Reversal of sedation and respiratory depression after anaesthesia by the combined use of physostigmine and naloxone in neurosurgical patients.

A clinical trial of the combination of naloxone in a low dose (1-1.5 micrograms X kg-1 body weight) with physostigmine (0.5-1.0 mg i.v.) was made to elucidate whether this combination could reverse postanaesthetic overdosing in neurosurgical patients without increasing postoperative pain. The investigation was made following previous findings that physostigmine has analgesic properties in addition to its systemic antisedative and anticholinergic effects as well as a stimulatory effect on morphine-depressed ventilation. Altogether 198 neurosurgical patients were investigated. The results showed that postanaesthetic over-sedation can be safely treated by a combination of naloxone and physostigmine in the dosages named above, resulting in the rapid reversal of sedation, where opiates, neuroleptics and benzodiazepines have been used. In contrast, this combination has very little effect on sedation following the administration of agents such as halothane and isoflurane. In the great majority of patients (95%), the treatment resulted in excellent analgesia during the first postoperative hour. The incidence of nausea and vomiting was increased somewhat by this treatment, but these side-effects could be minimized by decreasing the rate of drug administration. Physostigmine is contra-indicated in patients having symptoms and signs similar to those of Parkinson's disease, and the dose of physostigmine should also be reduced to 0.5 mg i.v. in all patients over the age of 65.