Cannabinoids have a favorable drug safety profile.[1-4] Unlike opioid receptors, cannabinoid receptors are not located in the brainstem areas controlling respiration; therefore, lethal overdoses due to respiratory suppression do not occur. Because cannabinoid receptors are present in tissues throughout the body, not just in the central nervous system, adverse effects include tachycardia, hypotension,conjunctival injection, bronchodilation, muscle relaxation, and decreased gastrointestinal motility.
Although cannabinoids are considered by some to be addictive drugs, their addictive potential is considerably lower than that of other prescribed agents or substances of abuse. The brain develops a tolerance to cannabinoids.
Withdrawal symptoms, such as irritability, insomnia with sleep electroencephalogram disturbance, restlessness, hot flashes, and rarely, nausea and cramping have been observed, but these symptoms appear to be mild compared with withdrawal symptoms associated with opiates or benzodiazepines, and the symptoms usually dissipate after a few days.
Unlike other commonly used drugs, cannabinoids are stored in adipose tissue and excreted at a low rate (half-life 1–3 days), so even abrupt cessation of cannabinoid intake is not associated with rapid declines in plasma concentrations that would precipitate severe or abrupt withdrawal symptoms or drug cravings.
In clinical trials of Cannabis, euphoria is often scored as an adverse effect.[1,2]
In a retrospective cohort study of 64,855 men aged 15 to 49 years, participants were divided into cohorts based on their use of tobacco and marijuana: never inhaled either, inhaled only Cannabis, inhaled only tobacco, and inhaled tobacco and Cannabis. Among the nonsmokers, two cases of lung cancer werediagnosed during the follow-up period. Among the men who inhaled tobacco either alone or in addition to marijuana, the risk of lung cancer increased tenfold. In the follow-up of men who inhaled marijuana alone, no cases of lung cancer were documented.
A case-control study of 611 lung cancer patients revealed that chronic low Cannabis exposure was not associated with an increased risk of lung cancer or other upper aerodigestive tract cancers. A standardized questionnaire used during face-to-face interviews collected information on marijuana use expressed in joint-years, where 1 joint-year is the equivalent of inhaling one marijuana cigarette per day for 1 year. The results showed that, although using marijuana for 30 years or longer was positively associated in the crude analysis with each cancer type studied except pharyngeal cancer, no positive associations were found when adjusting for several confounders including cigarette smoking.
Furthermore, a systematic review assessing 19 studies that evaluated premalignant or malignant lunglesions in persons 18 years or older who inhaled marijuana concluded that observational studies failed to demonstrate statistically significant associations between marijuana inhaling and lung cancer after adjusting for tobacco use.
- Adams IB, Martin BR: Cannabis: pharmacology and toxicology in animals and humans. Addiction 91 (11): 1585-614, 1996. [PUBMED Abstract]
- Grotenhermen F, Russo E, eds.: Cannabis and Cannabinoids: Pharmacology, Toxicology, and Therapeutic Potential. Binghamton, NY: The Haworth Press, 2002.
- Sutton IR, Daeninck P: Cannabinoids in the management of intractable chemotherapy-induced nausea and vomiting and cancer-related pain. J Support Oncol 4 (10): 531-5, 2006 Nov-Dec. [PUBMED Abstract]
- Guzmán M: Cannabinoids: potential anticancer agents. Nat Rev Cancer 3 (10): 745-55, 2003. [PUBMED Abstract]
- Sidney S, Quesenberry CP Jr, Friedman GD, et al.: Marijuana use and cancer incidence (California, United States). Cancer Causes Control 8 (5): 722-8, 1997. [PUBMED Abstract]
- Hashibe M, Morgenstern H, Cui Y, et al.: Marijuana use and the risk of lung and upper aerodigestive tract cancers: results of a population-based case-control study. Cancer Epidemiol Biomarkers Prev 15 (10): 1829-34, 2006. [PUBMED Abstract]
- Mehra R, Moore BA, Crothers K, et al.: The association between marijuana smoking and lung cancer: a systematic review. Arch Intern Med 166 (13): 1359-67, 2006. [PUBMED Abstract]