Medication for Cocaine Addiction
Presently, there are no medications approved by the U.S. Food and Drug Administration to treat cocaine addiction, though researchers are exploring a variety of neurobiological targets.
Past research has primarily focused on dopamine, but scientists have also found that cocaine use induces changes in the brain related to other neurotransmitters—including serotonin, gamma-aminobutyric acid (GABA), norepinephrine, and glutamate. Researchers are currently testing medications that act at the dopamine D3 receptor, a subtype of dopamine receptor that is abundant in the emotion and reward centers of the brain. Other research is testing compounds that restore the balance between excitatory (glutamate) and inhibitory (GABA) neurotransmission, which is disrupted by long-term cocaine use.
Several medications marketed for other diseases show promise in reducing cocaine use within controlled clinical trials. Among these, disulfiram, which is used to treat alcoholism, has shown the most promise. Scientists do not yet know exactly how disulfiram reduces cocaine use, though its effects may be related to its ability to inhibit an enzyme that converts dopamine to norepinephrine. However, disulfiram does not work for everyone. Pharmacogenetic studies are revealing variants in the gene that encodes the DBH enzyme and seems to influence disulfiram’s effectiveness in reducing cocaine use. Knowing a patient’s DBH genotype could help predict whether disulfiram would be an effective pharmacotherapy for cocaine dependence in that person
Finally, researchers have developed and conducted early tests on a cocaine vaccine that could help reduce the risk of relapse. The vaccine stimulates the immune system to create cocaine-specific antibodies that bind to cocaine, preventing it from getting into the brain. In addition to showing the vaccine’s safety, a clinical trial found that patients who attained high antibody levels significantly reduced cocaine use. However, only 38 percent of the vaccinated subjects attained sufficient antibody levels and for only 2 months.
Researchers are working to improve the cocaine vaccine by enhancing the strength of binding to cocaine and its ability to elicit antibodies. New vaccine technologies, including gene transfer to boost the specificity and level of antibodies produced or enhance the metabolism of cocaine, may also improve the effectiveness of this treatment. A pharmacogenetics study with a small number of patients suggests that individuals with a particular genotype respond well to the cocaine vaccine—an intriguing finding that requires more research.
In addition to treatments for addiction, researchers are developing medical interventions to address the acute emergencies that result from cocaine overdose. One approach being explored is the use of genetically engineered human enzymes involved in the breakdown of cocaine, which would counter the behavioral and toxic effects of a cocaine overdose. Currently, researchers are testing and refining these enzymes in animal research, with the ultimate goal of moving to clinical trials.