Pilot Study of High-Concentration Capsaicin Patches in the Treatment of Painful HIV-Associated Neuropathy

Inclusion Criteria: Between 18 and 75 years of age. Documented evidence of HIV-1 infection. Painful HIV-associated neuropathy, whether resulting from HIV disease and/or antiretroviral drug exposure, with primary symptoms of pain, burning or dysesthetic discomfort in both feet for at least 2 months prior to Screening Visit. AND: Diminished ankle reflexes (compared to the knee) or absent ankle reflexes, AND/OR Distal diminution of either vibration sensation or pain or temperature sensation in the legs. Either no neurotoxic antiretroviral (i.e., didanosine [ddI], zalcitabine [ddC], or stavudine [d4T]) exposure for at least 8 weeks prior to Screening Visit, OR Currently on stable dose(s) of any of the neurotoxic antiretrovirals listed above for at least 8 weeks prior to Screening Visit, without a foreseeable need to change doses or medications for duration of study. Screening Pain Sum Score of 12 to 36. Intact, unbroken skin over the painful area(s) to be treated. If taking chronic pain medications, be on a stable (not PRN) regimen for at least 7 days prior to Treatment Visit (Day 0) and willing to maintain medications at same stable dose(s) and schedule throughout the study. Be willing and able to use Roxicodone® (oxycodone) oral solution, if needed, to relieve treatment-associated discomfort. Female subjects with child-bearing potential must have a negative urine or serum pregnancy test, to be performed at the Screening Visit. All subjects must be willing to use effective methods of birth control and/or refrain from participating in a conception process during the study and for 30 days following experimental drug exposure. Be willing and able to comply with protocol requirements for the duration of study participation. (Such requirements include, but are not limited to: completing a daily pain diary, attending all study visits, and refraining from extensive travel during study participation.) Exclusion Criteria: Presence of acute, active opportunistic infection, except oral thrush; oral, genital, or rectal herpes; and Mycobacterium avium bacteremia within 2 weeks prior to Screening Visit. Significant pain of an etiology other than painful HIV-associated neuropathy, for example, compression-related neuropathies, e.g., spinal stenosis, or fibromyalgia or arthritis. Subjects must not have significant ongoing pain from other cause(s) that may interfere with judging HIV-associated neuropathy pain. Evidence of another contributing cause for peripheral neuropathy, e.g., diabetes mellitus, hereditary neuropathy, vitamin B12 deficiency (B12 level less than or equal to 200 pg/mL) or less than 3 months of B12 supplementation prior to Screening Visit, or treatment within 90 days prior to Screening Visit with any drug that may have contributed to the sensory neuropathy. Any implanted medical device (spinal cord stimulator, intrathecal pump or peripheral nerve stimulator) for the treatment of neuropathic pain. Recent use (within 21 days preceding the Treatment Visit [Day 0]) of any topically applied pain medication, such as non-steroidal anti-inflammatory drugs, menthol, methyl salicylate, local anesthetics (including Lidoderm®), steroids or capsaicin products on the painful areas. Treatment for acute opportunistic infections within 14 days before Treatment Visit (Day 0). Maintenance treatment of cytomegalovirus (CMV) retinitis, Mycobacterium avium bacteremia, or cryptococcal meningitis is permitted. Current use of any investigational drug, or Class 1 anti-arrhythmic drugs (such as tocainide and mexiletine). Hypersensitivity to capsaicin (i.e., chili peppers or OTC capsaicin products), local anesthetics, Roxicodone or adhesives. Significant ongoing or untreated abnormalities in cardiac, renal, hepatic, or pulmonary function that may interfere either with the ability to complete the study or the evaluation of adverse events. Currently have active malignant disease. Malignancies in remission that do not require further treatment or Kaposi's sarcoma requiring local treatment only are allowed. High tolerance to opioids that precludes the ability to relieve treatment-associated discomfort with Roxicodone® if needed, as judged by investigator. History or current problem with prescription drug, illicit substance, or alcohol abuse from self report or as judged by investigator.