A phase 3, double-blind, randomized, placebo-controlled trial (RELIEF) illustrated that administration of TNX-102 SL (sublingual [SL] formulation of Cyclobenzaprine) is linked to a substantial decrease in pain and exhibits a good tolerability and safety profile among individuals battling fibromyalgia. The objective of Seth Lederman et al. was to assess the safety and effectiveness of TNX-102 SL taken once a night, in alleviating fibromyalgia, a condition characterized by chronic pain and debilitating symptoms.

A total of 503 volunteers (18 to 65 years old) were administered TNX-102 SL 2.8 mg for a duration of 2 weeks, followed by 5.6 mg for 12 weeks (n = 248), while another group of 255 patients received matching placebo. The major outcome of the study was to measure the alteration in the average weekly pain scores from the baseline at the end of the 14th week. Secondary outcomes incorporated evaluating daily sleep quality and scores for Sleep Disturbance and Fatigue, Patient-Reported Outcomes Measurement Information System (PROMIS), Fibromyalgia Impact Questionnaire Revised (FIQR), and Patient Global Impression of Change (PGIC).

Safety assessment was conducted by monitoring and recording any adverse events (Aes). The TNX-102 SL treatment resulted in a significantly greater reduction in daily pain compared to the placebo at week 14, with a mean change of -1.9 compared to -1.5, respectively. Although TNX-102 SL did not show a substantial enhancement in PGIC at week 14, it was linked with improvements in daily sleep quality, PROMIS scores, and FIQR scores.

Among the volunteers receiving TNX-102 SL, 59.7% reported treatment-emergent AEs, compared to 46.3% in the placebo group. The most common AEs were abnormal taste of the product (4.4% vs 0.4%, respectively), oral paresthesia (5.6% vs 0.4%, respectively), and oral hypoesthesia (17.3% with TNX-102 SL vs 0.4% with placebo). Patients diagnosed with fibromyalgia experienced a notable decline in daily pain and exhibited a favorable tolerability and safety profile when treated with TNX-102 SL.