Glyceryl trinitrate spray in the management of painful diabetic neuropathy: A randomized double blind placebo controlled cross-over study

Objectives: Various drugs are effective in the management of painful diabetic neuropathy, but none is completely satisfactory. The objective of this study is to test the effectiveness and safety aspect of glyceryl trinitrate (GTN) in the management of painful diabetic neuropathy as a nitric oxide (NO) donor with local vasodilating properties in spray form. Design: Randomized double blind placebo controlled cross-over study. Methods: Fifty patients with painful diabetic neuropathy (type 2) were screened consecutively, out of which two were excluded (1 with HbA(1C) > 11 and one withdrew his consent). The remaining 48 were given either drug (group A) or placebo (group B) in the first phase. After thorough clinical assessment in the first phase, quantitative assessment of pain was done by McGill Pain Questionnaire, Visual Analogue Score, Present Pain Intensity and 11 point Lickerts Scale, at the beginning and after 4 weeks, followed by 2 weeks wash out period and thereafter receiving 4 weeks of cross-over regimen. Adverse drug effects were assessed periodically. Results: Of the 48 patients, five dropped out, two in group A and three in group B. Both groups A and B experienced significant improvement in pain score in their drug phase of trial, when compared to placebo phase of other group (p < 0.001). After crossing over the treatment arm, patients of group B observed significant improvement in all pain scores compared to group A (1) < 0.001). The numbers needed to treat (NNT) calculated on VAS as pain parameters came out to be 4. The drug was well tolerated by all the patients except palpitation and headache for some days in five patients. Conclusion: GTN spray, a well tolerated drug, provides significant improvement in painful diabetic neuropathy. These data provide a. basis for future trials for longer duration in a larger group of patients. (C) 2006 Elsevier Ireland Ltd. All rights reserved.