Effect of time of administration of cholestyramine on plasma lipids and lipoproteins.

Cholestyramine was administered to 15 men with type II hyperlipoproteinemia in a dosage of 8 gm twice daily. For each subject, the p.m. dose was randomly assigned to one of four approximate time periods: mid-afternoon, 30 minutes before the evening meal, 60 minutes after the evening meal, and at bedtime. The time of the morning dose remained constant throughout the study. Each treatment period lasted eight weeks, and all participants completed all four treatment assignments. There was a significant reduction of both total plasma cholesterol (TPC) and LDL cholesterol (LDL-C) compared to baseline values (p less than 0.001) for all treatment regimens. TPC and LDL-C reduction was greatest when the p.m. dose was taken 30 minutes before the evening meal. This reduction was also significantly greater than when the p.m. dose was taken mid-afternoon (p less than 0.05). There was also a significant increase in triglycerides compared to baseline during all treatment periods (p less than 0.05). These findings indicate that the time of the p.m. dose of cholestyramine is important to obtain the maximum reduction of LDL-C. They also reveal that the most effective dosage schedule is administration immediately prior to the evening meal.