Absorption and metabolism of oral progesterone when administered twice daily*

FERTILITY AND STERILITY Copyright Q 1986 The American Fertility Society

Vol. 46, No.3, September 1986 Printed in U.S A.

Absorption and metabolism of oral progesterone when administered twice daily*

Malcolm L. Padwick, M.B. t Julie Endacott, S.R.N.:t: Christine Matson, Ph.D.§ Malcolm I. Whitehead, M.R.C.O.G.II Academic Department of Obstetrics and Gynaecology, King's College School of Medicine and Dentistry, London, United Kingdom

The absorption, metabolism, and clearance of progesterone (P) from the peripheral circulation were investigated in five postmenopausal women after oral administration of 100 mg at 9:00 A.M. and 200 mg at 9:00 P.M. for 5 consecutive days. Mean peak plasma concentrations of P were observed 2 hours after ingestion of both the 100 and 200 mg doses and were 22.7 and 47.7 nmolll, respectively. Of the three metabolites studied, the plasma concentrations of pregnanediol-3ot-glucuronide were most raised by treatment; those of 17-hydroxyprogesterone were least raised. Increases in the plasma levels of 20ot-dihydroprogesterone were more sustained than those of P, and the plasma concentrations remained elevated at approximately 20 nmolll for at least 12 hours after P administration. We conclude that administration of oral P 100 mg in the morning and 200 mg at night increases the circulating concentrations of P and the biologically active metabolite 20ot-dihydroprogesterone, and that the duration of these increases is sufficient to evoke progestational responses in responsive endorgans. Fertil Steril46:402, 1986

Although synthetic progestogens have been used for many years, the importance of their metabolic effects has been appreciated only comparatively recently. The C-19 nor-steroid derivatives, such as norethindrone and norgestrel, have been investigated most comprehensively. When added

Received December 3, 1985; revised and accepted May 14, 1986. *Supported by a grant from Laboratoires Besins Iscovesco, Paris, France. tResearch Registrar. tClinic Sister. §Research Assistant. IIReprint requests: Malcolm 1. Whitehead, M.R.C.O.G., Senior Lecturer/Consultant Gynecologist, Academic Department of Obstetrics and Gynaecology, King's College School of Medicine and Dentistry, Denmark Hill, London SE5 8RX, United Kingdom. 402

Padwick et al. Pharmacokinetics of oral P

to estrogens in either oral contraceptives (OCs) or for postmenopausal therapy, these androgenic progestogens have been shown to affect lipid metabolism adversely by suppressing the high-densitylipoprotein (HDL) cholesterol fraction. I, 2 During OC therapy, this suppression has been linked to an increase in risk of arterial disease. 3 Two major alterations to OCs and postmenopausal therapy have been introduced in an attempt to minimize this potential hazard. The first is dosage reduction: the new generation of "triphasic" OCs which contain less progestogen each cycle cause fewer metabolic disturbances than their predecessors,4 and the addition of a low dose of norethindrone, 1 mg daily, to postmenopausal estrogens minimizes adverse lipid changes. 5 The second strategy has been to use a progestogen from a different class. Medroxyprogesterone Fertility and Sterility

acetate (MPA) is a 17 -hydroxyprogesterone (17-0HP) derivative that is considered less androgenic than the C-19 nor-steroid derivatives. When added to postmenopausal estrogens at a dose of 10 mg daily, MPA has been reported as causing no adverse changes in lipid metaboli~m.6-8 However, in a more recent study, Ottoson et al. 9 used a larger number of patients and observed that 10 mg MPA daily significantly lowered HDL cholesterol and, in particular, the HDL2 subfraction. The latter is currently believed to be especially important in determining the risk for arteriosclerotic disease. 1o Interestingly, Ottoson and co-workers9 also studied oral micronized progesterone (P), 100 mg twice daily, and reported no change in lipid status over the 3-month study period. We have previously reported that micronized P is absorbed after oral administration and that plasma levels within the secretory phase range are maintained for approximately 4 hours with 100 mgY We doubted whether this time span would be sufficient to effect a full end-organ response and subsequently observed incomplete progestational action on endometrial histology and biochemistry with 100 mg daily.12 However, when given in divided doses, 200 to 300 mg P daily achieved good progestational activity within the endometrium. 12 Given the absence of lipid effects9 and good endometrial responses 12 with oral P, we designed the present study to assess the rate of absorption of oral P when given in divided doses and to determine the concentration appearing in the peripheral circulation. We studied the hormone's metabolism by determining its conversion to pregnanediol-3a-glucuronide (PGD), 20a-dihydroprogesterone (20-DHP) and 17-0HP. MATERIALS AND METHODS

