Transdermal nicotine substitution: pharmacokinetics of nicotine and cotinine.

The use of tobacco has resulted in major health related problems worldwide. Nicotine replacement is one of the most promising strategies in smoking cessation. The in vivo delivery rate and the pharmacokinetic properties of a recently developed transdermal nicotine system (TNS) was investigated in three separate studies. Two sizes (16 cm2 and 24 cm2) of the patches were tested. Mean daily nicotine delivery, expressed by a first order kinetic, varied between 0.9 and 1.0 mg/cm2 patch. The different sizes of the patches led to linearly dose-related nicotine plasma Cmax- and AUC-values. The nicotine levels achieved were in the same range with those of other nicotine patches and the chewing gum. As a result of multiple dose kinetic, no significant accumulation of nicotine was observed. Mean elimination half-life of nicotine after removal of the patches (3.5 +/- 1.8 h for the larger patch and 4.5 +/- 1.9 h for the smaller patch) was longer than reported values after i.v. administration, which was reported to vary between 40 and 120 min.

Lack of a pharmacokinetic interaction between carvedilol and digitoxin or phenprocoumon.

The possibility of a pharmacokinetic interaction between carvedilol and digitoxin (Study I) or phenprocoumon (Study II) has been evaluated in groups of 12 healthy volunteers. The bioavailability (Cmax, tmax, AUC) of digitoxin and phenprocoumon were assessed after a single dose, given once alone and once on day 6 of treatment with carvedilol 25 mg o.d. Cmax, tmax, AUC and Ut of carvedilol and desmethylcarvedilol were also investigated after the fifth dose of carvedilol and after the sixth dose given concomitantly with digitoxin or phenprocoumon. In Study I, the 95% confidence intervals of the ratio test versus the reference findings were; digitoxin Cmax 0.80-1.20, tmax 0.56-1.14, AUC 0.97-1.33, and for carvedilol Cmax 0.81-1.22; tmax 0.66-1.23; AUC 0.91-1.17. Formation of the active metabolite desmethylcarvedilol and the urinary recovery of carvedilol and desmethylcarvedilol were not influenced by digitoxin. In Study II Cmax and AUC of phenprocoumon were not changed after carvedilol. Cmax of carvedilol was decreased after phenprocoumon. The kinetic parameters of phenprocoumon were Cmax 0.80-1.05, tmax 0.47-2.00, AUC 0.78-1.05, and for carvedilol Cmax 0.59-1.06, tmax 0.71-1.73; AUC 0.80-1.08, respectively. The plasma levels of desmethylcarvedilol and the urinary recovery of carvedilol and desmethylcarvedilol were not influenced by phenprocoumon. The blood pressure and heart rate after carvedilol alone were not affected by concomitant administration of digitoxin or phenprocoumon.

Pharmacokinetics of nicotine and cotinine after application of two different nicotine patches under steady state conditions.

Tobacco use has resulted in major health related problems world-wide. Transdermal nicotine replacement therapy is one of the most promising strategies in smoking cessation. In the present trial the pharmacokinetic properties of two matrix patches (A and B) were characterized and compared after daily application on day 4. Predose nicotine concentrations on day 4 with patch B were higher than with patch A (12.7 +/- 9.5 ng/ml vs. 8.3 +/- 5.3 ng/ml). With patch A there was a steeper increase up to the peak level, followed by a decline gradually up to 24 h. 24 h after application predose levels were reached again, demonstrating absence of significant accumulation of nicotine. The calculated elimination half-lives of nicotine (3.4 +/- 1.8 h after patch A and 3.3 +/- 2.0 h after patch B) were longer than after i.v. application (published values range from 40 to 120 min). Under steady state cotinine concentrations remained constant.

Pharmacokinetics of nicotine after application of a 30 cm2 nicotine patch under steady-state conditions.

Transdermal nicotine systems (Nicotinell 30) were applied daily to the skin of healthy nicotine-dependent smokers for 4 days. Blood samples were taken for the measurement of nicotine and cotinine in plasma using capillary gas chromatography with nitrogen detection. The plasma concentration-time profiles of nicotine and cotinine and the pharmacokinetic parameters cmax, tmax, AUC and the elimination half-life were determined under steady-state conditions. Nicotine levels after application of the 30 cm2 patch were in accord with published values for 10, 20 and 2 x 20 cm2 patches. The elimination half-life of nicotine after removal of the patch was longer than reported values obtained after i.v. application.