In 19 patients, minaxolone citrate, a water-soluble steroid anaesthetic agent, has been used as a continuous infusion to supplement nitrous oxide anaesthesia. The minimum infusion rate (MIR) was found to be 11.3 micrograms kg-1 min-1 for patients premedicated with morphine 10 mg i.m. and breathing spontaneously 66% nitrous oxide in oxygen. The cardiovascular and respiratory effects were similar to those described in a previous study for Althesin administered under comparable conditions. Recovery from minaxolone was prolonged compared with Althesin, and this may be related both to the water-solubility of the drug, and to its greater apparent volume of distribution.

N-acetylcysteine (NAC) is a known antioxidant. We therefore investigated NAC as an agent protective against O2 toxicity in the lung. Twelve dogs were anaesthetized with sodium pentobarbital and ventilated with 100% O2 for 54 h. Five were given diluent and 7 intravenous NAC (loading dose prior to 100% O2 ventilation of 150 mg.kg-1 and maintenance dose of 20 mg.kg-1.h-1). Every 6 h, physiological evaluation of the pulmonary circulation, mechanical properties, and gas exchange was performed. Post-mortem evaluation consisted of gross examination and weighing followed by light and electron microscopy. By both functional and structural criteria, NAC protected against the effects of 100% O2. The NAC group developed significantly less increase in pulmonary vascular resistance, arterial carbon dioxide tension (PaCO2) and lung wet weight, while dynamic compliance was greater. NAC also delayed the development of abnormal ventilation-perfusion relationships and was associated with reduced pulmonary white cell accumulation, with less evidence of alveolar and interstitial oedema. NAC may well be worthy of evaluation as a therapeutic agent in human diseases characterized by oxidant damage.