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

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.

Each group will undergo two 4-week treatment arms separated by a 4-week wash-out period. Participants will apply 1 hydrogel patch on both the right-sided and left-sided neck and shoulder girdle on the skin overlying a myofascial trigger point. No more than 2 patches will be used on each subject per treatment. During each 24-hour period, the patches will be placed on the skin for 12 hours and will be removed for 12 hours. Placebo hydrogel patches will be 2.5 cm in diameter with a breathable cloth backing. The experimental patches will be identical to placebo patches except will contain capsaicin 0.1% (500 mcg).

Each group will undergo two 4-week treatment arms separated by a 4-week wash-out period. Participants will apply 1 hydrogel patch on both the right-sided and left-sided neck and shoulder girdle on the skin overlying a myofascial trigger point. No more than 2 patches will be used on each subject per treatment. During each 24-hour period, the patches will be placed on the skin for 12 hours and will be removed for 12 hours. Placebo hydrogel patches will be 2.5 cm in diameter with a breathable cloth backing. The experimental patches will be identical to placebo patches except will contain capsaicin 0.1% (500 mcg).

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.