Plant sterols added to combination statin and colesevelam hydrochloride therapy failed to lower low-density lipoprotein cholesterol concentrations

Journal of Clinical Lipidology (2007) 1, 626 – 633

Plant sterols added to combination statin and colesevelam hydrochloride therapy failed to lower lowdensity lipoprotein cholesterol concentrations Sunny A. Linnebur, PharmD, FASCP, BCPS, CGP,* Warren H. Capell, MD, Joseph J. Saseen, PharmD, FCCP, BCPS, CLS, Pamela Wolfe, MS, Robert H. Eckel, MD, FAHA, FACC Departments of Clinical Pharmacy (Drs. Linnebur and Saseen), Medicine (Drs. Capell and Eckel), and Preventive Medicine and Biometrics (Dr. Wolfe), University of Colorado-Denver, 12631 East 17th Ave, PO Box 6511, Aurora, CO 80045, USA KEYWORDS: Absorption; Colesevelam; Phytosterols; Hyperlipidemia; HydroxymethylglutarylCoA reductase inhibitors

BACKGROUND: The purpose of this study was to evaluate the effects on LDL-cholesterol (LDL-C) from addition of plant sterol treatment to patients with dyslipidemia already taking a statin and colesevelam hydrochloride (HCl). Current cholesterol treatment guidelines recommend use of plant stanols/sterols to help reach LDL-C goals in patients taking other lipid-lowering therapies. Previous data demonstrate LDL-C lowering by adding stanols/sterols to statins. However, data are conflicting regarding the benefit from combination stanols/sterols with bile acid sequestrants. METHODS: Fifty-five subjects on a stable dose of statin completed a 10-week, double-blind, randomized study of colesevelam HCl 3.75 g/day alone for 4 weeks, then 6 weeks of additional 2 g/day plant sterol-fortified orange juice (S-OJ) or placebo orange juice (P-OJ). Serum total cholesterol (TC), LDL-C, HDL-cholesterol (HDL-C), triglycerides (TG), apolipoprotein B (ApoB), and high-sensitivity C-reactive protein (hs-CRP) were measured at baseline, 4 weeks, and 10 weeks. RESULTS: Baseline LDL-C measurements (mean ⫾ SD) were similar between S-OJ and P-OJ groups (122 ⫾ 20 vs 126 ⫾ 24 mg/dL, respectively). Four weeks of colesevelam HCl in combination with a statin significantly reduced TC, LDL-C, and ApoB (9.6%, P ⬍ 0.001; 21.9%, P ⬍ 0.001; and 8.5%, P ⫽ 0.001, respectively), and significantly increased HDL-C (6.2%, P ⫽ 0.002) and TG (18.8%, P ⫽ 0.002). However, compared to P-OJ, 10 weeks of S-OJ produced no effect on any outcome parameter beyond that of colesevelam HCl. CONCLUSION: Plant S-OJ appears to be ineffective at further reducing LDL-C when added to statin and colesevelam HCl combination therapy in patients with dyslipidemia. © 2007 National Lipid Association. All rights reserved.

Data from this study was presented as a poster at the American College of Cardiology 56th Annual Scientific Session, New Orleans, LA, on March 26, 2007 and as an encore presentation at the American College of Clinical Pharmacy 2007 Spring Practice and Research Forum, Memphis, TN, on April 23, 2007. * Corresponding author. E-mail address: [email protected]

Coronary heart disease (CHD) is the primary cause of morbidity and mortality in the United States.1 Elevated serum low-density lipoprotein cholesterol (LDL-C) is a major risk factor for CHD, and clinical studies have shown that reducing LDL-C in patients with or without CHD reduces coronary events and death.2-7 The National Cholesterol Education Program (NCEP) has established recommendations8 for dietary, lifestyle, and pharmacologic interventions to lower

1933-2874/$ -see front matter © 2007 National Lipid Association. All rights reserved. doi:10.1016/j.jacl.2007.10.004

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Plant sterols and combination colesevelam/statin therapy

