, 10 and 29 cm2 treatments, respectively. Similarly, the apparent dose values calculated for the two transdermal systems investigated in Study 2 were not statistically different (0.18 and 0.19 mg/unit for the 5 cm2 and 14.5 cm2 treatments). The adhesive properties of all the transdermal patches were good and there was little or no adhesive residue left on the skin of patients. A comparison of the data in Table 8 shows that although there is no significant difference between the two different ETS, Estradot had better adhesion than Menorest. This may be because Estradot is considerably smaller (65.5%) than Menorest. Of the Estradot application sites, 95.4% had no erythema, compared with 72.4% of the Menorest application sites. Skin irritation was low with all the different ETS.
5. Conclusions All ETS were safe and generally well tolerated in normal postmenopausal women with no significant skin irritation. Pharmacokinetic results in-
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dicate that upon the single-patch application, the Cmax and AUC of estradiol from Estradot 10 cm2 (100 mg/day) were bioequivalent to the reference Menorest 29 cm2 (100 mg/day) patch, whilst Estradot 5 cm2 (50 mg/day) delivered predictable and proportionally lower levels of estradiol. Similarly, the results from a multiple-dose study showed that the steady-state Cmax and AUC of estradiol from the Estradot 5 cm2 (50 mg/day) new generation estradiol transdermal patch were bioequivalent to the Menorest 14.5 cm2 (50 mg/day), the currently marketed estradiol transdermal patch. These pharmacokinetic results demonstrated consistent systemic delivery of estradiol from Estradot, a new generation ETS.
References [1] Ginsburg J, Hardiman P, Okolo S. Hormone replacement therapy in general practice. Br Med J 1991;302:1601 /2. [2] Birkhau¨ser MH, Haenggi W. Benefits of different routes of administration. Int J Fertil Menopausal Stud 1994;39(Suppl 1):11 /9. [3] Grodstein F, Stampfer MJ, Colditz GA, et al. Postmenopausal hormone therapy and mortality. New Engl J Med 1997;336:1769 /75. [4] Insogna K, Concato J, Henrich J. Boning up on estrogen: new options, new concerns. J Am Med Assoc 1996;276:1430 /2. [5] Kiel DP, Felson DT, Anderson JJ, Wilson PW, Moskowitz MA. Hip fracture and the use of estrogens in postmenopausal women. The Framingham Study. New Engl J Med 1987;317:1169 /74. [6] Schairer C, Adami HO, Hoover R, Persson I. Causespecific mortality in women receiving hormone replacement therapy. Epidemiology 1997;8:59 /65. [7] Archer DF, Furst K, Tipping D, Dain M-P, Vanderpol C. A randomized comparison of continuous combined transdermal delivery of estradiol-norethindrone acetate and estradiol alone for menopause. Obstet Gynecol 1999;94:498 /503. [8] Cooper C, Stakkestad JA, Radowicki S, et al. Matrix delivery transdermal 17b-estradiol for the prevention of bone loss in postmenopausal women. The International Study Group. Osteoporosis Int 1999;9:358 /66.
[9] Kuhl IL. Pharmacokinetics of oestrogens and progesterons. Maturitas 1990;12:171 /97. [10] Aedo AR, Landgren BM, Diczfalusy E. Pharmacokinetics and biotransformation of orally administerd oestrone sulphate and oestradiol valerate in postmenopausal women. Maturitas 1990;12:333 /43. [11] Balfour JA, McTavish D. Transdermal estradiol. A review of its pharmacological profile, and therapeutic potential in the prevention of postmenopausal osteoporosis. Drugs Aging 1992;2:487 /507. [12] Samsioe G. Hormone replacement therapy: expanding treatment options with transdermal delivery. Curr Ther Res Clin Exp 1999;60(3):161 /7. [13] Li C, Samsioe G, Wilaman K, et al. Effects of norethisterone acetate addition to estradiol in long term HRT. Maturitas 2000;36:139 /52. [14] Pornel B, Genazzani AR, Costes D, Dain M-P, Lelann L, Vanderpol C. Efficacy and tolerability of Menorest† 50 compared with Estraderm TTS† 50 in the treatment of postmenopausal symptoms: a randomized, multicenter, parallel group study. Maturitas 1995;22:207 /18. [15] Notelovitz M. Clinical experience with a 7-day estrogen patch: principles and practice. Gynecol Endocrinol 1998;12:248 /58. [16] Stevenson JC. Optimising delivery systems for HRT. Maturitas 1999;33(Suppl. 1):S31 /8. [17] Noonan PK, Gonzalez MA, Ruggirello D, et al. Relative bioavailability of a new transdermal nitroglycerin delivery system. J Pharm Sci 1986;75:688 /91. [18] Shumaker RC. PKCALC. Princeton, NJ: Wallace Laboratories, 1993 version. [19] Rohr UD, Seager-Lorenz K. 17 b-Estradiol matrixpatch removal and reapplication in postmenopausal women: theoretical predictions with an oscillating diffusion coefficient model. J Pharm Sci 2002;91:822 /44. [20] Report on Protocol 1004. A bioavailability study of three generations of transdermal estradiol in healthy postmenopausal women. September 1995. [21] Report on protocol 1012. A bioavailability study of two doses of Noven† second generation estradiol transdermal system compared with Noven† first generation estradiol transdermal system in healthy postmenopausal women, January 1997. [22] Longcope C, Baker S. Androgen and estrogen dynamics: relationships with age, weight and menopausal status. J Clin Endocrinol Metab 1993;76:601 /4. [23] Lipsett MB. Steroid hormones. In: Yen SSC, Jaffe RB, editors. Reproductive endocrinology, 2nd ed. Philadelphia: W.B. Saunders, 1986:140 /53.
