The Efficacy of MK-8291 in Participants With Post-herpetic Neuralgia (PHN) With Allodynia (MK-8291-012)

A Randomized Clinical Trial to Study the Efficacy, Safety, and Tolerability of MK-8291 in Subjects With Post-Herpetic Neuralgia With Allodynia

This study aims to determine whether MK-8291 is effective in reducing pain in participants with post-herpetic neuralgia (PHN) with allodynia.

The primary hypothesis is that when compared to placebo, treatment with MK-8291 reduces the change from Baseline in participant-reported pain intensity by 1 on an 11-point numeric rating scale.

Inclusion Criteria:

• non-pregnant female (and/or partner) agrees to use two acceptable methods of birth control throughout the trial until 2 weeks after the last dose of treatment
• female is postmenopausal or surgically sterile
• has a clinical diagnosis of PHN with allodynia for at least 3 months duration after healing of rash
• has a body mass index (BMI) =< 35 kg/m^2, inclusive
• is in good health, with exception of PHN
• is on a stable dose for at least 30 days prior to screening if taking any of the following: opioids, non-opioids, paracetomol, non-steroidal anti-inflammatory drugs (NSAIDs), aspirin, antidepressants
• is a nonsmoker or has not used nicotine or nicotine containing products for at least prior 3 months

Exclusion Criteria:

• has a non-PHN chronic pain state
• has a history of clinically significant and inadequately treated endocrine, gastrointestinal, cardiovascular, hematological, hepatic, immunological, renal, respiratory, genitourinary, or major neurological (including stroke and chronic seizures) abnormalities or diseases
• has a history of malignant cancer
• has a history or presence of esophagitis
• has a history of significant multiple and/or severe allergies (e.g. food, drug, latex), or has had an anaphylactic reaction or significant intolerability to prescription or non-prescription drugs or food
• is positive for hepatitis B surface antigen, hepatitis C antibodies, or human immunodeficiency virus (HIV)
• had major surgery, donated or lost approximately 500 mL of blood within 4 weeks prior to screening
• has participated in another investigational trial within 4 weeks prior to screening
• has a history of risk factors for Torsades de Pointes, has hypokalemia or hypomagnesemia
• has a history or presence of clinically significant cardiac arrhythmia, taking substances with the target of reducing heart rate and or exercising endurance sports
• has had an injection of local anesthetics or steroids in the region affected by PHN, within 35 days prior to randomization
• anticipates using prescription and non-prescription drugs or herbal remedies during trial
• consumes excessive amounts of alcoholic or caffeinated beverages
• uses cannabis, any illicit drugs, or has a history of drug (including alcohol) abuse within 12 months of screening visit