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

Study Overview
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Brief Summary
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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.

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

Conditions
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Postherpetic Neuralgia

Intervention / Treatment
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* Drug: MK-8291
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: MK-8291 → Placebo<br>In Treatment Period 1, participants were orally administered 10 mg MK-8291 once daily on Days 1 and 2, twice daily on Days 3 to 27, and once daily on Day 28 of the period. After Treatment Period 1, participants were to undergo a minimum of a 7-day Washout Period, which was followed by Treatment Period 2. In Treatment Period 2, participants were orally administered Placebo once daily on Days 1 and 2, twice daily on Days 3 to 27, and once daily on Day 28 of the period. (Total duration of treatment: up to approximately 63 days) | Drug: MK-8291<br>* MK-8291 oral tablets<br>Drug: Placebo<br>* Placebo oral tablets<br>|
| Experimental: Placebo → MK-8291<br>In Treatment Period 1, participants were orally administered Placebo once daily on Days 1 and 2, twice daily on Days 3 to 27, and once daily on Day 28 of the period. After Treatment Period 1, participants were to undergo a minimum of a 7-day Washout Period, which was followed by Treatment Period 2. In Treatment Period 2, participants were orally administered 10 mg MK-8291 once daily on Days 1 and 2, twice daily on Days 3 to 27, and once daily on Day 28 of the period. (Total duration of treatment: up to approximately 63 days) | Drug: MK-8291<br>* MK-8291 oral tablets<br>Drug: Placebo<br>* Placebo oral tablets<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change From Baseline in Pain Intensity at Week 4 of Each Treatment Period | Participants completed a pain intensity questionnaire, the Numerical Rating Scale (NRS), in the morning prior to taking study treatment at Baseline (Day 1) in each treatment period, and then daily up to Day 28 in each treatment period. The NRS assesses the intensity of Post-herpetic Neuralgia (PHN) pain during the preceding 24-hour period on an 11-point numeric rating scale (range: 0=no pain to 10=pain as bad as you can imagine). The mean score in pain intensity of Week 4 (Days 22 to 28) minus the mean score at Baseline is presented, with a negative change representing improvement (or reduction) in pain intensity. In comparison to placebo, a reduction (difference in the change from Baseline) of 1 on the 11-point NRS is expected. | Baseline and Days 22-28 of each treatment period (Up to approximately 63 days) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants Achieving a 30 Percent or Greater Change From Baseline to Day 28 in Pain Intensity | Participants completed a pain intensity questionnaire, the Numerical Rating Scale (NRS) in the morning before taking study treatment at Baseline (Day 1) in each treatment period, and then daily from Day 1 up to Day 28 in each treatment period. The NRS assesses the intensity of PHN pain during the preceding 24-hour period on an 11-point numeric rating scale (range: 0=no pain to 10=pain as bad as you can imagine). This was a binary outcome denoting whether the participant reported a percent change from Baseline to Week 4 (Days 22 to 28) in the mean pain intensity score greater than 30%. The percentage of participants who reported a 30% or greater change from Baseline to Day 28 of each treatment period is presented. | Baseline and Day 28 in each treatment period (Up to approximately 63 days) |