A Guide To Topical Medications
Capsaicin is an alkaloid that depletes substance P from the terminals of unmyelinated C fibers, causing an initial burning and then analgesia. There have various studies with conflicting data about the benefits of capsaicin for diabetic neuropathy. Although it may help in the short term, long-term results have not been promising. Most authors feel that oral agents are likely to be more effective.
You would need to apply capsaicin cream (.025-.075%) three to five times daily, which can cause transient burning and erythema at the site of application.1
Topical lidocaine has become an ever increasingly popular treatment for neuropathic pain. Lidocaine gel and the 5% patch have been a very effective modality in treating pain associated with amputations, ulcers, scars and other neuritic conditions. A recent study showed some good results when the 5% patch was administered to patients with neuropathic pain.12
Isosorbide dinitrite (ISDN) is a vasodilator and a nitric oxide (NO) donor. Many researchers believe that low levels of nitric oxide may be a contributing factor in diabetic neuropathy.
Yuen, et. al., tested 22 diabetic patients with either ISDN spray or placebo spray for four weeks.13 The patients sprayed their feet once before bedtime with 30 mg. The researchers concluded that the ISDN spray helped overall neuropathic pain and burning sensation but had no effect on tingling, numbness, hyperesthesia or jabbing-like sensations. We have had no experience using this medication or any other sprays.
Painful diabetic neuropathy is often overlooked by many physicians as a minor problem. This cause serious disturbances with daily life activities and sleep. Treating podiatrists should be aware of the potential adverse effects and proper effective dosing regimens. At Forest Park Hospital, we are strong proponents in addressing the pain of the neuropathic patient. Although the TCAs and epileptic agents have been used for decades, we have found that the newer agents like Foltx and Folgard can be just as effective and safer.
All of the aforementioned agents may be used to treat not only diabetic neuropathy but also neuropathic pain associated with amputations, CRPS, painful malleolar ulcers and symptomatic scars.
Dr. Rampetsreiter and Dr. Abdo are surgical residents at Forest Park Hospital in St. Louis under the direction of Allen M. Jacobs, DPM, FACFAS.
Dr. Steinberg (pictured) is an Assistant Professor in the Department of Orthopaedics/Podiatry Service at the University of Texas Health Science Center.
Editor’s Note: For a related article, see “Expert Insights On Painful Diabetic Neuropathy” in the March 2003 issue.