Epilepsy, cannabinoids

The effects of cannabis on seizures is, at best, unpredictable. Although some cannabinoids have antiseizure effects, tolerance rapidly develops. Further, rebound hyperexcitability following THC administration may render these benefits impractical. Indeed, cannabinoids facilitate seizures and kindling in many studies. Certain isolated cannabinoids may eventually prove useful for treating seizures, but cannabis as a whole is not effective. In light of this, individuals with epilepsy are strongly recommended to avoid cannabis. 

Cannabinoids have been used for over 4,000 years as a sedative, a remedy for relief of pain, epilepsy, and asthma, and in religious ceremonies. The Spanish brought Cannabis sativa to the Americas, and Mexican laborers introduced the drug into the southern portion of the United States around 1910. The plant has been used for its fiber (called hemp) content for over 2,000 years. Early American settlers grew the plant for its hemp... 

Delta-9-THC and some synthetic analogs are used therapeutically, for example, for nausea and vomiting produced by antineoplastic chemotherapy, analgesic, anticonvulsant for epilepsy, anti-inflammatory agent, appetite stimulant for patients with AIDS, as well as treatment for conditions such as asthma and glaucoma. Synthetic cannabinoids used therapeutically include dronabinol, nabilone, and levonamtradol. 

Kathmann M, Haug K, Heils A, Noth en M, Schlicker E (2000) Exchange of three amino acids in the cannabinoid CBI receptor (CNRl) of an epilepsy patient 2000 Symposium on the Cannabinoids. International Cannabinoid Research Society, Burlington, Vermont... 

A confusing picture emerges when cannabinoids are evaluated in animal models of epilepsy (Karler and Turkanis 1981 Consroe and Snider 1986). CBD has anticonvulsant properties with a spectrum distinct from standard anticonvulsants, apparently not hampered by the development of tolerance but with a varying profile according to the species tested. THC can produce seizures in some circumstances but is anticonvulsant in others. In a recent study, THC (10 mg/kg) completely abolished spontaneous seizures in the rat pilocarpine model of epilepsy (Wallace et al. 2003). The results also indicated that endogenous cannabinoid tone may modulate seizure termination and duration via the CBi receptor. 

Wallace MJ, Blair RE, Falenski KW, et al (2003) The endogenous cannabinoid system regulates seizure frequency and duration in a model of temporal lobe epilepsy. J Pharmacol Exp Ther 307 129-137... 

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