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.
A double-blind comparison of topical capsaicin and oral amitriptyline in painful diabetic neuropathy.
An 8-week double-blind, multicenter, parallel study compared the safety and efficacy of topical capsaicin and oral amitriptyline in patients with painful diabetic neuropathy involving the feet. Two hundred thirty-five patients were randomized to treatment with either capsaicin cream or amitriptyline capsules. Capsaicin-treated patients received inactive capsules, and amitriptyline-treated patients applied vehicle cream. A visual analogue scale of pain intensity and measurements of interference by pain with functional activities were recorded at onset and at 2-week intervals. A visual analogue scale of pain relief and physicians' global evaluation assessed changes in pain status from baseline. Topical capsaicin and oral amitriptyline produced equal and statistically significant improvements in pain over the course of the study. By the end of week 8, 76% of patients in each group experienced less pain, with a mean reduction in intensity of more than 40%. By the end of the study, the interference with daily activities by pain had diminished significantly (P = .001) in both groups, including improvements in sleeping and walking. No systemic side effects were observed in patients treated with topical capsaicin. Most patients receiving amitriptyline experienced at least one systemic side effect, ranging from somnolence (46%) to neuromuscular (23%) and cardiovascular (9%) adverse effects. Topically applied capsaicin is an equally effective but considerably safer alternative to amitriptyline for relief of the pain of diabetic neuropathy.