Five asymptomatic postmenopausal women volunteered to participate in the study. All were parous, had intact ovaries, and had experienced a natural menopause between 2 and 10 years previously. Their ages ranged from 52 to 59 years and their weights from 59.5 to 70 kg. None of the patients had received hormonal medication in the previous 5 years. The study lasted 11 days. To obtain baseline values we performed venipuncture between 9:00 A.M. and 10:00 A.M. on days 1 and 2. For the next 5 consecutive days (days 3 to 7) one P capsule Vol. 46, No.3, September 1986

(Utrogestan, Laboratoires Besins Iscovesco, Paris, France) containing 100 mg pure steroid was given orally at 9:00 A.M., and another two capsules (200 mg) were given at 9:00 P.M. On days 7 and 8, serial blood samples were collected via an indwelling catheter from all patients. Sampling commenced on day 7 immediately before ingestion of the 100 mg P capsule at 9:00 A.M. Samples were withdrawn every 30 minutes until 10:00 A.M., every hour until 1:00 P.M., and then every 2 hours until 5:00 P.M. After administration of the 200 mg dose at 9:00 P.M., blood samples were collected at the same intervals: 30 minutes until 10:00 P.M., every hour until 1:00 A.M. on day 8, and then every 2 hours until 5:00 A.M. on day 8. Additional blood samples were taken at 9:00 A.M. on days 8, 9, 10, and 11, that is, 12, 36, 60, and 84 hours after the last two capsules were administered. Each 20-ml blood sample was collected into lithium heparin tubes and centrifuged immediately, and the plasma was stored at - 20°C until assayed. After the withdrawal of each sample, a heparin flush was administered to keep the cannula patent. The first 5 ml of blood withdrawn at every sampling was discarded for prevention of contamination by the heparin. All concentrations of steroid hormones were measured by radioimmunoassay. The method for the measurement of P was that described by Youssefnejadian et al.,13 except that we used a more specific antiserum to P, 11a-succinyl bovine thyroglobulin, which reduced cross-reaction with 5a-dihydroprogesterone to < 15%. We measured 20-DHP and 17-0HP concentrations by the method of Florensa and Sommerville 14 and Youssefnejadian et al.,15 respectively. We measured the concentration of PGD in a 50-1.1.1 plasma aliquot by adapting the method for estimating the concentration in urine. 16 STATISTICAL ANALYSIS

For each steroid, the distribution of values was skewed and the data were log-transformed before analysis. The mean values for days 1 and 2 were compared with the morning and evening mean peak values on day 7 and the 9:00 A.M. values on days 8, 9, 10, and 11 with the use of Student's paired t-test. The peak levels of P and the times that these were attained following morning and evening administration were determined by inspection. Intersubject differences and dose effects Padwick et aI. Pharmacokinetics of oral P

403

curred slightly later, ranging from 2 to 8 hours (mean, 3.6 hours ± 1.17 SEM) after administration of the higher dose. Similar patterns were observed for PGD, 20-DHP, and 17-0HP (Table 2). The mean values for the four hormones were calculated before treatment; during the profiles performed on days 7 and 8, and then 12, 36, 60, and 84 hours (days 8 to 11) after administration of the last P dose. These results are shown in Figure 2. A close temporal relationship was observed after administration of 100 mg P at 9:00 A.M. on day 7. Peak mean values for P, 20-DHP, and 17OHP occurred simultaneously 2 hours after capsule ingestion; peak mean values for PGD were observed a further 1 hour later. After administration of200 mg P at 9:00 P.M. on day 7, peak mean values for P and its three metabolites occurred simultaneously 2 hours later. After both morning and evening P doses on day 7, plasma P concentrations fell rapidly, and the mean values were < 10 nmolll within 12 hours of administration of either dose. The concentrations of 20-DHP were

