A systematic review of randomized clinical trials involving more than 1,000 patients found moderate-certainty evidence supporting vaporized THC and CBD for acute migraine and a standardized full-spectrum cannabis extract for chronic low back pain.
The study, published September 22 in Cannabis and Cannabinoid Research, examined five double-blind randomized controlled trials involving a combined 1,072 adults. Researchers evaluated isolated cannabinoids, synthetic cannabinoids, vaporized cannabis products and standardized cannabis extracts for low back pain, migraine and medication-overuse headache.
For acute migraine, vaporized tetrahydrocannabinol (THC) combined with cannabidiol (CBD) improved several key outcomes compared with placebo. Patients were more likely to experience pain relief two hours after treatment, complete freedom from pain and freedom from their most bothersome migraine symptom.
Some of the benefits were sustained for 24 to 48 hours. In contrast, a CBD-dominant formulation did not show a clear benefit. Researchers ultimately rated the evidence supporting vaporized THC-CBD for acute migraine as moderate certainty.
The review also found encouraging results for chronic low back pain. A phase III randomized trial examining VER-01, a standardized full-spectrum cannabis extract, found that the treatment improved pain intensity, disability, sleep quality and other patient-reported outcomes compared with placebo. The evidence supporting VER-01 for chronic low back pain was also rated as moderate certainty.
However, the findings varied significantly depending on the cannabinoid formulation and condition being treated.
For acute low back pain, a single 400-milligram dose of isolated oral CBD did not outperform placebo. Nabilone, a synthetic cannabinoid, produced favorable signals for pain and analgesic use among patients with medication-overuse headache and chronic musculoskeletal pain, but researchers classified that evidence as very uncertain.
THC-containing inhaled products were also associated with more psychoactive side effects. Researchers noted that those effects may have allowed some participants to determine whether they were receiving the active treatment rather than placebo, potentially weakening blinding in the trials.
Overall, the researchers said the evidence does not support treating cannabis-based medicines as a single class with a uniform effect on pain. Instead, effectiveness appears to depend on the medical condition, cannabinoid composition, formulation and method of administration.
The authors called for larger independent trials using standardized formulations, as well as additional research examining repeated cannabis treatment across multiple migraine attacks and longer-term safety.
The study was conducted by researchers affiliated with the Universidade de Campinas and Universidade Federal da Bahia in Brazil.
