Lack of effect of withdrawal from cigarette smoking on theophylline pharmacokinetics.

The intravenous disposition of theophylline was determined in 12 healthy young male smokers during periods of smoking and short-term withdrawal (24 to 36 hours), using a crossover design. Median half-life, clearance, volume of distribution, hepatic extraction, and intrinsic clearance of theophylline during withdrawal were within +/- 5% of the corresponding median control (smoking) parameters and were normal in comparison with values published for smokers. The lack of change in the pharmacokinetic profile of theophylline indicates that adjustment of the dosage regimen should not be necessary immediately after smoking withdrawal.

The effect of acute withdrawal from cigarette smoking on indocyanine green and antipyrine clearance.

The effects of acute withdrawal from cigarette smoking on indocyanine green (ICG) clearance and antipyrine pharmacokinetics were studied in healthy young male volunteers. Two separate crossover clinical trials, each using 12 subjects, were used to compare the disposition of the drugs from 24 to 36 hours after withdrawal to the disposition found under control conditions. The median difference of ICG clearance and all antipyrine pharmacokinetic parameters from smoking control was less than 13%, indicating that short-term smoking withdrawal had no effect large enough to be of clinical significance on hepatic blood flow or hepatic drug-metabolizing capacity. Rates of hepatic blood flow were normal in comparison with values published for larger sample populations. The lack of any clinically significant effect of smoking withdrawal on hepatic blood flow or on the disposition of antipyrine, a drug with very low hepatic extraction, indicates that on a pharmacokinetic basis, changes in dosage regimens for most drugs are not necessary on acute withdrawal from smoking.