Developments in Brief : Smoking and Prescription Drugs Do Not Mix, an Expert Declares

People who take prescription medication and also smoke cigarettes now have one more reason to stop lighting up: Smoking cigarettes can interfere with how the body metabolizes drugs.

The result, according to John F. Schlegel, president of the American Pharmaceutical Assn., is that smokers may need to take greater amounts of drugs or to take them more frequently to get the same effect as nonsmokers.

Among the drugs that smoking interferes with are anti-anxiety drugs, including diazepam (commonly sold as Valium); painkillers such as propoxyphene (sold as Darvon); tricyclic antidepressants, including amitriptyline (sold as Elavil, Amitril and others); anti-blood-clotting drugs, such as heparin; phenothiazines including chlorpromazine (sold as Thorazine); anti-asthmatic drugs, including theophylline, and the anti-angina drugs known as beta blockers (propranolol).