Comparative respiratory depression of tillidine and morphine.

Respiratory depression induced by tilidine was compared with that of morphine in a crossover study in 6 healthy subjects. Increments of tilidine, 150 mg/70 kg, and morphine, 10 mg/70 kg, were given intravenously and displacement of each subject's CO2 response curve was measured after each dose increment. Both tilidine and morphine caused dose-related displacement of the CO2 response curves to the right. Approximately 80 to 120 mg of tilidine can be expected to induce the respiratory depression of morphine, 10 mg, when given intravenously. Subjective effects after tilidine were qualitatively similar to those of morphine but were of longer duration with nausea and vomiting more frequent. The respiratory depression of both drugs was effectively antagonized by naloxone.