Clinical pharmacokinetics of nifedipine gastrointestinal therapeutic system

摘要: The pharmacokinetics of nifedipine following intravenous administration can be represented by an open two-compartment model with a terminal elimination half-life about two hours. Nifedipine is extensively biotransformed to inactive metabolites, and the total body clearance (450 700 ml/minute) primarily due hepatic metabolism. undergoes significant tissue distribution in that steady-state volume (0.62 0.77 liter/kg) more than twice central compartment (0.25 0.29 liter/kg). Although almost completely absorbed from gastrointestinal tract, oral bioavailability ranges 45 68 percent because first-pass given three times daily shows no accumulation plasma changes pharmacokinetic behavior during one-week study period. Pharmacokinetic studies on therapeutic system (GITS) show GITS dosage form (relative capsule) 65 after single dose, but increases 86 at residual absorption 24 hours dosing. Linear are seen doses as indicated dose-proportional area under drug concentration-time curve over range 30 180 mg. Administration presence food slightly rate absorption, does not influence extent bioavailability. Dose-dumping has been observed, even dosing meal containing high level fat. tablets provide zero-order delivery nifedipine, persists beyond interval Thus, will permit once-a-day maintain desired, constant concentration minimal fluctuation.