Felodipine kinetics in healthy men.
In a randomized, crossover study, the absorption, distribution, and elimination of intravenous and oral felodipine were investigated in eight healthy men 22 to 31 years old. Felodipine was given as a 2.5 mg iv infusion over 30 minutes and as a 27.5 mg oral solution. Both doses were labeled with 25 microCi 14C-felodipine. Given as an oral solution, felodipine is rapidly (mean time to peak concentration 64 minutes; range 30 to 90 minutes) and completely absorbed. Presystemic elimination reduced the availability to 16% (range 10% to 25%). Felodipine kinetics can be described by a multicompartmental model with three distinct phases. The t1/2 for the initial phase was 6.4 minutes (range 1.7 to 10.4 minutes) and felodipine was distributed to a volume of 0.6 L/kg (range 0.4 to 0.9 L/kg), which approximately corresponds to the total body water. The second distribution phase reached pseudoequilibrium with a t1/2 of 1.6 hours (range 1.3 to 2.2 hours). The volume of distribution at the end of this phase was 9.7 L/kg (range 6.0 to 18.2 L/kg). The terminal phase had t1/2 of 10.2 hours (range 6.7 to 20.7 hours). The contribution of the three phases to the AUC was 15%, 40%, and 45% in the order of increased t1/2. Total body clearance of felodipine was 1.2 L/min (range 0.9 to 1.6 L/min). Within 72 hours after drug dosing, 62% to 81% of the felodipine doses were excreted in the urine and feces as metabolites. The rate of excretion by the kidneys had a biphasic pattern, with t1/2 values of 4 and 18 hours. Approximately 10% of the doses was excreted in the feces.
D000284:Administration, Oral; D000328:Adult; D005243:Feces / Q000032:analysis; D015736:Felodipine; D006207:Half-Life; D006801:Humans; D007263:Infusions, Parenteral; D007408:Intestinal Absorption; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D009543:Nifedipine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism; D011897:Random Allocation; D012996:Solutions
D012996:Solutions; D009543:Nifedipine; D015736:Felodipine