Pilot Study of High-Dose Capsaicin Patches to Treat Postherpetic Neuralgia Pain
A Double-Blind Controlled Pilot Study of High-Dose Capsaicin Patches in the Treatment of Pain Associated With Postherpetic Neuralgia
The purpose of this study is to gain initial information on the tolerability of high-dose capsaicin patches in patients with Painful Postherpetic Neuralgia. The study will also collect preliminary information on safety and efficacy.
Eligibility Criteria Inclusion Criteria: Patients may be eligible for this study if they: Have a diagnosis of Painful Postherpetic Neuralgia and are at least 6 months post vesicle crusting. Are in good health. Have an adequate pain score during the screening period. Have painful areas (maximum of two sites) below the neck. If female, are of non-childbearing ability as defined by absence of menses for a minimum of 3 months or surgically sterile. If male, are willing to agree to take adequate birth control precautions with their partner for 60 days following experimental drug exposure. Have unbroken skin with good perfusion over the painful area(s). Have the ability to feel capsaicin-mediated sensations, as evidenced by ability to feel topically applied OTC capsaicin cream. Are on a stable and continuous medication regimen, with no change in dosage for 21 days prior to study start, and are willing to maintain concomitant medications at current doses throughout the study. Are willing and able to use oral opioid-based analgesic agents for relief, in case this is needed to relieve acute pain associated with the application of capsaicin patches. Are 18 years of age or older. Are willing and able to comply with the protocol Exclusion Criteria: Patients will not be eligible for this study if they: Have diffusely distributed neuropathic pain (i.e., pain that is evident in more than 2 different sites). Subjects must not have significant pain outside the areas to be treated. Have any implanted medical device (spinal cord stimulator, intrathecal pump or peripheral nerve stimulator) for the treatment of neuropathic pain. Currently (within the past 21 days) use topically applied non-steroidal anti-inflammatory drugs, local anesthetics, steroids or capsaicin products on the painful areas. Currently (within the past 21 days) use topical agents such as lidoderm patch 5%, topical steroids or aspirin. Have a history or current problem with prescription drug or illicit substance abuse (from self report or as judged by investigator). Currently have an abuse problem with alcohol (from self-report or as judged by investigator). Are suspected of psychosocial gain/benefit of continued pain as judged by the investigator or primary treating physician. Plan to travel more than 100 miles from home during the study or engage in unusual activities that might exacerbate pain. Have poor cardiac, renal, hepatic, or pulmonary function judged by the investigator or primary treating physician. Have a laboratory value at screening outside the normal range, unless it is judged by the investigator as not clinically significant after appropriate evaluation. Have hypersensitivity to capsaicin (i.e., chili peppers or OTC capsaicin products), local anesthetics, oral opioid-based analgesic agents, or adhesives. Have a high tolerance to opioids. Currently using Class 1 anti-arrhythmic drugs (such as tocainide and mexiletine).