Science Cannabis

208 THE SCIENCE OF MARIJUANASome of the acute effects of the drug, however, including unpleasantpsychic reactions, intoxication, and temporary impairments in skilledmotor and cognitive functions, limit the usefulness of THC as a medicine.There appears to be only a narrow window between the desired andthe undesired effects.3. Because of the cardiovascular effects of THC and its propensity tomake schizophrenic symptoms worse, patients with cardiovascular diseaseor schizophrenia are not suitable subjects for cannabis-based medicines.As with most other CNS drugs, cannabis use should be avoided duringpregnancy.4. The safety of smoked marijuana is far more questionable. It causeschronic bronchitis in a substantial proportion of regular users, and therisk that in the longer term an association may be found with cancers ofthe respiratory tract makes it unsafe to recommend for any long-term use.The compassionate use of smoked marijuana in certain categories ofseverely ill patients may, nevertheless, be justified.5. In all instances, including the use of smoked marijuana, moreproperly controlled clinical trials are needed and research on improvedmeans of delivering the drug is also of high priority.The Institute of Medicine (1999) in their report Marijuana and Medicinesummarized the safety issues succinctly:Marijuana is not a completely benign substance. It is a powerful drug witha variety of effects. However, except for the harms associated with smoking,the adverse effects of marijuana use are within the range of effects toleratedfor other medications.