Table 2.

Sum of urinary nicotine and nicotine metabolites (cotinine, COT; trans-3’-hydroxycotinine, 3HC; $\sum \text{NIC+COT+3HC}$) and the 3HC/COT ratio (marker of CYP2A6 activity) as time sensitive markers of overall tobacco exposure and metabolism in mice.

Product	0–1h Post-Exposure	1–2h Post-Exposure	2–3h Post-Exposure	3–16h Post-Exposure	0–3h Post-Exposure
e-cig CT: ∑	11.02±0.53	4.86±0.78	2.61±0.60	0.58±0.38	18.48±1.32*
e-cig MM: ∑	14.12±0.78	5.98±1.84	6.08±1.16	0.36±0.18	26.18±2.49*
MCS: ∑	66.06±6.76	47.52±8.86	36.27±4.88	3.13±0.51	--
e-cig CT: 3HC/COT	7.40±0.80	11.13±3.05	12.65±6.17	15.59±6.97	9.71±1.44
e-cig MM: 3HC/COT	8.78±0.41	11.63±4.15	13.98±3.81	NA	11.26±1.40
MCS: 3HC/COT	4.27±0.48	6.47±0.98	17.69±5.01	10.15±2.46	8.89±1.85

Abbr: e-cig CT, Classic Tobacco; e-cig MM, Magnificent Menthol; MCS, mainstream cigarette smoke of KY Reference cigarette, 3R4F; --, not calculated; NA, not applicable due to zero denominator). Values = means±SE in ng/mg creatinine (for $\sum \text{NIC+COT+3HC}$ data only); n=4–5 for all products at all time points (except for product ratios at 3–16h post-exposure where n=1, 0, and 4 for CT, MM, and MCS, respectively). *P<0.05 between e-cig CT and e-cig MM by t-test.