Effectiveness of a Heated Lidocaine/Tetracaine Topical Patch for Pain Associated with Myofascial Trigger Points: Results of an Open-label Pilot Study

Objective: Evaluate potential usefulness of a heated lidocaine/tetracaine topical patch for treatment for pain associated with myofascial trigger points (MTPs). Background: Depth and duration of analgesia when patch is used as indicated, on intact skin to provide local dermal analgesia for superficial venous access and dermatologic procedures, suggest utility in relief of MTP-associated pain. Methods: In this open-label, single-center outpatient pilot study, patients with 1-month history of pain associated with up to 3 MTPs and average pain intensity 4 on 11-point scale applied 1 patch to each MTP for 4hours twice daily for 2weeks, followed by 2weeks with no treatment. Patients continued prescribed analgesic dosing regimens. Results: Twenty patients enrolled; 17 completed the study. At baseline, mean +/- SD average pain intensity was 6.3 +/- 1.56. This decreased by 33% to 4.5 +/- 2.31 (N=20) at the end of treatment; 40% of patients had clinically significant (30%) decrease, and 25% had substantial (50%) decrease. Pain interference with general activity, mood, normal work, and enjoyment of life decreased by 50% in 35% of patients; and with walking, sleep, and relationship by 50% in 50% of patients (N=20). Worst trigger point sensitivity improved in 45% of patients; 75% were satisfied or very satisfied with treatment; none required rescue medication. Twoweeks after stopping treatment, average pain intensity was 5.0 +/- 2.04; treatment benefit was maintained in 8 (40%) patients. The most common adverse event was erythema. Conclusion: The heated lidocaine/tetracaine patch has potential utility as a noninvasive pharmacologic approach for managing MTP pain. Further studies are warranted.