Table 1. Unadjusted Mean Levels of Plasma Nicotine by Nicotine Form, Concentration, and Flavor at 4 Time Points.

Variable	Plasma nicotine level, mean (95% CI), ng/mL
Variable	0 min	5 min	10 min	35 min
Nicotine form
Salt	2.0 (1.6-2.4)	8.4 (7.3-9.5)^a	8.5 (7.3-9.6)^a	12.3 (10.7-14)^a
Freebase	2.0 (1.4-2.5)	4.3 (3.7-4.9)^a	4.9 (4.3-5.5)^a	7.0 (6.1-7.9)^a
Nicotine concentration, %
1	2.0 (1.4-2.5)	4.9 (4.3-5.5)^a	4.9 (4.4-5.5)^a	6.7 (5.9-7.4)^a
5	2.0 (1.5-2.4)	7.8 (6.7-9.0)^a	8.5 (7.3-9.6)^a	12.6 (10.9-14.3)^a
Flavor
Menthol	1.9 (1.3-2.4)	6.6 (5.5-7.7)	7.1 (6.0-8.1)	10.2 (8.7-11.6)^a
Tobacco	2.1 (1.7-2.5)	6.1 (5.4-6.9)	6.3 (5.5-7.1)	9.1 (7.8-10.4)^a

^{^a}

Significant difference between the 2 conditions of nicotine form, concentration, and flavor in generalized linear mixed models.