Wednesday, October 3, 2001

Scientists Find New Approach To Developing Medications To Prevent Relapse To Cocaine Use

ScienceDaily (Oct. 3, 2001) — Research teams from the Drug Abuse Program of the VU Medical Center in the Netherlands and the intramural laboratories of the National Institute on Drug Abuse (NIDA) have identified a process in the brain that may lead to a new generation of medications to prevent relapse to cocaine use.

In studies using rats, the scientists, led by Dr. Taco J. De Vries of VU Medical Center and Dr. Yavin Shaham of NIDA, found that the same system–the cannabinoid system–that governs the pharmacological actions of marijuana in the brain also plays an important role in the neuronal processes underlying relapse to cocaine use.

By blocking cannabinoid receptor activity with chemical antagonists, the investigators prevented relapse to cocaine use induced by exposure to cocaine-associated cues or by cocaine itself.

Click here to read entire article at Science

Thursday, July 12, 2001

Researchers Find That After Stopping Cocaine Use, Drug Craving Gets Stronger Over Time

ScienceDaily (July 12, 2001)

Using an animal model of drug craving in laboratory rats, researchers at the Intramural Research Program of the National Institute on Drug Abuse (NIDA) have found that craving for cocaine seems to increase, rather than decrease, in the days and months after drug use has stopped.

"This phenomenon helps explain why addiction is a chronic, relapsing disease," says NIDA Director Dr. Alan I. Leshner. "Craving is a powerful force for cocaine addicts to resist, and the finding that it persists long after last drug use must be considered in tailoring treatment programs."

The research team, which included Drs. Jeff Grimm, Bruce Hope, Roy Wise and Yavin Shaham, published its findings in the July 12, 2001, issue of Nature.

In the study, the scientists found that sensitivity to drug-associated environmental cues that often accompany drug craving and relapse increased over a 60-day withdrawal period. Cocaine craving was inferred from the behavior of rats trained to press a lever to receive intravenous cocaine injections. Once the animals had learned to associate the lever-pressing with receiving cocaine, they were tested under conditions where they could continue to press the lever, but no longer received cocaine.

In humans, drug-associated environmental cues often stimulate cocaine craving and accompany relapse to drug-using behavior. The NIDA investigators wrote in their report to Nature that "the data from this study suggest that an individual is most vulnerable to relapse to cocaine use well beyond the acute drug withdrawal phase."

Adapted from materials provided by NIH/National Institute On Drug Abuse.

Tuesday, May 15, 2001

New Discovery Offers Hope Of Better Treatments For Cocaine Addiction Relapse

ScienceDaily (May 15, 2001)

Researchers at the Albert Einstein College of Medicine have identified a key mechanism involved in relapse to cocaine addiction. In determining the involvement of the neurotransmitter glutamate in relapse in the rat, the Einstein researchers also suggest a promising target for developing effective treatments for preventing relapses. They report their findings in the May 11 issue of Science.

"We stimulated a region of the brain that contains the neurotransmitter glutamate and were able to cause relapse," explains Dr. Stanislav R. Vorel, first author of the study that he and his Einstein colleagues conducted in conjunction with Dr. Eliot Gardner of the National Institute on Drug Abuse, a unit of the U.S. National Institutes of Health.

The study explored the effects of electrical stimulation of the hippocampus region of the brain, which is one of the regions associated with memory.

"We found that electrical stimulation of the hippocampus, a memory area that may underlie the memory of drug effects, led to drug-seeking behavior," says Dr. Vorel, who is a graduate student at the Albert Einstein College of Medicine. Dr. Vorel previously received his M.D. degree in the Netherlands.

Further, the researchers were able to demonstrate that a glutamate blocker (kynurenic acid) blocks relapse, suggesting to them that glutamate blockers could be good ingredients for developing new addiction treatments.

"Previous drug development has focused on the neurotransmitter dopamine, which is connected to the 'liking' region of the brain, rather than the 'wanting' response we observed in the hippocampus," says Dr. Vorel. "Since 'wanting' a drug is more directly connected to relapse - which is the greatest hindrance to successful addiction treatment - we believe glutamate could prove a promising target for new drug developments designed to treat cocaine addiction."

Adapted from materials provided by Albert Einstein College Of Medicine.

Thursday, March 29, 2001

Relapsed Smokers Can Be Successfully Re-Treated

ScienceDaily (Mar. 29, 2001)

PORTLAND, Ore. – In one of the first "recycling" studies to examine people who attempt to quit smoking after first failing medical treatment, researchers at Oregon Health Sciences University and their colleagues found abstinence rates five times greater for participants taking bupropion compared to participants taking a placebo. Study results are being presented at 12 p.m. on Saturday, March 24, at the Society for Research on Nicotine and Tobacco Annual Meeting in Seattle.

"Patients often feel discouraged following treatment with medications such as bupropion or nicotine patches if they are unable to successfully quit smoking," said David Gonzales, Ph.D., director of the OHSU Smoking Cessation Center and lead author of the study results. "However, evidence-based options for patients in this situation have been few. This is the first study to show that smokers can be retreated with bupropion successfully."

Bupropion, marketed in sustained release form as Zyban, is a nicotine-free prescription medication designed to reduce nicotine cravings and other symptoms normally associated with nicotine withdrawal. The multicenter study involved 450 adult cigarette smokers who averaged 15 cigarettes per day prior to the study, and who had been unable to quit or had relapsed after a previous course of bupropion. Study participants were randomly selected to receive bupropion SR or a placebo.

Typically, people who attempt to quit smoking on their own experience 5 percent to 7 percent success rates, while smokers who try bupropion a first time generally enjoy a better-than-30 percent long-term success rate. In this study, smokers re-treated with the drug had a 27 percent abstinence rate after seven weeks, compared to 5 percent abstinence for the placebo group. At 12 weeks, 20 percent of smokers being re-treated were still smoke free compared to three percent of the subjects in the placebo group.

Zyban is marketed by GlaxoSmithKline Pharmaceuticals.

Adapted from materials provided by Oregon Health Sciences University.