These drugs are used in experimental trials and their effects analyzed. Drug trials are of two main types - open-label and blinded. In open-label studies both the researcher and the subject know what drug is being administered and why.

This type of study helps researchers decide whether there is a possibility that the drug might be useful. But further testing is needed, since it is not possible in an open-label trial to know whether there was a true drug effect or whether it was a placebo effect, which is common with psychoactive drugs. A placebo effect is a positive response based on a psychological reaction rather than on the workings of the drug. To rule out a placebo response and to make sure that the findings in an open trial are not just coincidence, a more rigorous blinded study is done, which involves concealing the identity of the drug from the subject or the researcher or both. The purpose of the drug is known, but some of the subjects are intentionally given another drug or a placebo as a basis of comparison.

Only after the study is completed does the researcher know who received the drug in question and who did not.

Opiate receptor blockers have shown promise in the treatment of alcoholism and addiction to opiates. These medications, which have been used for many years in emergency rooms to treat overdoses, literally push the drug off the receptor and reverse its effects. Naltrexone has been shown to reduce the frequency of relapse in opiate addicts and has been commercially available for several years. What is intriguing, however, is that studies have shown a similar benefit in alcoholics, and the use of naltrexone in the treatment of alcoholism is now well accepted in clinical practice. A related drug called nalmefene also shows promise in reducing relapse rates in alcoholics. Nalmefene differs from naltrexone in that it targets more than one opioid receptor.

Drugs that block the cravings associated with cocaine use are being actively sought; a number that are currently available have shown promise in open trials in reducing such cravings. Among these are the antidepressants imipramine and fluoxetine and the mood stabilizers carbamezepine and valproate. Studies in which a blinded methodology was used have not, however, consistently supported their effectiveness.

A drug that works consistently to reduce cravings will provide a breakthrough in the treatment of addiction.

Elizabeth Connell Henderson, M.D.

Glossary

Appendix A: Regulation of Addictive Substances

Appendix B: Sources of Additional Information