After intravenous administration of 3,6-dinicotinoylmorphine (nicomorphine) 30, 20 and 10mg to patients undergoing surgery, this agent is rapidly metabolised into the metabolites 6-mononicotinoylmorphine (6MNM) and morphine. The elimination half-lives are 1 minute for nicomorphine, 13 minutes for 6MNM and 120 minutes for morphine. Morphine is subsequently metabolised into morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G). The half-life of these 2 glucuronide conjugates is similar, about 225 minutes. A glucuronide conjugate of 6MNM was not detected. The area under the serum concentration-time curve of nicomorphine and its metabolites is linearly related to the dose.