Comparative bioequivalence studies with Estradot† and Menorest† transdermal systems M. Hossain a,1, E. Quebe-Fehling a, T. Sergejew a, G. Schmidt a, A. Skerjanec a,*, A. Cohen b,c,2, L. Krinsky d,3, Patricia Ibarra de Palacios a,1 b
a Novartis Pharma AG, Basel, Switzerland Peninsular Testing Corporation, 20215 NW 2nd Avenue, Suite 3, Miami, FL 33169, USA c Clinical Testing Corporation Research Unit, Opa Locka, FL 33056, USA d South Florida Bioavailability Clinic, Miami, FL, USA
Received 16 January 2002; received in revised form 24 March 2003; accepted 17 April 2003
Abstract Objectives: To compare the relative bioavailability of Estradot† , a small size, new generation estradiol transdermal system (ETS) to Menorest† , in healthy postmenopausal women. Methods: In two open-label, single center, randomized, crossover, bioequivalence studies, healthy postmenopausal women aged 40 /65 years received treatment with all the test regimens. In Study 1 (single-dose study), patients wore 5 cm2 (50 mg/day), 10 cm2 (100 mg/day) Estradot and 29 cm2 (100 mg/day) Menorest for 84 h. In Study 2 (multiple-dose study), patients wore a regimen of four consecutive treatments with a 5 cm2 (50 mg/day) new generation patch, Estradot and a 14.5 cm2 (50 mg/day) patch, Menorest. Blood samples were drawn at various time-points in both studies. Estradiol and estrone serum levels were determined by gas chromatography/mass spectrometry or radioimmunoassay methods. Skin irritation (erythema and edema), patch adherence and local skin reaction were assessed following patch removal. Results: In Study 1, baselineuncorrected Cmax for estradiol for Estradot 50 and 100 mg/day and Menorest 100 mg/day was 54.8, 106.2 and 101.6 pg/ ml, respectively, and Cmax for estrone was 75.6, 97.0 and 98.3 pg/ml, respectively. In Study 2, the baseline-uncorrected mean maximum serum concentration (Cmax) for estradiol for Estradot 50 mg/day and Menorest 50 mg/day patches was 56.7 and 52.7 pg/ml, respectively, and Cmax for estrone was 41.7 and 41.3 pg/ml, respectively. No significant skin irritation was observed in either study, but Estradot caused less skin irritation than Menorest. Conclusions: Estradot produced comparable serum concentrations of estradiol and estrone and caused less skin irritation than Menorest. # 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Transdermal; Estradiol; Matrix; Bioequivalence; HRT * Corresponding author. Present address: Novartis Pharmaceuticals, 1 Health Plaza, East Hanover, NJ 07936, USA. Tel.: /1-862778-6508; fax: /1-973-781-8865. E-mail addresses: [email protected] (A. Skerjanec), [email protected], [email protected] (A. Cohen), [email protected] (L. Krinsky), [email protected] (P. Ibarra de Palacios). 1 Tel.: /41-61-324-7540; fax: /41-61-324-5218. 2 Tel.: /1-305-621-4533; fax: /1-305-621-4534. 3 Tel.: /1-305-895-0304; fax: /1-305-895-8616. 0378-5122/03/$ - see front matter # 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/S0378-5122(03)00190-7
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1. Introduction Several studies have demonstrated that climacteric symptoms associated with the decline in endogenous estrogen in menopausal women can be alleviated by hormone replacement therapy (HRT) [1]. The beneficial effects of HRT are well established [2] and HRT is now an accepted treatment for the relief and prevention of menopausal symptoms such as vasomotor disturbances (hot flushes and sweating), urogenital atrophy and sleep disturbance. This treatment can also provide protection against other aetiologies [1,3 /7]. Oral treatment with natural or synthetic estradiol is a well-known and accepted method for treating estrogen deficiencies, but this method has its disadvantages. Orally administered estradiol is rapidly metabolized in the intestinal tract and liver to estrone and gluconuride conjugates which are excreted in bile or urine [8]. This degradation reduces the bioavailability of the administered estradiol [9,10] and leads to higher circulating levels of estrone than estradiol. Higher doses are, therefore, needed to achieve therapeutic serum concentrations of estradiol [8]. In contrast, the skin metabolizes estradiol only to a small extent and transdermal HRT systems offer distinct advantages over oral therapy, since estradiol is delivered directly into the bloodstream and the hepatic first-pass effect is avoided. Transdermal administration of estradiol produces therapeutic levels of estradiol with lower circulating levels of estrone and estrone conjugates and a more physiological estradiol: estrone ratio is achieved [11,12]. Smaller total doses are, therefore, needed with transdermal therapy than with oral therapy and, because estradiol has a relatively short halflife, transdermal administration of estradiol allows a rapid decline in blood levels after the system is removed. A study of the long-term effects of HRT has determined that the positive effects of transdermal HRT are more marked than those of oral therapy [13]. Transdermal therapy provides constant steady-state drug delivery, physiological estradiol levels and avoids the first-pass metabolism in the liver. Transdermal delivery systems for estradiol have been shown to be clinically effective in relieving menopausal symptoms and, further-
