Pharmacokinetics of verapamil in overdose.
The information on the pharmacokinetics of verapamil in overdose is scanty. We report two adults who ingested 3.2 g and 4 g of verapamil, respectively. Both patients had hypotension and a severe bradycardia. The highest plasma verapamil concentration in these patients was about 2200 ng/ml and 2700 ng/ml, respectively. The decline in plasma verapamil and norverapamil concentrations followed first-order kinetics, and the half-life of verapamil was 7.8 h and 15.1 h, respectively. The free fraction of verapamil (non-protein bound) was higher at total concentrations exceeding 2000 ng/ml (12-15%) than at lower concentrations (2-6%). There seems to be no marked saturation of the metabolism of verapamil in acute poisoning. The apparent concentration-dependent changes in the free fraction may be due to therapeutic measures.
Kivistö
K T
KT
Department of Clinical Pharmacology, University of Helsinki, Finland.
Neuvonen
P J
PJ
Tarssanen
L
L
D000328:Adult; D002121:Calcium Channel Blockers / Q000493:pharmacokinetics* / Q000506:poisoning*; D062787:Drug Overdose; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D011041:Poisoning / Q000378:metabolism; D014700:Verapamil / Q000031:analogs & derivatives / Q000493:pharmacokinetics* / Q000506:poisoning*
D002121:Calcium Channel Blockers; C016904:norverapamil; D014700:Verapamil