Initial experiences with medicinal extracts of cannabis for chronic pain: results from 34 'N of 1' studies

Three Cannabis Based Medicinal Extracts (CBMEs) for sublingual use became available in 2000. A total of 34 'N of 1' studies were undertaken using this novel therapy for patients with chronic, mainly neuropathic, pain and associated symptoms to explore efficacy, tolerability, safety and dosages. Three CBMEs (Delta9 Tetrahydrocannabinol (THC), Cannabidiol (CBD) and a 1:1 mixture of them both) were given over a 12-week period. After an initial open-label period, the CBMEs were used in a randomised, double-blind, placebo controlled, crossover trial. Extracts which contained THC proved most effective in symptom control. Regimens for the use of the sublingual spray emerged and a wide range of dosing requirements was observed. Side-effects were common, reflecting a learning curve for both patient and study team. These were generally acceptable and little different to those seen when other psycho-active agents are used for chronic pain. These initial experiences with CBME open the way to more detailed and extensive studies.