The primary aim of the phase 2 trial reported by Dr. Hunter was to assess ZYN002’s efficacy in managing osteoarthritis knee pain. Secondary objectives were to assess the gel’s safety and tolerability.
The STOP 1 (Synthetic Transdermal Cannabidiol for the Treatment of Knee Pain Due to Osteoarthritis) trial was a double-blind, placebo-controlled trial. For inclusion in the study, patients had to be between age 40 and 75 years and have had knee pain for at least 12 months because of primary OA, based on clinical and x-ray data as per American College of Rheumatology criteria. Anyone with a history of fibromyalgia or epilepsy was excluded.
A total of 320 patients with painful knee OA, with a mean age of 62 years, were randomized and underwent a 1-week washout period in which all their analgesic medications being used for osteoarthritis knee pain, except acetaminophen, were stopped. That was followed by a 7- to 10-day period when baseline daily worst pain levels were captured using a 0-10 numeric rating scale. Patients then underwent 12 weeks of treatment with either a high (500 mg) or a low (250 mg) dose of the gel, or placebo, given in twice-daily doses.