LDL-C to predetermined goals based on the CHD risk status of the patient. Despite overwhelming evidence supporting LDL-C reduction, one study9 has indicated that only 18% to 68% of patients achieve NCEP-specified LDL-C goals, with the lowest rate of 18% in patients with CHD. Since that study was published, even lower optional LDL-C goals have been recommended10 for patients with at least moderate CHD risk, resulting in a greater need for LDL-C–lowering modalities. To reach LDL-C goals, many patients may need to take more than one lipid-lowering product. The use of plant stanols/sterols to reduce LDL-C is an attractive option to both patients and practitioners because these products do not act systemically, have a limited sideeffect profile, and are readily available in over-the-counter food preparations. Particularly for patients already taking combination therapy to lower LDL-C, these agents offer potential for further LDL-C reduction with little concern for drug-to-drug interactions. The efficacy of stanols/sterols to incrementally reduce LDL-C when used with statins has been demonstrated.11-13 However, whether stanols/sterols are effective when used in combination with other lipidlowering agents, as may be commonly done in clinical practice, requires further evaluation. The objective of this study was to evaluate the effects of plant sterol-fortified orange juice (S-OJ), in combination with the bile acid sequestrant (BAS) colesevelam hydrochloride (HCl), on LDL-C in patients taking a stable dose of a statin.

Methods Patient population A total of 148 subjects, aged 18 to 89 years, were screened for participation, and 60 entered the study. Inclusion criteria included: dyslipidemia treated with a stable dose of statin for 3 months, calculated LDL-C ⬎100 mg/dL, triglycerides (TG) ⬍300 mg/dL, and weight stable within the last 3 months. Exclusion criteria included: diabetes mellitus, active liver disease, pregnancy, women of childbearing age not using birth control, inability to swallow large tablets/capsules, treatment with any other lipid-lowering agent (including gemfibrozil, fenofibrate, cholestyramine, colestipol, colesevelam HCl, plant stanols/sterols, ezetimibe, or omega-3 acids), ⬎12% variability between two screening calculated LDL-C values taken 2 weeks apart, history of bowel obstruction, abnormal thyroid-stimulating hormone level, and aspartate aminotransferase or alanine aminotransferase more than three times the upper limits of normal. The study was approved by the Colorado Multiple Institutional Review Board, and all subjects provided written informed consent.

Study design The study was a 10-week, randomized, double-blind, placebo-controlled parallel arm study. All visits took

627

place at the University of Colorado at Denver and Health Sciences Center Adult General Clinical Research Center. Subjects completed a screening visit at which height, weight, and waist circumference were recorded. Fasting serum lipids, apolipoprotein B (ApoB), high-sensitivity C-reactive protein (hs-CRP), electrolytes, kidney and liver function tests, blood glucose, thyroid-stimulating hormone, and a urinalysis were measured. Subjects who were not excluded by this first screening visit returned approximately 2 weeks later for a repeat serum fasting lipid panel, including ApoB and hs-CRP. Results from the two screening visits were averaged to serve as baseline values. Each subject’s dietary and alcohol intake was also collected via a computerized food frequency questionnaire at one of the screening visits by a licensed dietician from the General Clinical Research Center. The software package used by the dietitian was the Nutrition Data System for Research (Nutrition Coordinating Center, University of Minnesota, Minneapolis, MN). An intake of exercise was collected at the first screening visit by the study coordinator. Following enrollment, subjects remained on their statin therapy and were asked to take open-label colesevelam HCl (WelChol; Daiichi Sankyo, Inc., Parsippany, NJ) 1.875 g twice daily for the duration of the study. After 4 weeks of colesevelam HCl and statin combination therapy, patients were randomized to 6 weeks of additional treatment with 8 ounces twice daily of either: Minute Maid Heart Wise orange juice fortified with plant sterols (S-OJ; The Coca-Cola Company, Atlanta, GA) or placebo orange juice (P-OJ; Minute Maid Pulp-Free Premium, The Coca-Cola Company, Atlanta, GA). Minute Maid Heart Wise orange juice was selected because it has been shown previously to be effective at reducing LDL-C by 12.4%,14 is available commercially, and was believed to be a desirable food product for patients. The orange juices were identical in content, except for the additional 1 g plant sterols per 8 ounces of S-OJ. Patients were instructed to take the colesevelam HCl and orange juice at the same time twice daily with meals. Patients were also asked to follow manufacturer’s recommendations for refrigeration and were instructed to shake the contents before measuring their dose. The orange juices were repackaged in polyethylene containers, which have been used in a previous study and have not been found to affect the stability of the plant sterol.14 Through the entirety of the study, subjects were instructed to maintain their baseline dietary intake and exercise program. They were instructed to avoid drinking any additional citrus juices. Subjects were given 1-month quantities of colesevelam HCl and 2-week quantities of the orange juice at a time. Adherence was measured by pill counts and orange juice quantity measurements at each study visit and when subjects returned to pick up additional study medication. Adverse events were also documented at all study visits.

