Although both colestyramine and colestipol can moderately reduce absorption of propranolol, this does not seem to reduceits effects. Colesevelam does not appear to affect absorption ofmetoprolol.
5 g did not cause a clinically relevant alteration in plasma levels of sustained-release metoprolol 100mg (See reference number 1)
When 6 healthy subjects took a single 120mg dose of propranolol with a 10-g dose of colestipol peak plasma propranolol levels were raised by 30%. However, if an additional 10 g dose of colestipol was taken 12 hrs before propranolol peak plasma levels were decreased by 36 % and AUC was reduced by about 30%. No changes in blood pressure or pulse rates were seen (See reference number 2).
When 6 healthy subjects took a single 120mg dose of propranolol with an 8-g dose of colestyramine peak propranolol plasma levels were reduced by almost 25 % and AUC was reduced by 13%. An additional dose of colestyramine 12 hrs before propranolol reduced AUC by 43%. However,no changes in blood pressure or pulse rate were seen (See reference number 2). Preliminary results of another study found that colestyramine (single unstated dose) caused no significant changes in blood levels of propranolol in 5 patients with type II hyperlipidaemia taking propranolol 40mg four times daily (See reference number 3).
Uncertain. It seems probable that both colestyramine and colestipol can bind to propranolol in gut, thereby reducing its absorption.
Information is limited. Even though both colestyramine and colestipol can apparently reduce absorption of a single dose of propranolol, no changes in its effects were reported,(See reference number 2) suggesting that interaction is of minimal clinical importance. There is therefore no obvious reason for avoiding concurrent use. However,note that it is usually recommended that other drugs are given 1 hour before or 4 to 6 hrs after colestyramine, and 1 hour before or 4 hrs after colestipol.
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