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in log peak values and in times to peak on day 7, respectively, were investigated by analysis of variance. Confidence intervals were obtained for the ratio of evening/morning plasma levels. The standard deviation (SD) of individual log peak values was estimated as the square root of the sum of the components of variance between and within subjects.

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RESULTS Figure 1 shows the concentration of P in all samples from the five patients. All pretrea:tment concentrations (day 1 and day 2) were within the postmenopausal range for our laboratory. Wide interpatient differences in absorption of oral P are shown by the variation in the time taken to achieve maximal plasma concentrations after administration of 100 mg P at 9:00 A.M. and 200 mg P at 9:00 P.M. on day 7. Thus, the morning peak ranged from 1 to 4 hours after P administration (mean, 2.4 hours ± 0.51 standard error of the mean [SEM]), and the evening peak values oc404

Pad wick et aI. Pharmacokinetics of oral P

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Figure 2 Mean concentrations of plasma P and its three major metabolites before and after oral administration of P. Fertility and Sterility

Table 1. Mean Concentrations of Various Steroids in Peripheral Plasma of the Five Postmenopausal Women Before and After Oral Administration of P" Mean value from Morning mean day 1 and day 2 peak values

After last capsules administered (hrs)

Evening mean peak values

12

36

60

84

± SEM

P (nmol/I) 20.-DHP (nmolll) 17 -OHP (nmolll) PGD (nmolll)

22.7 b (4.9) 25.7 b (4.3) 7.48 b (0..69) 2540. b (361)

1.43 (0..27) 2.0.8 (0..63) 1.47 (0..27) 48.5 (1.5)

47.7 b (5.9) 32.6 b (5.3) 11.2b (1.1) 3643 b (266)

8.17 b (1.19 19.5 b (2.8) 4.22b (0..49 1247 b (370.)

4.33 d (0..80.) 13.2 b (3.0.) 3.51c (0..37) 764 b (186)

3.34d (0..64) 8.82 b (2.15) 2.15 d (0..22) 378c (10.7)

2.44d (0..58) 7.52c (2.47) 1.86d (0..23) 365c (92)

aStatistical comparisons on log data by Student's paired t-test; significance of values as compared with pretreatment (days 1 and 2) .

. bp < 0..0.1. cp < 0..0.5. dp < 0..1.

pretreatment range within 60 hours of the final 200-mg P dosage. _ The data on which the analysis of variance was performed are shown in Table 2: the peak plasma levels and time to peak for each of the four hormones in the five women are presented. Significant intersubject differences in peak levels were observed for 20-DHP (P < 0.05), for P at the 10% level, but not for PGD and 17-0HP (P > 0.1 for both). No significant differences were observed between subjects from the time of morning or evening administration of P to attainment of the peak level for any hormone. Significant effects of dose were present for all four hormones: this was greatest for P (P < 0.01), significant for 17 -OHP (P < 0.05), and weakest for PGD and 20-DHP lP < 0.1). The evening/morning dose ratio (and 95% confidence intervals) of peak plasma levels for the four hormones is shown in Table 3. The dose-response was strongest for P, less marked for PGD and

sustained longer than those of the parent compound and produced the most constant plasma profiles: the mean values were approximately 20 nmolll 12 hours after administration of both morning and evening doses. Concentrations of PGD exceeded those of 20-DHP, and 17-0HP levels were least raised. For each hormone, the mean peak values obtained on days 7 and 8 and the values observed 12, 36, 60, and 84 hours after the last P capsules were taken were compared with the values before treatment (Table 1). Concentrations of P were significantly raised when maximal (P < 0.01) and for at least 12 hours after last capsule administration (P < 0.01). Concentrations of 20-DHP and PGD were significantly raised when maximal (P < 0.01) and for at least 84 hours after the last capsules were taken (P < 0;05). Concentrations of 17-OHP were significantly raised when maximal (P < 0.01) and for at least 36 hours (P < 0.05) after the end of treatment; they fell to within the

