PALM SPRINGS, CA — Research presented at the 2012 American Academy of Pain Medicine Annual Meeting highlighted an investigation to determine if topical opioids can relieve peripheral symptoms experienced by patients with intractable central pain. Central pain impairs the normal inhibition of descending pain signals that originate from the central nervous system, and thus, may be associated with allodynia, hyperalgesia, and flare pain.
Forest S. Tennant, MD, DrPH, Veract Intractable Pain Clinic, West Covina, CA, studied 37 patients (31–82 years old) with presumed central, intractable pain who were maintained on systemic opioids. Patients had constant pain for ≥2 years, had failed numerous peripheral treatments, and reported periods of allodynia and/or hyperalgesia. Topical treatments that have been used previously without benefit included Ben-Gay (75.7%; camphor, menthol, methyl salicylate), other topical antiinflammatory agents (40.5%), diclofenac (27%), gabapentin (21.6%), and herbal preparations (16.2%).
Treatment consisted of one or more of the following agents in a range of strengths dissolved in 1oz of cold cream: morphine 30–90mg; oxycodone 30–90mg; hydromorphone 8–24mg, or carisoprodol 350–1,050mg. Patients were instructed to use their topical preparations in a manner to maximize pain relief. Reasons cited by the patients to use their topical cream included: when aching begins (64.9%); flares (67.6%); when burning or itching begins (24.3%); to get out of bed each morning (29.7%); hurts to touch (16.2%); and helps sleep (43.2%).
Data was collected via written questionnaires completed after the patients had used their topical opioid for at least 90 days. All patients reported that pain relief occurred within ten minutes. The majority of patients (67.6%) experienced relief within 6–10minutes. Pain relief lasted for <1 hour in 32.4% of patients, 1–2 hours in 48.6%, 3–4 hours in 16.2%, and for >5hours in 2.7%.
Dr. Tennant concluded that topical opioids temporarily relieved troublesome symptoms associated with central intractable pain.