To compare amitriptyline and maprotiline in the treatment of painful polyneuropathy in diabetics and nondiabetics.
A double-blind, crossover trial of treatment with amitriptyline, maprotiline, and placebo. Treatment was given in randomized order for periods of 4 weeks. Each period was separated by a 1-week washout. The final dose was 75 mg/day for both amitriptyline and maprotiline.
Thirty-seven patients with diabetic and nondiabetic painful polyneuropathy.
The treatment effects were assessed by daily ratings of pain intensity on a 10-step verbal scale (0 = no pain and 10 = worst thinkable pain) and at the end of each treatment period by a global rating of the analgesic effect on a 5-step verbal scale (pain relief scale). For the assessment of depression, the Comprehensive Psychopathological Rating Scale (CPRS) was used.
Using the global assessment of pain relief at the end of each treatment period, 22 of 33 patients reported reduced pain on amitriptyline treatment compared with 14 of 33 patients on maprotiline treatment and 8 patients on placebo treatment (p < .0001 and p < .05 for amitriptyline and maprotiline, respectively, against placebo). Amitriptyline was slightly better than maprotiline (p < .05) [tested by repeated measures analysis of variance (ANOVA)]. The order in which treatments occurred and the diagnosis of diabetes or nondiabetes did not have any significant effect on the global rating of pain relief.
The mean values of the daily ratings of pain intensity showed that pain was more severe in the evenings than in the mornings and that diabetic patients reported worse pain than nondiabetics at baseline. The mean values of pain reduction as assessed with the 10-step verbal scale during the 4th week of treatment showed that amitriptyline and maprotiline were significantly better than placebo in relieving the pain (p < .0001 and p < .01, respectively, post hoc test according to Scheffé). However, there was no significant difference between the pain reduction of amitriptyline compared with maprotiline when assessing pain reduction with the 10-step verbal scale during the 4th treatment week. Nor was there a significant difference between diabetics and nondiabetics with regard to the effect of the drugs.
The clinical effect was not significantly correlated to plasma concentration of either amitriptyline and its active metabolite nortriptyline or maprotiline in the global or daily assessments. The effect of treatment was not correlated to any particular pain quality nor to the intensity of pain. Depression was noted in three patients who completed the medication trial, but the effect of treatment of pain and depression did not clearly correlate. The adverse side effects of amitriptyline and maprotiline were common, and in 5 patients the medication had to be discontinued because of severe side effects.
From the present results and the literature, it is concluded that tricyclic antidepressants with a pharmacologic profile similar to amitriptyline are the most effective drugs in the treatment of polyneuropathy pain in both diabetic and nondiabetic patients.