Thursday, April 25, 2013

Cocaethylene: Not Your Old Coca-Cola

We all know that the effects produced from the toxic ingestion of cocaine and alcohol as separate entities are excessive stimulation and pronounced depression, respectively. So what are the effects of the toxic ingestion of both compounds together?


Enter cocaethylene...and it is far from the Coca-Cola produced during your great grandmother's time.

Cocaethylene (also known as ethylbenzoylecgonine) is produced from the concomitant ingestion of cocaine and alcohol. It is formed by the liver through a transesterification reaction of cocaine that occurs in the presence of ethanol through the activity of the nonspecific enzyme, cocaine carboxylesterase.

Like cocaine, cocaethylene blocks the reuptake of dopamine in the central nervous system and increases the extracellular concentration of dopamine in the accumbens nucleus, which produces euphoria and other similar effects. This effect may potentiate the toxicity of cocaine. However, cocaethylene has very little activity on the serotonergic system. In addition, the half-life of cocaethylene is longer than that of cocaine (nearly 2 hours for cocaethylene, compared to 40 minutes for cocaine), which can lead to prolonged toxicity. In addition, the LD50 of cocaethylene is lower than that of cocaine, which can be of potential concern in the patient who presents with concomitant ingestion of cocaine and alcohol.

The order of ingestion is important here, as the ingestion of ethanol preceding the ingestion of cocaine will not only lead to the formation of cocaethylene, but will also increase the plasma levels of cocaine and lead to a prolonged euphoric effect.

In terms of manifestations of toxicity, animal models have demonstrated that cocaethylene has myocardial depression effects and can decrease stroke volume, contractility, and mean arterial pressure. In addition, it has also been shown to increase the incidence of EKG abnormalities and lead to life-threatening dysrhythmias in a dose-dependent manner as a result of its greater potent effects on sodium channel blockade. It has also been shown to have inhibitory properties on the potassium and calcium channels in the heart, and one case report has described a patient who experienced QTc prolongation and Torsades de Pointes as a result of a dual ingestion of cocaine and ethanol.

It is difficult to extrapolate the effects that cocaethylene has demonstrated in animal studies to human patients, but it is important to be mindful of the effects of the combination of cocaine and alcohol and the potential for the formation of cocaethylene in the setting of such a dual ingestion.

References:
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Wilson LD, Henning RJ, Suttheimer C, et al. Cocaethylene causes dose-dependent reductions in cardiac function in anesthetized dogs. J Cardiovasc Pharm 1995;26:965-973. [PMID: 8606535]
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Xu YQ, Crumb WJ, Clarkson CW. Cocaethylene, a metabolite of cocaine and ethanol, is a potent blocker of cardiac sodium channels. J Pharmacol Exp Ther 1994; 271:319-325. [PMID: 7965731]