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Laboratory measurements

uated using a paired t-test. Fisher’s exact test was used to evaluate differences in the proportion of specific adverse events between groups. A P value ⬍ 0.05 was considered statistically significant for all statistical tests.

Lipid samples were assayed on the Olympus AU400e Chemistry Analyzer (Olympus American, Inc, Irving, TX). Intra- and inter-assay coefficients of variance were 0.85% and 1.54% for total cholesterol (TC), 0.50% and 1.12% for high-density lipoprotein cholesterol (HDL-C), and 0.82% and 2.18% for triglycerides (TG), respectively. The possible range for each assay was 25 to 700 mg/dL for TC, 20 to 175 mg/dL for HDL-C, and 15 to 950 mg/dL for TG. LDL-C values were calculated from the TC, HDL-C, and TG values using the Friedewald equation.15 High-sensitivity CRP samples were also performed on the Olympus AU400e Chemistry Analyzer. Intra- and interassay coefficients of variance were 1.10% and 1.83%, respectively. The possible range for hs-CRP was 0.2 to 20.0 mg/L, with a normal range of ⬍5 mg/L. Serum ApoB values were measured utilizing an immunochemical reaction assay (BN ProSpec, Dade Behring Inc, Newark, DE). Intra- and inter-assay coefficients of variance were 1.9% and 2.4%, respectively. The normal range for men was 55 to 140 mg/dL and for women was 55 to 125 mg/dL.

Statistical analysis Fifty subjects were calculated to be necessary to have 89% power to detect a 9% LDL-C difference between the S-OJ group and the P-OJ group at week 10, based on a standard deviation of 10%.16 A 9% LDL-C difference between groups was determined a priori to be the lowest clinically relevant LDL-C difference and a reasonably expected LDL-C reduction from the plant sterol. Sixty subjects were randomized to allow for a 20% dropout rate. Randomization was stratified based on age. Analyses are based on 56 complete cases at 4 weeks and 55 complete cases at 10 weeks. Statistical analysis was performed using SAS version 9.1 software (SAS Inc, Cary, NC). Variables were examined graphically for a normal distribution. Normally distributed data are presented as mean ⫾ standard deviation. Skewed data (TG and hs-CRP) are presented as median with lower and upper quartiles unless otherwise specified. TG and hsCRP were log-transformed prior to use in t- tests and the analysis of covariance model. Baseline characteristics were compared using two-group t-tests or ␹2 tests for independent proportions, as appropriate. The primary outcome of the study was the difference in LDL-C between groups at 10 weeks. Secondary outcomes were the change in LDL-C from baseline to week 4 and differences between groups in HDL-C, TG, hs-CRP, and ApoB values at week 10. Changes between baseline and week 4 were evaluated using a t-test on the paired difference for each subject. Differences between groups at 10 weeks for each measure were assessed using an analysis of covariance model, controlling for baseline values of the measure. Percent changes for outcome variables are listed as group mean or median percent change. Weight change from baseline to week 10 was eval-

Results Sixty patients were enrolled in the study. Fifty-six subjects completed the 4-week assessment, and 55 completed the 10-week assessment. Five patients withdrew from the study, four before initiating blinded treatment. Of the five patients who did not complete the study, one was due to missing scheduled study visits (male, P-OJ group), one was due to a protocol violation (statin dose changed, male, P-OJ group), and three were due to mild adverse events (1 female, P-OJ group; 1 female and 1 male, S-OJ group). Only one patient withdrawal, due to mild dyspepsia, was believed to possibly be related to study medication. Overall mean adherence to colesevelam HCl and orange juice was 92% and 89%, respectively. Mean adherence between the P-OJ and S-OJ groups was similar (P-OJ: 92% to colesevelam HCl and 89% to orange juice; S-OJ: 93% to colesevelam HCl and 89% to orange juice).

