Colestyramine pharmacokinetics

A single-dose, crossover study in 6 healthy fasting subjects found that the simultaneous use of colestyramine 8 g modestly reduced the AUC of a single 400-mg oral dose of ibuprofen by 26% and reduced its maximum serum levels by 34%. The rate of absorption was also reduced. Conversely, colestipol 10 g had no significant effect on the pharmacokinetics of ibuprofen. ... 

Colestyramine does not appear to alter the pharmacokinetics of quinine. 

The anticoagulant effects of phenprocoumon and warfarin can be reduced by colestyramine, especially if the coumarin is given at the same time. An isolated report describes unexpected sensitivity to warfarin in a patient taking colestyramine, which was attributed to a possible reduction in vitamin K absorption with colestyramine. Colestipol did not alter the absorption or effect of phenprocoumon or warfarin and colesevelam did not alter the pharmacokinetics of warfarin. 

A randomised crossover study in 7 healthy subjects given acipimox 150 mg with three 4-g doses of colestyramine (taken concurrently, and then 8 and 16 hours later) found that the pharmacokinetics of acipimox were slightly but not significantly altered by the colestyramine. There would seem to be no good reason for avoiding concurrent use. 

Colestyramine does not alter the pharmacokinetics of clofibrate when both drugs are given at the same time. Similarly colestipol does not alter the pharmacokinetics of clofibrate or fenofibrate, and colesevelam does not alter the pharmacokinetics of fenofibrate. Colestipol can reduce the absorption of gemfibrozil if given at the same time, but not if administration is separated by 2 hours. A similar interaction occurs between bezafibrate and colestyramine... 

Over a 6-day period no clinically relevant changes in the pharmacokinetics of clofibrate occurred in24 healthy subjects, who were given daily doses of colestipol 10 g at the same time as clofibrate 500 mg. Colestyramine 4 g four times daily had no effect on the fasting plasma levels, urinary and faecal excretion, or the half-life of clofibrate in 6 patients taking 1 g of clofibrate twice daily. In this study, the morning and evening doses of colestyramine were taken at the same time as the clofibrate. ... 

The absorption of raloxifene is reduced by colestyramine, and their concurrent use is not recommended. No clinically relevant changes in raloxifene pharmacokinetics occur with alumini-um/magnesium hydroxide, amoxicillin, ampicillin or calcium carbonate. Raloxifene does not alter digoxin or methylprednisolone levels. Oral antibacterials, antihistamines, aspirin, benzodiazepines, H2-receptor antagonists, ibuprofen or paracetamol (acetaminophen) were used in clinical studies without any obvious effect on raloxifene levels. Smoking does not appear to alter the efficacy of raloxifene. 

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