more, are non-invasive, easy to use and well accepted by patients. A new estradiol transdermal system (ETS), Estradot, has been developed which consists of estradiol contained in a multipolymeric adhesive platform using a patented DOT MatrixTM technology. Delivery optimized thermodynamics (DOT) is a new, highly efficient class of diffusion-based drug-in-adhesive technology that delivers more drug through less patch surface area without using irritating enhancers and with excellent adhesion. The drug is blended into microscopic pockets uniformly dispersed throughout the patch’s drug/ adhesive layer. This high-concentration gradient between the drug pocket and the skin optimizes the diffusion of drug from the patch, through the skin into the bloodstream. DOT patches are smaller, less irritating and more adherent than competitive reservoir-based and ordinary drug-inadhesive patches, which should offer better wear properties to the patient and result in better compliance. The surface area of the transdermal matrix patch determines the level of in vivo delivery of estradiol to the systemic circulation and ranges from 2.5 cm2, which delivers 25 mg/day, to 10 cm2 which delivers 100 mg/day, which would make this product the smallest of any of the currently approved products. Dosages can, therefore, be tailored to the needs of a specific patient. The smaller surface area of these new transdermal patches means that they are more likely to be acceptable, at the same time providing serum estradiol concentrations comparable with patches having a much larger surface area. Two independent studies were conducted where the primary objective was to determine the bioavailability of estradiol from the new multipolymeric matrix patches in healthy menopausal women. In the initial pilot clinical study (Study 1), Estradot patches with a surface area of 5 and 10 cm2, which were expected to release approximately 50 and 100 mg/day estradiol, respectively, were compared with Menorest, a currently marketed patch with a surface area of 29 cm2 and an expected delivery of 100 mg/day estradiol. In subsequent study (Study 2), the 5 cm2 multipolymeric matrix patch, Estradot (marketed as VivelleDotTM in the US) (50 mg/day estradiol
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release) was compared with a currently marketed transdermal estradiol patch having a surface area of 14.5 cm2 delivering 50 mg/day (marketed as Menorest in Europe or as VivelleTM in the US). In both studies, the secondary objective was the evaluation of the wear and irritation properties of these transdermal systems. The local irritation and sensitization of Menorest are well documented [8,14/16] and this was, therefore, considered to be an acceptable comparator.
2. Materials and methods 2.1. Patients Twelve patients were enrolled for Study 1 and 32 patients for Study 2. The populations for both studies were healthy, non-smoking, postmenopausal women (naturally or surgically induced) between the ages of 40 and 65 years and weighing between 108 and 187 pounds (lbs). Patients were in good health, as determined from a medical history, physical examination including pelvic examination, Pap smear, mammogram, electrocardiogram and routine laboratory safety tests. Postmenopausal status in patients was confirmed, based on a serum estradiol level 5/20 pg/ml and a serum follicle stimulating hormone (FSH) level ]/50 mIU/ml, measured from blood samples obtained during the screening examination. Supine blood pressure (BP), heart rate (HR) and respiratory rate (RR) were taken immediately prior to each treatment and then at 2 and 4 h after the patch application. Throughout the studies, patients were continuously observed and questioned for the occurrence of any adverse events. Written consent was obtained from all participants prior to entry into the study. 2.2. Method 2.2.1. Study 1 This was an open-label, single-center, singledose, randomized, three-treatment, three-period crossover bioavailability study. Each patient was randomly assigned to a crossover treatment sequence and received treatment with each of the
189
three test regimens. Each transdermal patch was applied to clean, dry, non-oily, non-irritated skin on the abdomen, below the waistline, for 84 h (3.5 days). After removal of each patch there was a 7day washout period between treatments. The three treatments were A: Estradot 5 cm2 new generation patch delivering approximately 50 mg/day, B: Estradot 10 cm2 new generation patch delivering approximately 100 mg/day and C, Menorest 29 cm2 existing patch delivering approximately 100 mg/ day. The latter was considered the reference patch for statistical analysis purposes. Blood samples (10 ml) for determination of serum concentration of estradiol and estrone, were taken 24 h prior to dosing (/24) and immediately prior to each treatment (0 h), then at 2, 4, 8, 12, 24, 36, 48, 60, 72, 84, 96 and 108 h after patch application. Blood collection, treatment and storage were as described in Study 1. Serum levels of estradiol and estrone were determined using a validated radioimmunoassay method. The analytical methods had a limit of quantification (LOQ) for estradiol of 6.46 pg/ml and an LOQ for estrone of 10.7 pg/ml in serum. The two pre-dose serum levels were used to calculate mean baseline estradiol and estrone concentrations. The estradiol content of worn patches after their removal from patients was assayed by HPLC and was used to calculate the apparent dose delivered by the three treatments. Adherence of the transdermal patches was evaluated at 2, 4, 8 and then every 12 h after application. After the removal of the patch, the application site was examined for any evidence of adhesive residue remaining on the skin site. The application site was examined for any evidence of local skin irritation (erythema and edema) approximately 1 min after patch removal and, again, 24 h after patch removal and the observations recorded. Patients completed a questionnaire in which they described their overall impression of the wear characteristics of the patch. Safety was monitored by means of pre- and post-treatment physical examinations. 2.2.2. Study 2 This was an open-label, single-center, multipledose, randomized, two-treatment, two-period,