Baseline characteristics Subject demographics and baseline characteristics are shown in Table 1. Mean age was 57 ⫾ 10 years, and the majority were Caucasian (six patients were Hispanic/ Latino, three were African-American, and one was Asian). Baseline TGs were significantly higher in the S-OJ group (P ⫽ 0.04), but LDL-C and ApoB did not differ between groups. Daily alcohol intake was significantly higher in the P-OJ group (P ⫽ 0.04). There were no other significant differences between groups at baseline, including an analysis of baseline measures based on gender (data not shown). During the study, all subjects continued their previous statin treatment, which consisted of atorvastatin, lovastatin, or simvastatin. Nine, 15, and 6 patients in the P-OJ group and 10, 12, and 8 patients in the S-OJ group took atorvastatin, lovastatin, and simvastatin, respectively.

Effect of colesevelam HCl Four weeks of colesevelam HCl in combination with a statin significantly reduced TC, LDL-C, and ApoB measurements in the entire study population (Table 2). Percent decreases after adding colesevelam HCl at 4 weeks were 9.6%, 21.9%, and 8.5% for TC, LDL-C, and ApoB, respectively. Colesevelam HCl also significantly increased HDL-C and TG measurements by 6.2% and 18.8%, respectively. There was no significant effect from colesevelam HCl on hs-CRP. Of note, LDL-C concentrations after 4 weeks of colesevelam HCl were consistent and not signif-

Linnebur et al Table 1

Plant sterols and combination colesevelam/statin therapy

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Baseline characteristics

Characteristic Age (y) Male gender, n (%) Caucasian race, n (%) Body mass index Waist circumference (cm) Waist Umbilicus Iliac Framingham score (% 10-year CHD risk) Risk factors/past medical history, n (%) Smoking Hypertension Prior myocardial infarction Prior revascularization Prior transient ischemic attack or stroke Use of statins Statin dose (mg/day) TC (mg/dL) Calculated LDL-C (mg/dL) HDL-C (mg/dL) Men Women TG (mg/dL) Ln(TG) hs-CRP (mg/L) Men Women Ln(hs-CRP) ApoB (mg/dL) Alcohol intake (g/day) Saturated fat (g/day) Cholesterol (mg/day) Exercise n (%) Sedentary Minimum to moderate Trained

Sterol OJ (n ⫽ 30) 57.4 ⫾ 11.8 14 (46.7) 25 (83.3) 27.0 ⫾ 4.1 92.5 93.1 102.1 7.0

⫾ ⫾ ⫾ ⫾

10.8 14.5 8.7 6.2

Placebo OJ (n ⫽ 30) 56.4 ⫾ 7.8 16 (53.3) 25 (83.3) 29.2 ⫾ 5.7 96.4 98.5 105.4 6.0

⫾ ⫾ ⫾ ⫾

14.7 15.8 13.7 4.9

3 (10) 9 (30) 0 (0) 0 (0) 1 (3.3) 30 (100) 28.5 ⫾ 18.3 201.1 ⫾ 26.6 122.0 ⫾ 20.1 48.5 ⫾ 9.4 46.6 ⫾ 8.3 50.1 ⫾ 10.2 145.0 (105.5, 203.0) 5.0 ⫾ 0.4 1.3 (1.0, 2.0) 1.23 (0.9, 1.6) 1.34 (1.1, 4.2) 0.4 ⫾ 0.9 105.7 ⫾ 17.3 5.7 ⫾ 8.8 23.0 ⫾ 13.4 220.5 ⫾ 89.0

1 (3.3) 9 (30) 0 (0) 0 (0) 1 (3.3) 30 (100) 29.7 ⫾ 18.5 202.1 ⫾ 24.9 126.2 ⫾ 24.0 51.1 ⫾ 10.4 47.9 ⫾ 10.4 54.8 ⫾ 9.3 107.3 (91.5, 146.5) 4.7 ⫾ 0.4 1.9 (0.5, 2.7) 1.98 (0.6, 3.3) 1.54 (0.5, 2.4) 0.3 ⫾ 1.1 104.7 ⫾ 15.2 13.0 ⫾ 16.9 23.1 ⫾ 13.8 248.1 ⫾ 174.1

9 (30) 14 (46.7) 7 (23.3)

8 (26.7) 18 (60) 4 (13.3)

P value* NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS

* 0.04 *

NS NS 0.04 NS NS

NS

Values are presented as mean ⫾ SD or as the median (25th percentile. 75th percentile) for TG and hs-CRP. TG and hs-CRP were approximately log-normally distributed; all statistical tests were done on the natural log. ApoB, apolipoprotein B; CHD, coronary heart disease; HDL-C, high-density lipoprotein cholesterol; hs-CRP, highly sensitive C-reactive protein; LDL-C, low-density lipoprotein cholesterol; TC, total cholesterol; TG, triglycerides. *P values are based on two-group t-tests or ␹2 tests for independent proportions, as appropriate.

icantly different between those patients randomized to S-OJ compared to P-OJ.

