Effect of physostigmine on morphine-induced postoperative pain and somnolence.

The effects of physostigmine 1 mg i.v. were studied on the analgesia, sedation and reduction in respiratory rate induced by morphine 10 mg/60 kg i.v. in 10 patients recovering from surgery. Within 5-10 min, physostigmine abolished the somnolent effect of morphine and restored the respiratory rate to pre-drug values. Analgesia, assessed by an independent observer and by the patient was, if anything, increased by physostigmine. The analeptic effect of physostigmine lasted 40-60 min.