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crossover, bioavailability study. Each patient was randomly assigned to a crossover treatment sequence and received treatment with each of the two test regimens. Each transdermal patch was applied to clean, dry, non-oily, non-irritated skin on the abdomen, below the waistline, for 84 h (3.5 days) for 4 consecutive wear periods, making a total of 14 days for each treatment. There was a 7day washout period between treatments. Treatment A was Estradot 5 cm2 new generation patch and treatment B was Menorest 14.5 cm2 existing patch, each delivering approximately 50 mg/day. The latter was considered the reference patch for statistical analysis purposes. Blood samples (7 ml) for determination of serum concentration of estradiol and estrone, were taken 36 h (/36) and 12 h (/12) prior to application of the first patch. Additional blood samples were drawn immediately prior to removal (84 h) at the end of the first, second and third wear periods. The third 84-h sample was also the 0-h sample for the fourth wear period. Following application of the fourth patch, blood samples were collected at 2, 4, 6, 8, 10, 12, 18, 24, 30, 36, 42, 48, 60, 72, 84, 88, 92 and 96 h. Venous blood was collected into red-top evacuated glass tubes which contained no preservatives or anticoagulants. The blood was allowed to clot at room temperature for at least 10 min, refrigerated for 2 h and the serum was then separated by centrifugation at 3000 rpm in a refrigerated centrifuge at 5 8C for 15 min. The supernatant was transferred into plastic specimen transfer vials and stored at /20 8C until time of assay for estradiol and estrone. Serum levels of estradiol and estrone were determined by a validated gas chromatography/mass spectrometry (GC/MS) method with an LOQ for estradiol of 2.5 pg/ml and an LOQ for estrone of 5.0 pg/ml in serum. The /36 and /12 h pre-dose serum levels were used to calculate mean baseline estradiol and estrone concentrations. The estradiol content of worn patches after removal from the patients was assayed by HPLC to determine the apparent clinical dose delivered by the two ETS. The apparent dose values were calculated from residual estradiol extracted from the transdermal systems after 84 h of wear by the patients in these studies, subtracted from a control value (the mean potency
of the lot used): Apparent dose /initial potency / residual potency. This parameter is known as the apparent dose because it is not possible to guarantee that all of the drug lost from a transdermal system is actually absorbed [17]. Adherence of the transdermal patches was evaluated at 2, 4, 8 and 84 h after the first, second and third wear periods. A replacement patch was provided to patients in the event of patch loss and the patients were instructed to record application time and dates for any replacement patches. During the fourth wear period, patch adherence was checked at 2, 4, 8, 12, then every 12 h until removal. Findings were recorded as an estimate of the percentage of the patch surface in contact with the skin, according to a 5-point scale of 0/4, where 0/patch adhered /90% (completely on); 1 / patch adhered 75 /90% (edges lifting off or center raised); 2 /50 /75% (half off); 3 /patch adhered B/50% (just hanging on); and 4 /patch not present on skin. Immediately following removal of the patch, the application site was examined for any evidence of adhesive residue remaining on the skin and graded on a 4-point scale of 0/3, where 0/none; 1/light; 2/medium; and 3 /heavy. Approximately 1 min and 1 and 12 h after patch removal, the application site was examined for evidence of local skin irritation. Topical irritation was graded according to a 6-point scale of 0 /5 where 0 /no erythema; 1 /‘ring’ erythema, ring limited to perimeter of the contact site; 2 /(mild) pink, uniform erythema with or without edema covering most of the contact site; 3/(moderate) pink-red erythema with or without edema uniform in the entire contact site; 4/(marked) bright-red erythema with or without edema, petechiae or papules; and 5/(severe) deep-red erythema with or without edema, vesiculation or weeping, severe erythema (beet-redness to slight eschar formation, injuries in depth). 2.2.3. Pharmacokinetic analysis Pharmacokinetic parameters were calculated for baseline-uncorrected estradiol and estrone, for each patient and each treatment, using ‘PKCALC’, software for non-compartmental pharmacokinetic data analysis [18]. In Study 1, the following pharmacokinetic parameters were calculated
