CROSSOVER COMPARISON OF THE PHARMACOKINETICS OF AMLODIPINE AND FELODIPINE ER IN HYPERTENSIVE PATIENTS

The pharntacokinetics of amlodipine 5 mg and felodipine ER (extended r elease) 5 mg o.d. after single and 2 weeks of repeated oral doses, wer e compared in 25 essential hypertensive patients using a crossover des ign, As a secondary parameter the effects of the drugs on blood pressu re were assessed, Significant differences were found between all princ ipal pharmacokinetic variables, when comparing the 2 treatments after both single and repeated dosing. The coefficients of variation of maxi mal drug concentration and AUC after single dosing and at steady-state were significantly higher for felodipine ER than for amlodipine. Afte r repeated dosing the peak-to-trough plasma concentration ratio were 1 .58 and 4.43 (p < 0.001) for amlodipine and felodipine ER, respectivel y. Both drugs lowered systolic and diastolic blood pressure to the sam e extent after 2 weeks of repeated dosing. No significant differences between the blood pressure lowering vs time profile of the 2 drugs wer e encountered. In conclusion, the interpatient drug concentration vari ability and the peak-to-trough plasma concentration ratio were more fa vorable for amlodipine compared to felodipine ER. it remains to be est ablished whether these characteristics are also reflected in a more sm ooth and consistent blood pressure control.