Table 2. Plasma Peak Levels and Time to Peak for P and Its Major Metabolites After Administration of 100 mg Oral Pat 9:00 A.M. and 200 mg at 9:00 P.M. Subject

P Peak

POD Time to peak

Peak

Time to peak

Peak

hr.

hrs

17-OHP Time to peak

Peak

2O-DHP Time to peak

hr.

hr.

1 Morning Evening

38.92 64.33

3 2

3724 3379

3 2

7.55 13.84

2 2

41.56 50..0.4

3 6

Morning Evening

28.66 47.71

2 2

1951 360.3

1 2

9.31 12.87

2 2

16.83 26.0.1

1 2

Morning Evening

14.52 27.20.

1 '8

2798 30.52

4 8

7.43 7.67

4 8

19.77 18.0.0.

1 8

Morning Evening

17.26 49.43

2 4

2573 4636

1 4

8.0.4 11.18

3 3

26.20. 33.10.

0..5 6

Morning Evening

13.89 50..0.6

4 2

1653 3544

8 2

5.0.8 10..33

4 2

24.21 35.64

1 2

2 3 4 5

Vol. 46, No.3, September 1986

Pad wick et aI. Pharmacokinetics of oral P

405

Table 3. Evening/Morning Ratio for the Geometric Means of the Peak Levels of P and Its Major Metabolites After Oral Administration of 100 mg Pat 9:00 A.M. and 200 mg at 9:00 p.M.a

Evening/morning ratio 95% confidence intervals SD (log data)

P

PGD

17-0HP

2O-DHP

2.21

1.48

1.49

1.26

1.11,4.43 0.93, 2.35 1.07, 2.08 0.97, 1.63 0.39

0.26

0.23

0.36

aNinety-five percent intervals are shown. For explanation of SD (using log datal see "Statistical Analysis" section of text.

17-0HP, and weakest for 20-DHP_ The SD of individuallog peak values (Table 3) was considerable and was 50% larger for P and 20-DHP than for PGD and 17-0HP.

DISCUSSION

This study has confirmed our previous report, 11 and that of others, 17 that oral administration of P is associated with variations in the rate of absorption and with rapid metabolism and clearance from the peripheral circulation. In this study, we observed maximal plasma levels 1 to 4 hours after administration of 100 mg and 2 to 8 hours after ingestion of200 mg P (Fig. 1). Peak mean concentrations of the parent steroid and its three major metabolites occurred within 2 t03 hours of administration of the lower dose and simultaneously after ingestion of 200 mg P (Fig. 2). Although plasma P levels remained elevated above baseline for at least 84 hours after administration of the last dose, we doubt whether plasma values of 2.4 to 4.3 nmolll (Table 1) exert any significant biologic effect. Indeed, we would regard. plasma values of < 15 nmolll as indicating poor luteal function during the ovulatory cycle: plasma concentrations above this value were maintained for only 3 hours after administration of the 100 mg dose; and for 7 hours after 200 mg oral P (Fig. 2). During the 12 hours after administration of the 100- and 200-mg doses, the percentages of P observations for the five patients > 15 nmolll were 31% and 53%, respectively. In the previous studies, 11, 17 100 mg P was administered orally only once daily. Because of the rapid absorption and metabolism, we wondered whether increasing the dose would result in higher plasma levels of the parent hormone and its metabolites sustained for longer periods: the 406