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from the serum data. Cmax, Tmax, AUC0 84 /area under the concentration /time curve from 0 to 84 h (time during transdermal estradiol patch application) calculated using the linear trapezoidal rule (pg h/ml), AUC0 108 /area under the concentration /time curve from time 0 to the last serum value measured, Clast calculated using the linear trapezoidal rule, (pg h/ml), AUC0 / AUC calculated using the linear trapezoidal rule from 0 time to the time of the last measurable concentration and extrapolated to infinity using Clast/ke to calculate the residual area from Clast to infinity (pg h/ml). AUC0 , ke and t1/2 were calculated for estradiol only. In Study 2, the following pharmacokinetic parameters were calculated from the steady-state serum data; Cmax, maximum serum concentration (pg/ml), Tmax, time to maximum plasma concentration (h), Cmin, the steady-state trough serum concentration (84-h), % fluctuation /[100(Cmax / Cmin)/Cmin], AUCss, area under the serum concentration curve during a dosing interval at steady state. This is equivalent to AUC0 84, area under the concentration /time curve calculated from 0 to 84 h during the fourth wear period (time of ETS application). Values were calculated using the linear trapezoidal rule (pg h/ml). AUC0 96, area under the concentration /time curve from time 0 to the last serum value measured after last dose (fourth wear period), calculated using the linear trapezoidal rule from 0 to 96 h, (pg h/ml), ke, elimination rate constant, from loge, linear regression of points using the terminal linear portion of the logarithm transformed serum estradiol concentrations beginning with the 84-h sample collected at the time of patch removal, (per h). The parameter, ke, was calculated for estradiol only, t1/2, apparent terminal elimination half-life of drug in serum, (h). The t1/2 was calculated from the individual ke values using the relationship t1/2 / loge 2/ke. 2.2.4. Statistical analysis In both studies, an analysis of variance (ANOVA) of the pharmacokinetic parameters was calculated. The sequence effect was tested against patient within sequence. In Study 1, a Tukey multiple comparisons procedure was used to test
191
pairwise differences between treatments. The two one-sided tests procedure and a 20% equivalence criterion was used to evaluate the equivalence between the Estradot 10 cm2 and the reference Menorest 29 cm2 patches. In Study 2, Type III sums of squares were used throughout. Two one-sided tests and an 80 /125% equivalence criterion were performed for the logtransformed parameters (Cmax, Cmin, AUC0 84, AUC0 96) using the Estradot 5 cm2 as test and Menorest 14.5 cm2 patch as the reference formulation. To demonstrate that steady state levels were obtained during the multiple-dosing regimen, the 84-h values obtained after the second wear period were compared with the 84-h values after the fourth wear period. For both of these wear periods, the 84-h samples were collected at 20:00 h to minimize the potential confounding effect of circadian rhythms.
3. Results All patients (12 in Study 1 and 32 in Study 2) completed their respective study. In Study 1, analysis of serum estradiol pharmacokinetic parameters suggested that one patient who had a treatment ratio higher than those of the other 11 patients was an outlier in this study and data from this patient was, therefore, excluded from the analyzes. In Study 2, two patients were excluded from the pharmacokinetic data analysis due to errors in dosing */one patient lost her patch during treatment period 1, wear period 1 and inadvertently applied the release liner from the back-up patch, and one patient inadvertently received treatment with the Estradot 50 mg/day patch instead of the Menorest 50 mg/day patch during treatment period 1, wear period 4. These two patients were included in the safety analysis. Baseline demographics for patients in both studies are shown in Table 1. 3.1. Pharmacokinetic data The results of the pharmacokinetic analysis for estradiol are summarized in Tables 2 and 3 for Study 1 and Study 2, respectively, and mean
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192
Table 1 Baseline demographics for patients
Study 1 (n/11) Range (min and max) Study 2 (n/ 32)3 Range (min and max)
Age (year) mean (S.D.)
Weight (lb) mean (S.D.)
Height (in.) mean (S.D.)
55.8 (6.7) 40 /63 55.8 (5.1) 43 /65
146.0 (23) 111 /182 151.2 (20.1) 108 /187
63.1 (3.2) 58 /68 63.8 (2.2) 60 /68
estradiol serum concentration /time profiles for these studies are shown in Figs. 1 and 2, respectively. The pharmacokinetic analysis for estrone is summarized in Tables 4 and 5 for Study 1 and Study 2, respectively, and mean estrone serum concentration /time profiles are shown in Figs. 3 and 4, respectively. The mean apparent dose values calculated from residual estradiol extracted from the transdermal systems after 84 h of wear by the patients in these studies are included in Tables 2 and 3 for Study 1 and Study 2, respectively. Data are expressed as mean and standard deviation. The statistical analysis, shown as Two one-sided tests procedure confidence intervals for Study 1 and Study 2 are presented in Tables 6 and 7, respectively. Elimination rate constants and serum halflife values could not be determined for estrone in either study due to the lack of an observable elimination phase. The estradiol elimination rate
constant, ke, was calculated from the terminal linear portion of the logarithmic serum concentration versus time plot, beginning with samples collected at the time of patch removal (84 h) and is shown in Table 2 for the 5, 10 and 29 cm2 ETS in Study 1 and in Table 3 for the 5 and 14.5 cm2 ETS in Study 2.
