Combination Spray Relieves Diabetic Neuropathy Pain
Combination Spray Relieves Diabetic Neuropathy Pain
February 20, 2009
By Heidi Splete
Elsevier/International Medical News Group
A combination of sodium valproate and a glyceryl trinitrate spray significantly improved pain in adults with diabetic neuropathy, based on data from a randomized, double-blind study.
Existing drug treatment strategies for diabetic neuropathy have been unsatisfactory because of associated side effects and complications, wrote Dr. R.P. Agrawal and colleagues at the Diabetes Care and Research Centre at S.P. Medical College in Bikaner (India).
In the current study, the researchers tested the effects of a glyceryl trinitrate (GTN) spray and sodium valproate on the pain scores of 83 type 1 or type 2 diabetes patients with histories of diabetic neuropathy.
“We have adopted a novel plan by combining two drugs of different groups acting by separate [mechanisms] so as to achieve maximum effect with minimum side effects,” they wrote. The results are published in the March issue of Diabetes Research and Clinical Practice (2009;83:371-8)».
The patients were divided into four groups and received one of the following combinations: sodium valproate and GTN spray (group A); placebo and GTN spray (group B); sodium valproate and placebo spray (group C); or a placebo drug and placebo spray (group D). Pain was assessed at the start of the study and each month for 3 months thereafter.
Only patients with at least one typical symptom of diabetic neuropathy, such as burning, numbness, cramping, or paresthesia, were included, and all of the participants stopped taking any drugs for painful neuropathy for at least 2 weeks before starting the study. In the treatment groups, the sodium valproate dose was 20 mg/kg per day» and the GTN spray was applied in one spray (0.4 mg) to each leg before bedtime.
After 3 months, all three treatment groups showed significant improvement in pain scores, compared with the placebo group. The average visual analog score (VAS) dropped from 7.60 to 5.05 in group A, from 7.75 to 4.95 in group B, from 8.00 to 6.15 in group C, and from 7.35 to 6.90 in group D.
Changes in scores on the McGill pain questionnaire, present pain intensity scores, and 10-point Likert scale scores also improved significantly in the treatment groups, compared with the placebo group. The numbers needed to treat, based on VAS pain parameters, were 7, 5, and 4 for sodium valproate alone, GTN alone, and the combined therapy, respectively.
Although all three treatment groups showed significant improvements in pain, compared with baseline scores, only the sodium valproate/GTN spray group (group A) showed significant improvements in two types of nerve response – median motor nerve distal latency and mean amplitude related to distal – based on electrophysiologic measurements.
The side effects of the treatment were minimal. One patient withdrew from the study because of persistent pain, one withdrew because of lack of compliance, and one withdrew because of a foot ulcer.
The patients seemed able to achieve maximum pain relief with minimal side effects with the drug combination, the researchers said. But more research is needed to determine whether lower doses of the two drugs in combination can achieve greater pain relief than lower doses of each drug separately, they added.
The researchers stated that they had no financial conflicts to disclose.
Copyright ©2008 Elsevier/International Medical News Group
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