Comparison of the pharmacokinetics of chloroquine after single intravenous and intramuscular administration in healthy Africans

The pharmacokinetics of chloroquine were studied after intramuscular and intravenous administration of the drug to healthy African adults. Chloroquine was analysed in plasma using an h.p.l.c. method and pharmacokinetic parameters were derived from the concentration‐time data using a non‐linear computer programme. A two‐compartment open model was assumed. Chloroquine was rapidly absorbed from an intramuscular site, producing a plasma concentration‐time profile similar to that obtained after a 15 min i.v. infusion of a comparable dose. The pharmacokinetics of chloroquine after i.m. and i.v. administration were characterised by a long half‐life and a very large volume of distribution. There was no significant difference between the values of each parameter obtained from the different routes. It is suggested that the high Cmax obtained after i.m. and i.v. administration of chloroquine might contribute to its toxicity when these routes are used in treatment.