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New hope for preventing strokes in cocaine addicts

Cocaine users place themselves at high risk of suffering strokes, even six months after using. Thankfully, a group of medications called dihydropyridine-class calcium channel antagonists show promise at stopping cocaine-induced strokes.

Addiction researchers at The University of Texas (UT) Health Science Center at San Antonio, the UT Houston Health Science Center and the UT Southwestern Medical Center at Dallas present these conclusions in the lead article of this month's American Journal of Psychiatry. The scientists, Bankole A. Johnson, M.D., Ph.D., and Nassima Ait-Daoud, M.D., of the UT Health Science Center at San Antonio, Michael D. Devous Sr., Ph.D., of UT Southwestern, and Pedro Ruiz, M.D., of UT Houston, reviewed 34 years of studies on the subject and examined them in light of today's neurochemical understandings.

The article highlights the researchers' own groundbreaking work on the development of isradipine, a calcium channel antagonist, as an effective weapon for treating cocaine-induced stroke. "We did the main work on isradipine and have reanalyzed those findings," said Dr. Johnson, the William and Marguerite S. Wurzbach Distinguished Professor at the Health Science Center. "More studies are needed of this medication."

Cocaine use increases levels of the neurochemical dopamine and results in reduced arterial blood flow to the brain. This obstruction of blood flow is known as cocaine-induced cerebral ischemia. Isradipine, which shows promise as a therapeutic agent for this form of ischemia, acts by restoring and maintaining blood flow to dopamine-rich brain regions.

"Taking cocaine causes brain damage," Dr. Johnson said. "This medication provides new hope for preventing and treating one of the major causes of death and disability in cocaine addicts."

Dr. Johnson is professor of psychiatry and pharmacology, deputy chairman for research in the department of psychiatry, and chief of the alcohol and drug addiction division. He directs the Southwest Texas Addiction Research & Technology Center (START), a comprehensive research site near the Health Science Center in San Antonio. He is one of the country's foremost researchers of addictive behavior, particularly in the areas of alcoholism and cocaine abuse. The START Center officially opened last May.

"The practical demonstration of the treatment for cocaine-induced strokes is ongoing at the START Center," Dr. Johnson said. "This continues five years of painstaking research to find effective medications with which to help addicts who are at high risk from suffering strokes. Clinical trials of isradipine are the next step, since we now have proof of concept that it works."

Users may place themselves at up to 14 times greater risk of cocaine-induced stroke. Researchers have observed a rising tide of strokes in addicts since the earliest verified cases in the late 1970s. According to a 1997 National Institute on Drug Abuse household survey, 1.5 million Americans were cocaine users. The Office of National Drug Control Policy estimates the number at 3.6 million when data on under-represented users are taken into account. Emergency room visits related to cocaine use are estimated to be in excess of 150,000 per year.

The researchers are optimistic that what they have learned will have important implications for the treatment of ischemic strokes due to other causes. Grants DA-13002-01 and DA-12191 from the National Institute on Drug Abuse funded their studies.
The American Journal of Psychiatry is the most widely circulated journal of psychiatry in the world. It is the official journal of the American Psychiatric Association.

Contact: Will Sansom, (210) 567-2570 Alternate: Aileen Salinas