[Ritanserin prolongs the analgesic effect of morphine and slows the development of tolerance].

The effect of 5-HT2 receptor blocker ritanserine on the analgesic effect of morphine was studied in experiments on mice. A single simultaneous injection of ritanserine (10 mg/kg) and morphine (1, 10, and 20 mg/kg) prolonged the duration of analgesia in the tail clip test. Combined subchronic (6 days) injection of morphine and ritanserine (1, 5, and 10 mg/kg) twice a day delayed the development of tolerance to the opiate analgesic effect in the hot plate and tail clip tests.