Paper
Thursday, July 12, 2007
Smoking Cessation: Potentially Risky Impact on Prescribed Medications
Susan D. Schaffer, PhD, FNP, BC, Department of Family, Women's & Children's Nursing, University of Florida College of Nursing, Gainesville, FL, USA and Saunjoo L. Yoon, RN, PhD, College of Nursing, University of Florida, Gainesville, FL, USA.
| Learning Objective #1: Describe the effects of smoking cessation on the metabolism of prescribed drugs. |
| Learning Objective #2: Describe alterations in dosing of prescribed drugs that should be considered in patients who stop smoking. |
One Healthy People 2010 goal is to decrease smoking prevalence from 24 percent to 12 percent. Primary care providers are urged to assess all patients for tobacco use, to strongly recommend tobacco cessation, and to prescribe nicotine replacement or buproprion to help patients quit (Fiore, Baily & Cohen et al., 2000). However, it is not well recognized that the metabolism of many prescribed drugs is accelerated by tobacco smoking, and that smoking cessation may increase blood levels of some drugs by as much as 40%. This effect occurs because polycyclic aromatic hydrocarbons in tobacco smoke induce cytochrome P450 (CYP) 1A1, CYP1A2, and possibly CYP2E1. This study presents results of a comprehensive search for drug-tobacco interactions using a web-based program (Clinical Pharmacology Drug Interactions, Gold Standard Multimedia, Tampa, Florida, 2005). Tobacco was entered as a search term, every interaction listed by the program was reviewed and those pertaining to smoking cessation were selected. This search was supplemented by a Medline Search using tobacco-drug interaction as search terms. The metabolism of drugs from 11 categories, including antihypertensive, anti-anxiety, opioid analgesics, antidepressant, anti-psychotic, anticoagulant, bronchodilator, anti-migraine, endocrine, antiarrhythmic, and dementia drugs were found to be affected and recommendations for altered dosing will be discussed in this presentation. Of these, smoking cessation has the most important clinical effects on coumadin and diabetes drugs due to narrow therapeutic ranges. These drug metabolism changes could be particularly important in older persons, whose drug metabolism is affected by aging and who are more likely to be taking multiple drugs. Although not a focus of this study, several days of abstinence from chronic tobacco smoking decreases caffeine clearance by roughly 40%. New tobacco abstainers should be advised to decrease their intake or caffeinated beverages to prevent an increased caffeine effect that may compromise the smoking cessation effort.