Distigmine and amitriptyline in the treatment of chronic pain.

Sixty-five patients attending a pain relief clinic were randomly allocated to treatment for 5 weeks with amitriptyline alone, distigmine alone, amitriptyline and distigmine started together, or addition of distigmine to preexisting treatment with amitriptyline. Forty-eight patients successfully completed the trial; the most common cause for withdrawal was dry mouth in the amitriptyline-alone group. Two parameters were measured: Pain intensity was measured at the beginning and end of the treatment, and the saliva flow was measured at the beginning and the end of the treatment. At the end of 5 weeks, treatment with a combination of amitriptyline (75 mg/day) and distigmine (10 mg/day) resulted in a 43% reduction of pain and no subjectively noticeable mouth dryness. Distigmine alone also decreased pain and increased saliva flow, sometimes to the point of discomfort, whereas amitriptyline alone, in this particular series, did not significantly reduce pain and produced unpleasant mouth dryness. The addition of distigmine to preexisting (and ineffective) amitriptyline treatment failed to relieve pain. We therefore conclude that a combination of amitriptyline and distigmine (both given ab initio) may be a useful therapy for chronic pain.