Padwick et al. Pharmacokinetics of oral P

present results leave little doubt that this is so. The P values obtained after administration of200 mg P were approximately twice those observed after ingestion of the 100-mg dose: as compared with the morning dose, the values observed after evening administration were approximately 50% higher for PGD and 17 -OHP and 25% higher for 20-DHP (Tables 1 to 3). In biologic terms, the sustained increased in the plasma concentration of 20-DHP (Fig. 2, Table 1) may be important. 20-DHP is active in its own rightl 8 and is formed from P not only within the liver but also in target tissue such as the endometrium. 19 The plasma profile of 20-DHP was more constant than that ofP, and the concentrations 12 hours after P administration approximated 20 nmolll (Fig. 2). This probably reflects slower elimination. 2o The greatest increase in the concentrations of the major metabolites occurred with PGD: concentrations of 17 -OHP were least elevated and had returned to within the pretreatment range within 60 hours of discontinuing therapy (Fig. 2, Table 1). It was argued previously that increases in the plasma levels of 17 -OHP after P administration must be interpreted with cautionY Because of its partial adrenal origin, 17-0HP shows a diurnal variation with maximal values between 6:00 A_M. and 8:00 A.M.21 Thus, endogenous 17-OHP levels would be expected to decline during the late morning. In previous studies/I, 17 sampling occurred most frequently during the morning. In this study, we took blood samples overnight and observed a fourfold rise in 17-0HP levels during the 2 hours following administration of 200 mg P at 9:00 P.M., when plasma cortisol levels are known to be relatively constant and low. Our interpretation of this and our previous pharmacokinetic study is that once-daily administration of oral P, even at doses up to 200 mg, fails to achieve for sustained periods those plasma concentrations necessary to reproduce in full the end-organ responses typically observed during the secretory-phase of the ovulatory cycle. We suspect that oral P needs to be administered at least every 12 hours, or perhaps even every 8 hours, if the effects of endogenous P are to be mimicked completely. Indeed, we have previously reported that oral P, 200 mg daily, induces less complete secretory transformation within the estrogenized postmenopausal endometrium than 300 mg daily, given as 200 mg at night and 100 Fertility and Sterility

mg in the momingY We stress that the importance of these subtle endometrial differences, in terms of suppression of neoplastic change, remains to be elucidated. It is also clear from this study that marked interpatient variation in absorption and metabolism of P occurs. Significant between subject differences in peak levels were observed for 20-DHP CP < 0.05); for P, these differences achieved significance at only the 10% level. It is not known whether these differences reflect intrinsic variation in absorption and/or metabolism or whether they result from differences in eating habits and times at which meals are taken. We did not standardize food intake and the timing of meals. Clinically, we believe that oral P can be considered as a realistic alternative to synthetic progestogens for addition to postmenopausal estrogen therapy. The lack of adverse effects upon HDL2 cholesterol levels when given at dosages of 200 mg daily9 and 300 mg daily22 is particularly attractive in this context. Oral P may also have a role in the management of other progestogen-responsive conditions, such as anovulatory dysfunctional uterine bleeding. The major potential disadvantage of oral P is the further conversion to deoxycorticosterone,17 which may promote fluid retention, but we have no doubt that further studies on the therapeutic efficacy and possible side effects of oral P are warranted. Acknowledgments. The help of Marie-Aline Limouzin-Lamothe, M.D., was much appreciated. We thank Mrs. Helen Kenna, Miss Frances Stewart, and Miss Julie Bennett for all their assistance in the preparation of the manuscript. The help of Patrick Royston, M.I.S., M.Sc., with the statistical analyses is gratefully acknowledged.

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2.

3. 4.

