The research has supported acute changes in metabolic rate associated with changes in smoking, but chronic changes have not been as well supported. A further hypothesis for the weight change seen with change in smoking habits is the speculation that cigarette smoke or nicotine changes the weight set point of the smoker (reviewed in Perkins, 1993).

Investigators have found that weight changes upon smoking initiation and cessation are nicotine associated (Emont and Cummings, 1987; Grunberg et al., 1986). Consistent with many previous studies, Doherty et al. (1996) found that nicotine replacement during smoking cessation suppresses weight gain. In their randomized control study, they describe a linear relationship between nicotine dose and postcessation weight gain, with placebo users gaining the most weight. This relationship was maintained when smoking was biochemically validated by serum cotinine.

DRUG INTERACTIONS

Exposure to cigarette smoke affects the metabolism of many categories of drugs, which may make the action of a certain dose of a drug unpredictable. Certain constituents of tobacco smoke can affect drug action through pharmacokinetic (changes in absorption, distribution, metabolism, and elimination) and pharmacodynamic (changes in drug action or response) actions (Schein, 1995). Among the best-understood agents that affect enzymes of drug metabolism are polycyclic aromatic hydrocarbons (PAHs) and nicotine—though less defined—selectively induces various cytochrome P-450 (CYP) enzymes and uridine 5-diphosphate (UDP) glucuronosyltransferases, while carbon monoxide and heavy-metal constituents have been found to inhibit or decrease certain CYP enzymes (Zevin and Benowitz, 1999).

The effect of cigarette smoke exposure on drug metabolism can influence the action of many commonly used drugs, including certain antidepressants, antipsychotics, heart medications such as β-blockers and antiarrhythmics, anticoagulants, alcohol, caffeine, theophylline, and others (D’Arcy, 1984; Schein, 1995; Zevin and Benowitz, 1999). Many of the drug interactions are of unknown clinical significance, but others may necessitate the adjustment of medication dose among smokers.

Although not considered to be due to an interaction of cigarette smoke and oral contraceptive pills, it is important to note the significantly increased risk of cardiovascular and cerebrovascular events in female smokers using oral contraceptives.

FIRE SAFETY

Cigarettes are the leading cause of accidental fires in the United States, causing about 20–25% of all fire deaths and resulting in about 1,000 deaths



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