Sensitivity and tolerance to nicotine in smokers and nonsmokers.

We studied the responses of smokers and lifelong non-smokers to transdermal nicotine patches over 24 h in three groups of subjects: non-smokers on a 15 mg patch (n = 8), non-smokers on a 30 mg patch (n = 8) and smokers on a 30 mg patch (n = 8). Unexpectedly, the non-smokers appeared to absorb nicotine more rapidly. The increase in blood nicotine concentrations of non-smokers over the first 2 h of patch use was double that of the smokers, with mean increases of 4.5 (SD = 3.7), 10.9 (SD = 4.2) and 4.1 (SD = 2.7) ng/ml in the three groups, respectively (P less than 0.005). The smokers had no pleasant or unpleasant effects from the 30 mg patch (X Cmax 13.9 ng/ml, SD = 4.9; Tmax 8.75 h) but all eight non-smokers experienced mild nausea and lightheadedness (P less than 0.01) within the first hour, and seven dropped out (P less than 0.01) at 3-8 h due mainly to severe nausea, vomiting or headache (X Cmax 18.4 ng/ml, SD = 4.9; Tmax 5.25 h). Only one non-smoker dropped out on the 15 mg patch, but five had transient nausea in the first hour (X Cmax 7.9 ng/ml, SD = 3.0; Tmax 8.0). Our study provides evidence of chronic pharmacodynamic nicotine tolerance in smokers, but does not address whether this is acquired or innate. The higher rate of transdermal nicotine absorption in non-smokers is unexplained and requires replication.