3.1.1. Clinical observations Seven of the 12 patients (58%) enrolled in Study 1 and five of the 32 patients (16%) enrolled in Study 2 reported at least one adverse event during the treatment. All incidences except one were rated as mild in severity and were resolved during the study. A single episode of diarrhea was moderate in severity. The most frequently reported event was headache (five reports in Study 1; three in Study 2). Nausea, neck pain, leg pain, constipa-
Table 2 Mean pharmacokinetic parameters for estradiol obtained after treatments with three different transdermal estradiol systems: Estradot 5 cm2 (50 mg/day) and 10 cm2 (100 mg/day) new generation patches and Menorest 29 cm2 (100 mg/day) existing patch, in Study 1 (n/ 11) Parameter
5 cm2 ETS (50 mg/day) Estradot mean (S.D.)
10 cm2 ETS (100 mg/day) Estradot mean (S.D.)
29 cm2 ETS (100 mg/day) Menorest mean (S.D.)
Cmax (pg/ml) Tmax (h) AUC0 84 (pg h/ ml) AUC0 108 (pg h/ ml) AUC0 (pg h/ ml) ke (per h) t1/2 (h)
54.8 (13.9) 34.9 (19.5) 3569.4 (763.5)
106.2 (35.9) 29.5 (19.6) 6029.5 (2384.6)
101.6 (39.1) 27.3 (20.1) 6068.5 (1762.2)
3677.8 (1032.0)
6408.6 (2515.7)
6497.8 (1788.0)
3969.6 (860.2)
6971.8 (2190.2)
6590.1 (1787.8)
0.1274 (0.0787) 6.88 (2.92)
0.1249 (0.0823) 7.69 (4.14)
0.1863 (0.1453) 5.94 (3.68)
0.23 (0.06) 0.066 (0.02)
0.46 (0.20) 0.131 (0.06)
0.53 (0.11) 0.151 (0.03)
Apparent dose (mg/unit) (mg/day)
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Table 3 Mean pharmacokinetic parameters for estradiol obtained after treatments with two different transdermal estradiol systems: Estradot 5 cm2 (50 mg/day) new generation patch and Menorest 14.5 cm2 (50 mg/day) existing patch, in Study 2 (n/30) Parameter
5 cm2 ETS Estradot (50 mg/day) mean (S.D.)
14.5 cm2 ETS Menorest (50 mg/day) mean (S.D.)
Cmax (pg/ml) Tmax (h) Cmin (pg/ml) % Fluctuation AUC0 84 (pg h/ml) AUC0 96 (pg h/ml) ke (per h) t1/2 (h)
56.7 (30.7) 30.7 (15.6) 28.1 (19.5) 158.0 (190.8) 3088 (1721)
52.7 (20.0) 22.0 (13.5) 29.4 (12.3) 89.2 (59.4) 2886 (1147)
3268 (1865)
3051 (1191)
0.138 (0.079) 7.7 (7.1)
0.132 (0.056) 6.3 (2.7)
Apparent dose (mg/unit) 0.18 (0.05) (mg/day) 0.05 (0.01)
0.19 (0.09) 0.05 (0.02)
tion, diarrhea, dry cough, back pain and myalgia were also reported.
193
3.1.2. Transdermal system assessments All the transdermal systems adhered well to the volunteers throughout each of the 84-h application periods. In Study 2, all Estradot 5 cm2 patches scored 0, i.e. /90% (completely on) in the first 12 h of wear periods 1, 2 and 3. In the same time period, four Menorest 14.5 cm2 patches scored 1 (75 /90% on). The error in dosing of one patient meant that 33 patients received treatment A in wear period 4, and of these, 28/33 (85%) had a zero score at 8 h and 31/33 (94%) had a zero score at 12 h. For treatment B, 27/29 (93%) had zero scores at both 8 and 12 h. The adhesion scores for the end of each wear period (84 h) in Study 2 are shown in Table 8.
4. Discussion The results of Study 1 indicate that Estradot 100 mg/day produced comparable serum concentrations of estradiol to that from Menorest 100 mg/ day. Estradot 50 mg/day produced proportionally
Fig. 1. Mean serum estradiol levels for the three transdermal estradiol treatments, Estradot 5 cm2 (50 mg/day), Estradot 10 cm2 (100 mg/day) and Menorest 29 cm2 (100 mg/day), in Study 1 (n /11).
M. Hossain et al. / Maturitas 46 (2003) 187 /198
194
Fig. 2. Mean serum estradiol levels for the two 50 mg/day transdermal estradiol treatments, Estradot 5 cm2 and Menorest 14.5 cm2, in Study 2 (n/30).
lower serum estradiol concentrations, as would be expected for half the dose. The estradiol Cmax values for the Estradot 100-mg/day and the Menorest 100-mg/day patches were not significantly different (1069/36 and 1029/39 pg/ml, respectively) and were approximately twice that of the Estradot 50-mg/day estradiol Cmax value of 559/14 pg/ml, demonstrating that lower systemic estradiol levels result from the smaller delivery system. The results of Study 2 indicate that steady-state levels were rapidly achieved, as shown by comparing the
mean 84-h levels after wear period 2 and wear period 4. This observation agrees with that from a recently published study [19] where the steady state had already been achieved during the first patch application. This observation suggests that both single- and multiple-dose study designs appear suitable for pharmacokinetic studies of estradiol transdermal patches. The authors of the recent study [19] discussed the possible existence of circadian estradiol plasma profiles in postmenopausal women after transdermal delivery with
Table 4 Mean pharmacokinetic parameters for estrone obtained after treatments with three different transdermal estradiol systems: Estradot 5 cm2 (50 mg/day) and 10 cm2 (100 mg/day) new generation patches and Menorest 29 cm2 (100 mg/day) existing patch, in Study 1 (n/11) Parameter
5 cm2 ETS (50 mg/day) Estradot mean (S.D.)
