Amitriptyline produces analgesia in the formalin pain test.

A dose of 20 mg/kg of amitriptyline reduced pain in the second phase of the formalin test, which is an animal model of long-lasting pain in humans. Since the analgesic effect was produced by a single dose, which is insufficient to produce an antidepressant effect, these results indicate that amitriptyline has analgesic properties that are independent of its antidepressant properties.