January 23, 2013
Researchers at the Michael E. DeBakey VA Medical Center have discovered that a common high blood pressure medication may also be effective in treating cocaine dependence.
The study found that rapid titration of the drug, doxazosin, significantly reduced cocaine use compared with slow titration of the drug or placebo. This research is important in supporting the increasingly widespread theory that the body’s noradrenergic system is an important pharmacologic target in the treatment of addiction.
"For so long, we believed that dopamine must be the primary target if we hoped to reduce drug craving and use; however, it has become clear that addressing other neurobiological systems is necessary if we hope to more effectively treat addiction," said Lead Investigator Daryl Shorter, M.D., a staff physician in the Mental Health Care Line and also an assistant professor of Psychiatry Research at Baylor College of Medicine.
The study included 35 cocaine-dependent participants who were randomly assigned to receive either doxazosin or a placebo for 17 weeks. The patients were first titrated at one milligram per day, with the dose increased by one milligram per week. When it was discovered that a change in dosing strategy could be safely tolerated by participants, a second study group was created in which a faster titration was employed. All participants in the study also received weekly cognitive behavioral therapy.
"We were surprised the slow titration group did not demonstrate a statistically significant difference from placebo, since we presumed the medication would at least have some effect, even if it was not as robust as in the fast titration group," said Shorter. "There is an argument for rapid titration of medications since you increase the serum concentration levels and can create a more robust effect more quickly, so it's possible this sort of phenomenon is the underlying reason behind the success in the fast titration group."
Although other potential pharmaceutical treatments for cocaine dependence have been explored by researchers worldwide, none have yet to offer a truly effective solution.
"Interestingly, stimulant dependence is like the final frontier in medication development for addictions treatment," said Shorter. “Currently, there are no FDA-approved medications for treatment of cocaine dependence or methamphetamine dependence, so the hunt is on for medications that will more effectively treat this illness."
VA researchers, in collaboration with colleagues at Baylor College of Medicine, are currently conducting a larger clinical trial of doxazosin in cocaine-dependent individuals, aiming for a target of 100 participants. Funding for the study was provided to co-author Thomas R. Kosten, M.D., by National Institutes of Health/National Institute on Drug Abuse grant # P50-DA12762.
As the largest research program embedded in an integrated health care system in the United States, and possibly the world, VA conducts cooperative research studies across a continuum – from biomedical and rehabilitation research to clinical trials, health services research, and quality improvement and implementation research.