10 cm2 ETS (100 mg/day) Estradot mean (S.D.)
29 cm2 ETS (100 mg/day) Menorest mean (S.D.)
Cmax (pg/ml) Tmax (h) AUC0 84 (pg h/ ml) AUC0 108 (pg h/ ml)
75.6 (15.1) 58.9 (12. 5) 4661.8 (995.9)
97.0 (27.0) 45.8 (22.0) 6270.5 (1777.5)
98.3 (21.2) 48.0 (18.6) 6293.9 (1406.5)
5740.2 (1251.0)
7615.7 (2034.3)
7587.9 (1669.4)
M. Hossain et al. / Maturitas 46 (2003) 187 /198
Table 5 Mean pharmacokinetic parameters for estrone obtained after treatments with two different transdermal estradiol systems: Estradot 5 cm2 (50 mg/day) new generation patch and Menorest 14.5 cm2 (50 mg/day) existing patch, in Study 2 (n/30) Parameter
5 cm2 ETS 14.5 cm2 ETS (50 mg/day) Estradot (50 mg/day) Menorest mean (S.D.) mean (S.D.)
Cmax (pg/ml) Tmax (h) Cmin (pg/ml) % Fluctuation AUC0 84b (pg h/ml) AUC0 96 (pg h/ ml)
41.7 (16.4) 42.4 (24.8) 31.3 (17.6) 45.0 (42.7) 2836 (1295)
41.3 (13.1) 35.4 (21.3) 30.0 (10.7) 41.8 (33.3) 2774 (871)
3185 (1474)
3108 (984)
matrix systems as a potentially complicating factor. The investigators also pointed out the absence of circadian estradiol profiles in postmenopausal women, and that the apparent circadian estradiol rhythms observed after transdermal application appear to mimic naturally occurring estradiol plasma profiles of premenopausal wo-
195
men. The cause of the periodical estradiol plasma variations, whether occurring naturally or with transdermal patches, is currently a matter of conjecture. In our study, we did not detect any variations in plasma estradiol that would suggest the presence of circadian variations. The 50 mg/day new generation ETS Estradot produced comparable serum concentrations of estradiol to the 5-mg/day existing ETS Menorest and there was no significant difference (P /0.473) between estradiol Cmax values for the two ETS (579/30 and 539/20 pg/ml, respectively). These were comparable to the value obtained for Estradot 50 mg/day (559/14 pg/ml) in Study 1. The estradiol AUC0 84 and estradiol AUC0 108 values for the Estradot 100 mg/day and Menorest 100 mg/ day patches in Study 1 were almost identical, whilst the corresponding values for Estradot 50 mg/ day were proportionally lower (Table 3) and were consistent for half the dose delivered from this patch. In Study 2, the estradiol AUC0 84 and AUC0 96 values were very similar between Estradot 50 mg/day and Menorest 50 mg/day (Table 4).
Fig. 3. Mean serum estrone levels for the three transdermal estradiol treatments, Estradot 5 cm2 (50 mg/day), Estradot 10 cm2 (100 mg/ day) and Menorest 29 cm2 (100 mg/day), in Study 1 (n/11).
M. Hossain et al. / Maturitas 46 (2003) 187 /198
196
Fig. 4. Mean serum estrone levels for the two 50 mg/day transdermal estradiol treatments, Estradot 5 cm2 and Menorest 14.5 cm2, in Study 2 (n/30).
Consistent with the rapid achievement of steady state, visual inspection of single-dose estradiol AUC0 84 data suggests reasonable agreement with the corresponding value for Estradot 50 mg/ day upon multiple-dose administration in Study 2. The two one-sided tests procedure, between Estradot 100 mg/day and the Menorest 100 mg/ Table 6 Two one-sided tests procedure confidence intervals: Estradot 10 cm2 (100 mg/day) ETS compared with the Menorest 29 cm2 (100 mg/day) ETS in Study 1 (n/11) Ratio of pharmacokinetic para- Lower limit meter (%)
Upper limit (%)
E2 E2 E2 E2 E1 E1 E1
120.09 106.89 103.23 109.22 106.78 106.66 107.26
Cmax AUC0 84 AUC0 108 AUC0 Cmax AUC0 84 AUC0 108
94.23 85.51 83.76 85.80 89.73 90.87 92.39
Confidence interval is derived from a logarithmic model, E2, estradiol, E1, estrone.
