There are several shortcomings to using smoked marijuana clinically:
- there is much public and government resistance to smoking marijuana
- medical marijuana lacks standardized composition and dosage
- it has effects outside of the therapeutic goals (ie, psychoactivity), and
- long-term exposure may increase risks to pulmonary health.
D9-Tetrahydrocannabinol (popularly referred to as THC) is the primary psychoactive constituent of marijuana (Cannabis sativa). THC is known to bind to two receptors in the human body.
- cannabinoid (CB1) receptors, located primarily in the brain, and
- CB2 receptors, located primarily in immune cells.
Synthetic cannabinoids can target one or both CB receptors, either by acting with them or blocking them. This control potentially allows for a great deal more therapeutic options than regular medical marijuana. Also, plant-based marijuana is not water-soluble, so it cannot be injected; not so with a synthetic cannabinoid.
Early Attempts at Synthesizing Cannabinoids
- With nantradol and levonantradol, Pfizer made early attempts at creating cannabinoid-based analgesics (pain-killers) and antienimics (anti-nausia medicine). While more potent than THC, and easier to administer, the drugs had too many side effects.
- Another potent Pfizer creation from the 1970’s, CP 55-940, played a crucial role in the discovery of receptor CB1 in 1988, and is still used in laboratory research.
Cannabinoids currently on the market in North America or Europe
- HU-211 (Dexanabinol) is used to treat endotoxic shock, ischemia, and head trauma.
- Dronabinol (Marinol) is a cannabinoid prescribed as an appetite stimulant, primarily for AIDS, chemotherapy and gastric bypass patients. It was also FDA approved as an anti-nauseant, in order to better address the nausea experienced after chemotherapy treatments.
- Nabilone (Cesamet) is a synthetic cannabinoid that mimics THC. It is used therapeutically to releave pain and nausea.
- Sativex is an nasal spray botanically derived from specially grown marijuana. Sativex is approved for multiple sclerosis patients, who can use it to alleviate neuropathic pain and spasticity.
- Rimonabant (Acomplia) is an anti-obesity drug which reduces appetite. It blocks the same receptors that cause the “munchies” among marijuana users.
The Future of Medical Analogs
With improved understanding of the functioning of the cannabinoid receptors has come increased interest and activity in creating more medically-useful cannabinoids, both from pharmaceutical companies and university researchers. Potential strategies include:
- synthesizing a cannabinoid that works together with an opiod for pain reduction,
- finding mechanisms to increase the antioxidant and immune-boosting qualities of cannabinoids, and
- creating drugs that block CB receptors.
References
- Anonymous. Undated. GW Pharmaceuticals. http://www.gwpharm.com/index.asp. Accessed October 6, 2008.
- Joy, J.E., Watson, S.J., Benson, J.A., Eds. 1999. Marijuana and Medicine: Assessing the Science Base. Washington, D.C.: National Academy Press.
- Pertwee, R.G. 2006. Cannabinoid pharmacology: the first 66 years. British Journal of Pharmacology; 147:S163–S171.
- Wiley, J.L. and Martin B.R. 2002. Cannabinoid pharmacology: implications for additional cannabinoid receptor subtypes, Chemistry and Physics of Lipids;121: 57-/63.
Estela Kennen - Estela is a doctoral student in Public Administration and a freelance writer and editor.
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