Effect of colesevelam HCl and S-OJ An additional 6 weeks of S-OJ in combination with statin and colesevelam HCl therapy had no significant effect on any lipid or other outcome measures beyond that of colesevelam HCl (Table 2). LDL-C concentrations are depicted in Figure 1. The percent LDL-C reduction from baseline to week 10 was 21.1% with P-OJ and 19.7% with S-OJ (P ⫽ 0.74).

Achievement of LDL-C goal At baseline, on statin treatment, 71.7% of subjects were at their LDL-C goal based on NCEP guidelines.8 After 4 weeks of colesevelam HCl treatment, this number increased to 89.3%. With the addition of S-OJ, the percent of subjects at goal LDL-C did not increase but remained consistent. Overall, 89.1% of subjects reached their LDL-C goal at 10 weeks.

Adverse events and weight change Only one patient had a serious adverse event (nephrolithiasis), but it was not believed to be related to study treatments. No statistical differences were found in the pro-

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Table 2

Effect of orange juice and colesevelam hydrochloride treatment

Outcome measure

Baseline results (n ⫽ 60)

4-week results (n ⫽ 56)

P Value*

10-week results (n ⫽ 55)

P Value†

TC (mg/dL)

201.7 ⫾ 25.5

182.4 ⫾ 31.0

⬍0.0001

0.31

LDL-C (mg/dL)

124.1 ⫾ 22.1

96.9 ⫾ 25.6

⬍0.0001

HDL-C (mg/dL)

49.8 ⫾ 9.9

52.9 ⫾ 11.6

0.002

123.8 (97.5, 181.0)

147.0 (109.0, 224.0)

0.002

1.4 (0.8, 2.5)

1.4 (0.7, 2.1)

0.74

S-OJ: 180.6 ⫾ 31.9 P-OJ: 185.5 ⫾ 35.8 S-OJ: 98.0 ⫾ 27.5 P-OJ: 99.6 ⫾ 25.1 S-OJ: 48.9 ⫾ 10.1 P-OJ: 54.5 ⫾ 10.6 S-OJ: 137.5 (96.5, 222.5) P-OJ: 117.0 (98.0, 174.0) S-OJ: 1.4 (0.6, 2.2) P-OJ: 1.1 (0.6, 2.5) S-OJ: 94.1 ⫾19.3 P-OJ: 97.2 ⫾ 21.2

TG (mg/dL) hs-CRP (mg/L)

105.2 ⫾ 16.2

ApoB (mg/dL)

96.3 ⫾ 18.7

0.001

0.74 0.09 0.13 0.86 0.10

Values are presented as the mean value ⫾ SD or as the median (25th percentile, 75th percentile) for TG and hs-CRP. Triglyceride and hs-CRP were approximately log-normally distributed; all statistical tests were done on the natural log. ApoB, apolipoprotein B; HDL-C, high-density lipoprotein cholesterol; hs-CRP, highly sensitive C-reactive protein; LDL-C, low-density lipoprotein cholesterol; P-OJ, placebo orange juice; S-OJ, sterol-orange juice; TC, total cholesterol; TG, triglycerides. *P values for 4 week results are based on the difference in outcome for complete cases (n ⫽ 56) within subject from baseline to week 4 using a paired t-test. †P values at week 10 are based on the difference in outcome from baseline to week 10 using an analysis of covariance model, controlling for baseline values, using outcomes for complete cases (n ⫽ 55).

portion of S-OJ patients compared to P-OJ patients experiencing any type of adverse event. The most common adverse events were gastrointestinal-related, and included constipation, dyspepsia, diarrhea, gas/bloating, and nausea. Other adverse events reported included myalgia, fatigue, and headache. An increase in triglycerides to ⬎400 mg/dL (423 mg/dL) occurred in one subject in the S-OJ group and only at week 10.

