Chlormethiazole has proved useful for prolonged sedation in patients receiving artificial ventilation of the lungs during intensive care. In short-term infusions sedation and unconsciousness can be produced quickly and reversal is rapid on stopping the administration. After prolonged infusion, however, recovery is much slower because of accumulation of the drug. The pharmacokinetics of chlormethiazole in both short and prolonged infusions were studied in four patients. Following brief administrations the drug disappeared very quickly from the blood as a result of re-distribution and the patients wakened after a few minutes. Unconsciousness was associated with plasma concentrations in the range of 3--5 micrograms ml-1. After 48 h administration, recovery was much slower, the elimination half-life varying from 3.5 to 12.1 h.

A 14-year-old boy suffered transient uniocular blindness after extraction of four permanent first molar teeth under general anaesthetic. We discuss the theoretical basis for ocular vasospasm secondary to the minor trauma of dental extraction being relayed to the orbit.