Science Cannabis

154 THE SCIENCE OF MARIJUANAsuffered from chronic untreatable pain arising from a variety of causes;these included multiple sclerosis, peripheral nerve damage, cancer, andback pain. Nabilone, given in doses up to 3 mg per day, provided usefulpain relief for 18 patients, 15 had equivocal results or were unable totolerate the drug, and 27 obtained no benefit. While a 30% success ratemight not seem impressive, these patients represented the worst problemsof the Pain Relief Service, and were reported not to respond to conventionalanalgesics or to placebo. The adverse side effects were drowsinessand unpleasant psychic effects, and these were sufficiently severe to leadseveral patients to abandon further use of the drug despite having obtainedsome pain relief. On the positive side, in addition to pain reliefsome patients reported that nabilone improved their sleep, relieved muscleand bladder spasms, relieved constipation, and led to increased relaxationand relief of anxiety and depression. A placebo-controlled trial ofnabilone in the treatment of pain has not yet been carried out.The usefulness of cannabinoids in the treatment of pain appears tobe limited. When given by the oral route the usual problems of variableand delayed absorption are compounded in this context by the very narrowwindow that seems to exist between a pain-relieving and an intoxicantdose of cannabinoid. However, it is worth bearing in mind thatmorphine and related opiate drugs are also powerful intoxicants, yet theyalso play a crucial role in the treatment of clinical pain despite the narrowwindow that exists between pain-relieving and intoxicant doses. Althoughthe usefulness of smoked marijuana in alleviating clinical pain isbased only on anecdotal reports from individual patients, it is not difficultto believe that this route of administration has many advantages over theoral route. Smoking delivers THC to the circulation rapidly —like anintravenous injection. It thus permits a more precise titration of plasmaTHC levels allowing some patients to achieve the desired effect of painrelief while avoiding unpleasant psychic side effects. Smoking marijuanacould be compared with a patient-controlled analgesia morphine pumpwith which patients self-administer morphine to the desired levels. Aswith many of the other potential medical indications for cannabis, therehave been no controlled trials with smoked cannabis, although there aremany individual anecdotes: