Characteristics of Volunteers and Plasma Concentration of Nicotine and Cotinine
| Plasma concentration (ng/mL) | |||||
|---|---|---|---|---|---|
| Group | Age (y ± SD) | Packs/d | Pack years | Nicotine | Cotinine |
| Nonsmokers | 24 ± 6 | — | — | ND | ND |
| Smokers | |||||
| 4-h withdrawal | 28 ± 4 | 0.8 ± 0.3 | 6.1 ± 4.3 | 7.6, 8.9* | 282 ± 189 |
| 10-d withdrawal | 27 ± 6 | 0.8 ± 0.2 | 6.3 ± 3.9 | ND | ND |
| 21-d withdrawal | 28 ± 3 | 0.8 ± 0.3 | 6.3 ± 4.5 | ND | ND |
↵* Results from only 2 subjects (3 other subjects had nondetectable values).
Packs/d = number of packs smoked per day; Pack years = number of packs per day while smoking multiplied by number of years smoked; ND = not detected (detection limits for nicotine and cotinine were 5.0 and 100 ng/mL, respectively).
Values are expressed in mean ± SD.