160

Sterol - OJ

Placebo - OJ

140 LDL-C (mg/dL)

120 100 80 60

122.0 126.2

96.4

97.5

98.0

99.6

40 20 0

Baseline

Week 4

Week 10

Statin

Statin + Colesevelam

Statin + Colesevelam + OJ

Figure 1 Low-density lipoprotein cholesterol (LDL-C) concentrations after treatment with colesevelam hydrochloride (HCl) and orange juice. LDL-C concentrations at baseline, 4 weeks, and 10 weeks after treatment with colesevelam HCl alone (4 weeks) and sterol-orange juice (S-OJ; open bars) or placebo-orange juice (POJ; gray bars) in combination with colesevelam HCl /statin therapy (10 weeks). Data are presented as mean ⫾ SD.

Mean (⫾ standard deviation) change in weight during the 10-week study period for all patients was an increase of 0.27 ⫾ 1.8 kg (P ⫽ 0.3). There was no significant difference in weight change between groups or based on gender (data not shown).

Discussion In this study, we found that addition of S-OJ to statin/ colesevelam HCl therapy did not reduce LDL-C or affect any other lipid parameter compared to P-OJ in patients with dyslipidemia. As in previous reports,16-19 we found that colesevelam HCl added to statin therapy significantly reduced TC, LDL-C, and ApoB and significantly increased HDL-C. It is unlikely that an additional 2 weeks of colesevelam HCl therapy would have changed these outcomes, as previous data indicate that LDL-C reductions from 3.75 g/day colesevelam HCl are consistent and stable at 4 and 6 weeks after onset of treatment.20 In contrast to previous data,19,21 we did not find a significant effect from 4 weeks of colesevelam HCl on hs-CRP. This could be due to factors such as the shorter treatment course in our study, or differences in patient populations. The lack of effect on LDL-C that we found with combination S-OJ and colesevelam HCl is in contrast to a previous study22 of 11 patients that found additive reductions in LDL-C with the combination of simvastatin, stanol ester margarine, and cholestyramine. Our results are similar to a study23 in 33 men that found no significant reduction in LDL-C with sitostanol therapy in combination with cholestyramine compared to cholestyramine alone. However, the latter study also demonstrated a lack of effect from

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monotherapy sitostanol treatment, and the patient population differed in that they were required to consume a lowcholesterol diet and were not taking statins at baseline. We can only speculate why our study did not demonstrate additional LDL-C–lowering from plant sterols in combination with statin/colesevelam HCl therapy. It is possible that colesevelam HCl could have affected the fecal excretion of the plant sterols, that the order of treatments, or that dosing times of the products played a role. BASs bind bile acids, upregulating LDL-C receptors and production of bile acids to reduce serum LDL-C concentrations. Colesevelam HCl and cholestyramine are both BASs, but colesevelam HCl differs from other BASs in that it was engineered for specificity and high-capacity bile-acid binding. One source indicates that cholestyramine might also potentially increase fecal excretion of sterols,24 but it is unknown if colesevelam HCl has these same effects. Plant sterols act within the intestinal lumen to competitively displace cholesterol from mixed micelles, leading to reduced cholesterol availability for absorption.25 Thus, if colesevelam HCl increased the fecal excretion of the plant sterols, it is possible that they were not as available to competitively inhibit cholesterol absorption in the intestinal lumen. It is also possible that the order of introduction of cholesterol-reducing therapies in our study affected the results. In general, BASs have a larger effect on LDL-C (approximately 15% to 30% reduction)8 and plant stanols/sterols have a smaller effect on LDL-C (approximately 10% reduction).26 If initiating the plant sterol first and the BAS second, it may be possible to observe a positive effect of both treatments in a stepwise fashion, because the larger LDL-C reduction comes after an initial smaller reduction. In contrast, if a larger LDL-C reduction from BAS therapy comes first, the smaller reduction may not be readily observed. Our study introduced colesevelam HCl before the plant sterols, whereas the Gylling and Miettinen study22 introduced plant stanol esters before the cholestyramine. It is possible that the order of therapies could have affected the results. Of note, in the Gylling and Miettinen study, mean baseline LDL-C was approximately 104 mg/dL when the stanol ester was added.22 In our study, the mean baseline LDL-C was approximately 97 mg/dL, on statin and colesevelam HCl treatment, when the sterol was added. Although possible, it is unlikely that this small difference in baseline LDL-C accounted for the ability of the sterol to further affect LDL-C in the previous study. In our study, another potential reason for the lack of benefit from plant sterols is that patients were instructed to take their plant sterol and colesevelam HCl doses at the same time twice daily. In both the Gylling and Miettinen study22 and the Denke study,23 patients were instructed to separate their treatments. It is unclear if dosing colesevelam HCl and S-OJ separately would have impacted the results of our study, because there were conflicting effects on LDL-C in these previous studies.

