Administration to humans of ORG 21465, a water soluble steroid i.v. anaesthetic agent

Ten male volunteers received a 1-min i.v. infusion of a new water soluble steroid anaesthetic agent, ORG 21465. Individuals received doses ranging from 0.8 to 1.8 mg kg-1. All subjects experienced venous pain at the site of injection; those receiving 1.0 mg kg-1 or more became anaesthetized. There was no evidence of histamine release and apnoea did not occur. Excitatory phenomena were observed in all subjects and were dose related; no spikes were seen on the EEG. Pharmacokinetic analysis supported a three-compartment (non-weight- related) model with compartmental volumes V1, V2 and V3 of 4.31, 14.2 and 89.4 litre, respectively. Clearance from the central compartment V1 was 1.55 litre min-1. Inter-compartmental clearances Q1 and Q2 were 2.54 and 1.79 litre min-1. We found that ORG 21465 was an effective anaesthetic in humans. The relationship between sedation, anaesthesia and excitation requires further exploration.