Author(s): David A L Newcombe, Natalie Walker, Janie Sheridan and Susanna Galea
Introduction: Cannabis users may also use tobacco products which increases the potential for drug-induced harm over and above that caused by one substance on its own. Therefore, a pharmacotherapy that treats dependence on both substances would be beneficial. Tetrahydrocannabinol and varenicline act at the α7 subtype of the nicotinic receptor and so it was hypothesised that varenicline may also effect cannabis use.
Methods: Five nicotine and cannabis dependent individuals (median age 37), who were attending a community alcohol and drug service, and who expressed a desire to quit tobacco smoking, were prescribed 12 weeks of varenicline and were followed up weekly for the first month, then fortnightly for as long as possible over this time.
Results: Four of the five cases reported reducing their use of both substances after commencing varenicline, and also of experiencing less enjoyment from using these substances. The remaining case withdrew early in the study due to a migraine. No participant reported taking varenicline for more than 6 weeks, and only one could be followed up for 12 weeks. The reasons reported by participants for ceasing varenicline included feeling flat, experiencing nausea and vomiting, feeling angry and being short tempered, and as a result of a variety of family stressors.
Conclusion: The administration of varenicline to cannabis users was associated with reductions in the enjoyment reported from using cannabis, and the amount of cannabis used. These results support further investigation of varenicline’s potential as a therapeutic intervention to treat dependence on nicotine and cannabis.
