LAS VEGAS – A topical mixture of amitriptyline and ketamine controls pain in a variety of skin conditions, even when more traditional options fail, according to Dr. Mark Davis, chair of the division of clinical dermatology at the Mayo Clinic in Rochester, Minn.
"We are getting patients off systemic narcotics with these mixtures," he said at Skin Disease Education Foundation’s annual Las Vegas dermatology seminar.
Lidocaine patches are allowing leg ulcer patients to drop narcotics, too, and are greatly helping those with erythromelalgia, an often-misdiagnosed condition involving intermittent and excruciating, burning pain in the feet, hands, and sometimes ears. "To have something topical [for such pain] is terrific," Dr. Davis said.
The Mayo Clinic uses topical amitriptyline and ketamine for brachioradial pruritus, erythromelalgia, rectogenital and perineal pain, and other localized skin pain recalcitrant to oral medications and other standard approaches. Dr. Davis and his colleagues recently published several reviews and retrospective studies on the use of topical pain relievers, including a recent article showing that more than half the patients who used topical amitriptyline-ketamine for pain reported substantial or complete relief (Pain Physician 2012;15:485-8).
Pharmaceutical companies are working to bring the combination to market, but it’s not yet available commercially, so Mayo Clinic dermatologists have their pharmacists compound it in two strengths – 2% amitriptyline and either 0.5% or 5% ketamine – using Lipoderm cream as the base, according to Dr. Davis. Patients apply the mixture three times daily. Why it works isn’t clear; the drugs have different and perhaps synergistic effects on skin pain.
"I try to get people to use it [the product] on small parts of the body, such as the hands and feet, and, in patients with brachioradial pruritus, both arms," said Dr. Davis. "I’ve never used it any more extensively than that; I am afraid patients would absorb too much ketamine," he said.
Of more than 1,000 Mayo Clinic patients who have tried the combination, "I’d say less than 1% has told me that they’ve ever had a side effect," he said. "I’ve had just two or three patients tell me they’ve gotten nightmares," a known effect of ketamine. "This is a product that has great promise," he noted.
Meanwhile, some erythromelalgia patients at the Mayo Clinic have been able to walk again after applying lidocaine patches to their feet, and the clinicians there consider the patches first-line treatment for the condition. "Many patients are well controlled just by using [the patches], and I don’t think I’ve come across any side effects in the hundreds of patients I’ve treated," Dr. Davis said. In the inherited form of the disease, which accounts for perhaps 5% of cases, erythromelalgia is caused by a genetic sodium channel glitch that keeps nerves in the skin firing once they are stimulated.
Lidocaine patches also are "really useful for patients with bad, painful ulcers; I use [them] over whatever wound care I am using," Dr. Davis noted. Sometimes these patients can discontinue, or at least reduce, their use of narcotics, he said.
Lidocaine helps with debridement, too. "For leg ulcers, our nurses take 4 x 4-inch gauze and soak it in lidocaine 4% solution, and leave it on the ulcer for about 20 minutes. We are usually able to debride those ulcers [after that] even if they were very painful to start," he said.
Dr. Davis has no relevant disclosures. SDEF and this news organization are owned by Frontline Medical Communications.