Trial to Evaluate the Efficacy of Topical Capsaicin to Reduce Pain and Improve Health-related Quality of Life in Adults With Chronic Myofascial Neck Pain

Double-blinded, Cross-over Randomized Controlled Trial to Evaluate the Efficacy of Topical Capsaicin to Reduce Pain and Improve Health-related Quality of Life in Adults With Chronic Myofascial Neck Pain

Chronic neck pain is a common condition that can negatively impact quality of life. Substance P is one of the chemicals in the body that can transmit pain signals from overloaded neck muscles to the brain. Topical capsaicin blocks the action of Substance P by releasing, and subsequently depleting the body's store of Substance P in the nerves. Topical capsaicin has been reported to be an effective therapy for a number of persistent pain conditions including diabetic neuropathy, post-herpetic neuralgia, osteoarthritis, rheumatoid arthritis, and post-mastectomy pain. This study will evaluate the efficacy of topical capsaicin to reduce pain and improve health-related quality of life in adults with chronic muscular neck pain.

The study will employ a double blinded randomized controlled cross-over trial design. A total of 60 patients aged 18-65 with at least 3 months of myofascial neck pain will be recruited to participate in the study. The participants will be randomized into two groups. Each group will undergo two 4-week treatment arms separated by a 4-week wash-out period. Participants will apply a topical gel patch 12 hours each day overlying painful areas in the neck and shoulder girdle for each 4-week period. The topical gel patch used in each arm of the study will be identical except the placebo will not contain the active ingredient, 0.1% capsaicin. Both topical gel patches will be supplied by Caleb Pharmaceuticals. Each participant will complete 3 surveys at baseline and after each 4-week treatment arm: 1) McGill Pain Scale, 2) visual analog scale, and 3) Short Form 36 (general quality of life data). Paired T-tests will be used to evaluate for statistically significant changes between treatment with the control gel versus the active ingredient gel containing the capsaicin.

Inclusion Criteria:

• Adults over 18 years of age
• Speak, read, and write English who have greater than 3 month duration of myofascial neck pain.

Exclusion Criteria:

• Patients who have used capsaicin in the last 4 months and patients with allergy to capsaicin
• Rash/infection overlying neck and shoulder girdle area
• Radiculopathy or structural abnormalities in the area being treated
• Unstable underlying diseases such as cardiovascular, hepatic, renal and CNS disorders will be excluded from the study
• Pregnant or breast-feeding women will not be allowed to participate in the study, and women of child bearing age will be using an effective method of birth control.