Sensory Phenotyping to Enhance Neuropathic Pain Drug Development (SPENDD): A Randomized, Double-blinded Cross-over Clinical Trial Aimed at Investigating Whether Bedside Quantitative Sensory Testing Can Predict Response to Analgesics.
The goal of this clinical trial is to determine whether quantitative sensory testing (QST) can be used to classify participants into pain sub-groups and predict who will respond best to certain pain treatments in participants with painful peripheral neuropathy. The analgesic effect is evaluated by measuring pain intensity and Patient Global Impression of Change (PGIC). This study is a 3-period cross-over trial. This means researchers will compare 3 different drugs (pregabalin, duloxetine, and placebo) over a period of 19 weeks. Participants will: * Undergo a quantitative sensory testing (QST) exam. * Provide a blood sample. * Complete questionnaires on the computer. * Take the study drug as instructed.
∙ Patients eligible for inclusion in this study must fulfill all of the following criteria:
• Between 18 and 80 years old (inclusive).
• Have a diagnosis of peripheral neuropathic pain in both feet from generalized distal sensory polyneuropathy based on the following criteria
‣ A history of a relevant lesion of the peripheral nervous system, disease, toxic exposure, or no known cause (i.e., idiopathic).
⁃ Pain distribution in a neuroanatomically plausible distribution consistent with a symmetrical generalized polyneuropathy (i.e., with a glove and stocking distal to proximal gradient).
⁃ DN4 score≥ 4
• Have experienced the neuropathic pain in the feet for at least 6 months.
• Have at least one of the following sensory signs upon clinical examination: abnormal pinprick perception, allodynia, hyperalgesia, abnormal light touch perception, abnormal vibratory perception, or abnormal proprioception.
• Have average daily baseline worst pain intensity in their feet of 4 or greater and less than 10, on a 0-10 numeric rating scale of pain intensity (0 = no pain, 10= most intense pain imaginable) as measured on the daily diary during screening from at least 5 measurements.
• Able to understand and read English. This requirement is to ensure that participants can provide informed consent and complete PROs.
• Have been on stable dosages of all pain medications or using all non-pharmacologic treatments for neuropathy pain at consistent frequency for at least 1 month and willing and able to stay on those dosages (or use those frequencies) (except acetaminophen rescue) throughout the duration of the study.
• If taking cannabinoid products for any reason, must be at stable dosages for at least 1 month prior to the screening visit and willing to stay on that dosage for the duration of the study.
• Willing and able to complete electronic patient-reported outcomes at home using a REDCap link.