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lipoprotein cholesterol in women using oral contraceptives, estrogens and progestins. N Engl J Med 229:17, 1978 Hirvonen E, Malkonen M; Manninen V: Effects of different progestogens on lipoproteins during postmenopausal replacement therapy. N Engl J Med 304:560, 1981 Kay CR: The happiness pill. J R ColI Gen Pract 30:8, 1980 Larsson-Cohn U, FahraeusL, Wallentin L, Zador G: Lipoprotein changes may be minimized by proper composition of a combined oral contraceptive. Fertil Steril 35:172, 1981 Christiansen C, Christensen MS, Grande P, Transbol I: Low-risk lipoprotein pattern in postmenopausal women on sequential oestrogen/progestogen treatment. Maturitas 5:193, 1984

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6. Notelovitz M, Gudat JC, Ware MD, Dougherty MC: Oestrogen-progestin therapy and the lipid balance of postmenopausal women. Maturitas 4:301, 1982 7. Silferstolpe G, Gustafsson A, Samsioe G, Svanborg A: Lipid metabolic studies in oophorectomised women: effects on serum lipids and .lipoproteins of three synthetic progestogens. Maturitas 4:103,1982 8. Mattsson L, Cullberg G, Samsioe G: Influence of esterified estrogens and medroxyprogesterone on lipid metabolism and sex steroids: study in oophorectomized women. Horm Metab Res 14:6(}2, 1982 9. Ottoson UB, Johansson BG, von Schoultz B: Subfractions· of high-density lipoprotein cholesterol during estrogen replacement. therapy: comparison between progestogens and natural progesterone. Am J Obstet GynecoI151:746, 1985 10. Miller NE, Hammett F, Saltissi S, Rao S, van Zeller H, Coltart J, Lewis B: Relation of angiographically defined coronary artery disease to plasma lipoprotein subfrac-· tions and apolipoproteins. BrMed J 282:1741,1982 11. Whitehead MI, Townsend PT, Gill DK, Collins WP, Campbell S: Absorption and metabolism of oral progesterone. Br Med J 280:825, 1980 12. Lane G, Siddle NC, Ryder TA, Pryse-DaviesJ, KingRJB, Whitehead MI: Dose-dependent effects of oral progesterone on the oestrogenised postmenopausal endometrium. Br Med J 287:1241, 1983 13. Youssefnejadian E, Florensa E, Collins WP, Sommerville IF: Radioimmunoassay of plasma progesterone. J Steroid Biochem 3:893, 1972 14. Florensa E, Sommerville IF: Radioimmunoassay of plasma 20a-dihydroprogesterone. Steroids 22:451, 1973 15. Youssefnejadian E, Florensa E, Collins WP, Sommerville IF: Radioimmunoassay of 17 -hydroxyprogesterone. Steroids 20:773, 1972 16. Collins ·WP, Collins PO, Kilpatrick MJ, Manning PA, Pike J, Tyler JP: The measurement of urinary oestrone3-glucuronide, LH and pregnanediol-3a-glucuronide as indices of ovarian function. Acta Endocrinol (Copenh) 90:336, 1979 17. Ottoson UB, Carlstrom K, Jamber JE, von Schoultz B: Serum levels of progesterone and some of its metabolites including deoxycorticosterone after oral and parenteral administration. Br J Obstet Gynaecol 91:1111, 1984 18. Zander J, Forbes TR, Von Munstermann AM, Neher R: .M-3 keto-pregnene-20a-ol and A4-3 ketopregnene-20~-ol, two naturally occurring metabolites of progesterone: isolation, identification, biologic activity and concentration in human tissues. J Clin Endocrinol Metab (Suppl 4) 18:337, 1958 19. Collins WP, Mansfield MD, Bridges CE, Sommerville IF: Studies on steroid metabolism in human endometrial tissue. Biochem J 113:399, 1969 20. Aedo AR, Pedersen PH, Pedersen SZ, Diczfalusy E: Ovarian steroid secretion in normally menstruating women. II. The contribution of the corpus luteum. Acta Endocrinol (Copenh) 95:222, 1981 21. Landgren BM, Campa S, Cekan SZ, Diczfalusy E: Studies on the pattern of circulating steroids in the normal menstrual cycle 5: changes around the onset of menstruation. Acta Endocrinol (Copenh) 86:608, 1971 22. Fahraeus .L, Larsson-Cohn U, Wallentin L: L-norgestrel and progesterone have different influences on plasma lipoproteins. Eur J Clin Invest 30:447, 1983 Padwick et aL Pharmacokinetics of oral P

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