Nifedipine
Nifedipine. Dihydropyridine calcium-channel blocker — vascular Cav1.2 blockade with minimal direct cardiac effect. Immediate-release form has… Oral half-life 2.1 h.
Dihydropyridine calcium-channel blocker — vascular Cav1.2 blockade with minimal direct cardiac effect. Immediate-release form has rapid BP swings and reflex tachycardia (associated with mortality signal in MI patients) → extended-release preferred for hypertension. Used acutely for severe hypertension and Raynaud's.
PK: AN INTERNALLY CONTRADICTORY RECORD — A SUSTAINED-RELEASE PHARMACOKINETIC ROW WEARING AN IMMEDIATE-RELEASE LABEL. Its citation is an HPLC-MS/MS ASSAY-VALIDATION paper that dosed "nifedipine sustained release tablets", while this record own effect-compartment note says "Immediate-release nifedipine". The stored 7 h matches none of that paper three reported half-lives and all of them are ABSORPTION-LIMITED from a sustained-release tablet — true elimination is about 2 h. V 60 L and F 0.5 appear nowhere in it; its only 60 is the mobile phase "60:40, v/v". Everything moves to a real capsule-versus-intravenous crossover: "The F value was 44.5 + 7.5% ... for the swallowed" and "When nifedipine was administered intravenously the mean t1/2 beta was 2.063 +/- 0.24 h". The volume is the only human intravenous figure available, 0.738 L/kg, and it is from POST-CARDIAC-SURGERY PATIENTS rather than volunteers — flagged, and kept only because the resolver default would be worse. ka 0.4 is an order of magnitude too slow for a capsule peaking at 0.5 h.
Pharmacokinetics
- Oral — t½ 2.1 h · F 45% · Vd 51.7 L
Sources: PMID:3027587, PMID:2604495, PMID:1595912, PMID:3987180