This update has provided additional confirmation on the effectiveness of antidepressants for neuropathic pain and has provided new information on another antidepressant - venlafaxine. There is still limited evidence for the role of SSRIs. Whether antidepressants prevent the development of neuropathic pain (pre-emptive use) is still unclear. Both TCAs and venlafaxine have NNTs of approximately three. This means that for approximately every three patients with neuropathic pain who are treated with either of these antidepressants, one will get at least moderate pain relief. There is evidence to suggest that other antidepressants may be effective but numbers of participants are insufficient to calculate robust NNTs. SSRIs are generally better tolerated by patients and more high quality studies are required.
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.