day in Study 1 and between Estradot 50 mg/day and the Menorest 50 mg/day in Study 2, demonstrated equivalence for estradiol and estrone pharmacokinetic parameters (Cmax and AUC). Results of the statistical analysis were no different for Study 2 when the outlier patient was included, except that the log-transformed Cmax value interval slightly exceeded the equivalence criterion. The calculated mean half-life values (t1/2) for estradiol ranged from 5.99/3.7 h for Menorest 100 mg/day to 7.79/4.1 h for Estradot 100 mg/day in Study 1, and from 6.99/2.9 h for Estradot 50 mg/day to 7.79/7.1 h for Estradot 50 mg/day in Study 2. These values are consistent with the mean half-life values obtained in previous transdermal estradiol studies [20,21]. The statistical analysis of pharmacokinetic parameters for estrone indicate that neither Estradot 100 mg/day and Menorest 100 mg/day (Study 1) nor Estradot 50 mg/day and Menorest 50 mg/day (Study 2) are significantly different with respect to metabolic conversion of estradiol to estrone. Postmenopausal estrone is derived primarily from
M. Hossain et al. / Maturitas 46 (2003) 187 /198
197
Table 7 Two one-sided tests procedure confidence intervals: Estradot 5 cm2 (50 mg/day) ETS compared with Menorest 14.5 cm2 (50 mg/day) ETS in Study 2 (n /30) Ratio of pharmacokinetic
Lower limit (%)
Center (%)
Upper limit (%)
Equivalent
E2 E2 E2 E2 E1 E1 E1 E1
89.92 70.36 90.70 90.37 92.39 88.48 93.09 93.13
101.99 86.51 102.54 102.25 99.70 98.93 99.90 99.96
115.67 106.37 115.92 115.68 107.59 110.62 107.21 107.29
Yes Noa Yes Yes Yes Yes Yes Yes
Cmax Cmin AUC0 84 AUC0 96 Cmax Cmin AUC0 84 AUC0 96
Confidence interval is derived from a logarithmic model; E2, estradiol; E1, estrone. a The difference between the two treatments are trivial ( B/10%).
peripheral aromatization of androstenedione, and circulating concentrations are correlated with body weight [22,23]. About 15% of estradiol is converted to estrone per unit time and high doses of estradiol are known to increase serum estrone. Low physiological levels of estradiol were achieved with all patch systems used in these studies. Conversion of low levels of exogenous estradiol to estrone would be obscured by endogenous production of estrone from the internal steroid milieu of the normal postmenopausal woman. Hence, estrone does not appear to be a reliable measure of bioavailability for estradiol. Elimination rate constants, serum half-life and AUC0 could not be calculated for estrone in either of the studies, since there was no obvious elimination phase. The mean estrone serum profiles shown in Table 8 Incidence of patch adherence scores at 84 h (end of wear period), obtained after treatments with two different transdermal estradiol systems: Estradot 5 cm2 new generation (50 mg/ day) patch and Menorest 14.5 cm2 existing generation (50 mg/ day) patch, in Study 2 (n/32) Wear period
1 2 3 4
Estradot 5 cm2 ETS
Menorest 14.5 cm2 ETS
Scores
Scores
0
1
2
3
4
0
1
2
3
4
24 27 26 32
6 2 1 0
0 0 0 1
0 0 0 0
2 3 5 0
23 21 25 28
5 6 3 2
2 0 1 1
0 0 0 0
2 5 3 0
Figs. 3 and 4 indicate that estrone levels did not decline for more than 12 h after patch removal. The endogenous conversion of estradiol to estrone renders it impossible to calculate an elimination rate constant for estrone. The apparent dose values for the three transdermal systems investigated in Study 1 followed the predicted pattern, with mean values of 0.23, 0.46 and 0.532 mg/unit for the 5, 10 and 29 cm2 treatments, respectively. Similarly, the apparent dose values calculated for the two transdermal systems investigated in Study 2 were not statistically different (0.18 and 0.19 mg/unit for the 5 cm2 and 14.5 cm2 treatments). The adhesive properties of all the transdermal patches were good and there was little or no adhesive residue left on the skin of patients. A comparison of the data in Table 8 shows that although there is no significant difference between the two different ETS, Estradot had better adhesion than Menorest. This may be because Estradot is considerably smaller (65.5%) than Menorest. Of the Estradot application sites, 95.4% had no erythema, compared with 72.4% of the Menorest application sites. Skin irritation was low with all the different ETS.
5. Conclusions All ETS were safe and generally well tolerated in normal postmenopausal women with no significant skin irritation. Pharmacokinetic results in-
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M. Hossain et al. / Maturitas 46 (2003) 187 /198
dicate that upon the single-patch application, the Cmax and AUC of estradiol from Estradot 10 cm2 (100 mg/day) were bioequivalent to the reference Menorest 29 cm2 (100 mg/day) patch, whilst Estradot 5 cm2 (50 mg/day) delivered predictable and proportionally lower levels of estradiol. Similarly, the results from a multiple-dose study showed that the steady-state Cmax and AUC of estradiol from the Estradot 5 cm2 (50 mg/day) new generation estradiol transdermal patch were bioequivalent to the Menorest 14.5 cm2 (50 mg/day), the currently marketed estradiol transdermal patch. These pharmacokinetic results demonstrated consistent systemic delivery of estradiol from Estradot, a new generation ETS.
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