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It is unlikely that the type, dose, or formulation of plant sterol, the diets of our patients, or the particular BAS used significantly affected the results of our study. The LDL-C– lowering with both plant sterols and stanols are reported as similar,26 2 g/day of plant stanols/sterols is reported as an effective dose,26 and S-OJ has been shown previously to reduce LDL-C by 12.4%14 when given as monotherapy. This is the first study that we are aware of studying the effects of sterol-fortified orange juice in combination with other drug therapies. Although it cannot be excluded that this S-OJ formulation had no effect, other stanols/sterols have shown LDL-C–lowering effects in combination with statins.11-13 We did not require our patients to follow a low-cholesterol, low-fat diet and, as such, mean daily cholesterol intake in our patients was not low. However, it is reported elsewhere that the effects of stanol/sterol esters on LDL-C are consistent regardless of the background diet of the patients,27 or may even be less effective in those following a low-cholesterol diet.23 Finally, our study utilized colesevelam HCl compared to cholestyramine. Both colesevelam HCl and cholestyramine similarly reduce LDL-C by binding bile acids and increasing conversion of cholesterol into bile acids. However, due to its structure, colesevelam HCl is less likely to cause drug interactions than cholestyramine.28 There are several potential limitations of our study. First, our study enrolled only 60 subjects and was prospectively powered to detect at least a 9% LDL-C difference between the S-OJ group and the P-OJ group at week 10. It is possible that our study failed to detect a smaller LDL-C difference between the study groups. However, given the lack of a trend toward greater LDL-C reduction in the S-OJ group, it is likely that a larger sample size would have yielded, at best, only a modest clinically significant reduction in LDL-C with S-OJ. Secondly, serum sterol (e.g., sitosterol and campesterol) concentrations were not measured in our study, so the extent of plant sterol absorption cannot be quantified. This potentially limits our ability to gain insight into the mechanism by which there was no effect of sterols. Another potential limitation of our study is that patients could take nutritional supplements during the study, and it is possible that the supplements could have interfered with the efficacy of the plant sterol. However, when reviewing the nutritional supplements that were reported to be taken by our patients, the supplements did not change during the study period for any patient, and they were not taken for treatment of cholesterol.

Conclusions In summary, due to increased focus on aggressive LDL-C reduction, patients may need additional lipid-lowering beyond statin therapy. The addition of plant stanols/ sterols to other typical lipid-lowering regimens may be

632 attractive to practitioners and patients because they are nonsystemic, readily accessible, and may be viewed as “natural” products. However, our results demonstrate that addition of plant sterols was ineffective at reducing LDL-C concentrations in patients already treated with statin and colesevelam HCl combination therapy. It is not clear why the addition of plant sterols did not result in additional efficacy, but it could be due in part to fecal excretion of the plant sterols induced by colesevelam HCl. Without other supporting data, plant sterols should not be recommended to patients treated with statin and colesevelam HCl combination therapy to further reduce LDL-C.

Financial disclosure Dr. Linnebur and Dr. Capell both received salary support from this study as part of a investigator-initiated research grant from Daiichi Sankyo, Inc. (Parsippany, New Jersey). Salary support was provided only for the first and second authors and for the study coordinator. Dr. Saseen is a member of the speakers bureau for Daiichi Sankyo, Inc. Active colesevelam HCl tablets were also supplied by DaiichiSankyo, Inc. Study design, management, data analyses, and manuscript preparation were completed by the investigators independently of the funding agencies. However, DaiichiSankyo reviewed the manuscript prior to submission. Dr. Eckel and Pamela Wolfe have no conflicts of interest to report related to this study.

Journal of Clinical Lipidology, Vol 1, No 6, December 2007

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Acknowledgments This study was registered with clinicaltrials.gov, Identifier NCT00249938. This study was also supported by the University of Colorado at Denver and Health Sciences Center Adult General Clinical Research Center, National Institutes of Health grant MO1RR00005. The authors would like to acknowledge Kathleen Morroni, RN, ANP-C, GNP, for her outstanding work as study coordinator.

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