Reinforcing and subjective effects of the volatile anesthetic, sevoflurane

Sevoflurane is a volatile anesthetic that is chemically similar to volatile substances of abuse and can be safely administered to humans in laboratory research. In this study, the reinforcing and subjective effects of five concentrations of sevoflurane (0, 0.2, 0.4, 0.6, 0.8% sevoflurane in O2) were studied in 20 non-drug-abusers. During each of five sessions, subjects sampled a concentration of sevoflurane and 100% O2 (placebo) for 10 min each. Later, within the session, they chose nine times, once every 5 min, among sevoflurane (e.g. "Agent A"), placebo (e.g. "Agent B"), or neither (and were administered 100% O2, identified as "drug-free air"). Although "neither" was selected most frequently, mean preference ratios (sevoflurane choices/[sevoflurane choices+placebo choices]) and total sevoflurane choice peaked at the 0.4% concentration. Choice patterns varied across subjects, with some subjects never choosing sevoflurane and other subjects showing monotonic increasing or bitonic concentration-choice functions. Concentration-related increases in subjective effects were observed, including effects that are putatively associated with abuse liability. Ratings of drug liking and of wanting to inhale the drug again were positively correlated with sevoflurane choice. This study shows that sevoflurane can function as a reinforcer and produce abuse liability-related subjective effects in some healthy volunteers.