Lack of effect of colesevelam HCl on the single-dose pharmacokinetics of aspirin,atenolol, enalapril,phenytoin, rosiglitazone,and sitagliptin

Aims

Drug interactions with bile acid sequestrants are primarily due to the potential of these agents to bind to concomitant drugs. Six clinical studies were performed to determine the effects of colesevelam on the pharmacokinetics of aspirin, atenolol, enalapril, phenytoin, rosiglitazone, and sitagliptin.

Methods

All six studies enrolled healthy subjects aged 18–45 years. The phenytoin study used a single-dose, three-period crossover design (phenytoin alone, phenytoin simultaneously with colesevelam, and phenytoin 4 h before colesevelam). The other studies used a two-period crossover design (test drug alone and test drug simultaneously with colesevelam). Colesevelam (3750 mg once daily) was dosed throughout the pharmacokinetic sampling period. After each single dose of the test drug, serial blood samples were collected for determination of plasma drug concentrations and calculation of pharmacokinetic parameters.

Results

For all six test drugs, 90% CIs for geometric least-squares mean ratios of AUC and C_max for the measured analytes were within specified limits, indicating no interaction between the test drug and colesevelam.

Conclusions

Aspirin, atenolol, enalapril, rosiglitazone, and sitagliptin may be taken with colesevelam. Although the phenytoin study indicated no pharmacokinetic interaction, phenytoin should continue to be taken ≥4 h before colesevelam in accordance with current prescribing information.