Pharmacokinetics of intramuscular nicomorphine and its metabolites in man.

After i.m. injection nicomorphine is relatively slowly absorbed from the muscular depot and is found in the serum for approximately 1 h. The rate of absorption differs between patients and governs the overall pharmacokinetic profile of the compound. The relative AUCs were nicomorphine 18%, 6-nicotinoylmorphine 17%, and morphine 65%. Nicomorphine and 6-nicotinoylmorphine have significantly higher AUCs after i.m. injection than after i.v. injection, while the AUC of morphine and the total AUC show no difference between the two modes of administration.