Even a short treatment period can have an effect on neuropathic symptoms.
Injections of botulinum toxin type A relieve pain in an animal model of diabetic neuropathy, according to new research.
A second presentation at the meeting suggests that a combination of Ginkgo biloba extract and folate is superior to placebo in reducing symptoms of diabetic neuropathy, even though nerve conduction velocities are unaffected.
Dr. Zdravko Lackovic, from Zagreb University in Croatia, said, “We previously showed that botulinum toxin reduces hypersensitivity in a model of surgical neuropathy.”
His team’s current research involved what they considered an animal model that more closely represents diabetic neuropathy, he said. They injected alloxan subcutaneously into rats, and used those that developed blood glucose levels > 15 mmol/L after 5 days. “About 60% of the diabetic rats developed mechanical hyperalgesia,” which is similar to diabetic neuropathy, Dr. Lackovic noted.
Five days after they injected the plantar surface of the paw pad of diabetic rats with 5 or 7 U/kg of botulinum toxin, the animals became less sensitive to formalin injection, as demonstrated by reductions in flinches and shaking of the injected paw, compared with diabetic rats treated with saline instead of the toxin.
Mechanical sensitivity was also reduced in the diabetic rats treated with botulinum toxin, an effect that lasted 15 days.
“To our knowledge, this is the first demonstration that a single peripheral injection of botulinum toxin might have a long-lasting antinociceptive effect in diabetic neuropathy,” the investigators conclude in their meeting abstract.
For the research reported in the second presentation, Dr. Susanne Koeppen, from the University of Essen in Germany, and her colleagues recruited 60 diabetic patients with polyneuropathy. The subjects were randomly assigned to Ginkgo biloba extract (EGb), folate, both agents, or placebo.
EGb 50 mg and folate 15 mg and placebo were administered by IV for 14 days, then as tablets three times daily for 14 days (EGb, 80 mg and/or folate 4 mg or placebo).
Dr. Koeppen stated that, “We found out that all three active treatments were superior to placebo, with the best effect seen with the combination of folate and EGb.” “I think it is important to know that even a short treatment period can have an effect on neuropathic symptoms,” she added, even though there were no changes in electrophysiologic tests.
Reported at the American Academy of Neurology’s annual meeting in San Diego.
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