Tanning Capacity and Nicotine Dependence Among African Americans

Darker skin color is associated with a lower likelihood of smoking cessation among males but not females

Darker skin color is associated with discrimination and unfair treatment and may contribute to persisting health disparities. This study examined whether darker skin color was associated with smoking cessation and whether this association was moderated by sex and race. This study also explored whether biological and psychosocial factors, including nicotine and cotinine concentrations, discrimination, distrust, and neuroticism, mediated this association. The data for this study came from a prospective smoking cessation intervention that included 224 Black and 225 White adults from Kansas City, Missouri. Skin color was assessed using a DermaSpectrometer to measure melanin contained within the skin. Point prevalence smoking abstinence was biochemically-verified and assessed at weeks 4 and 26. Hierarchical logistic regression analyses were conducted to evaluate hypothesized relations between skin color and smoking cessation. Interactions between race and sex with skin color were also evaluated. While skin color was not associated with smoking cessation in the overall sample or among Blacks only, results indicated that sex moderated the effect of skin color on smoking cessation after adjusting for race and other covariates. Among males, darker skin color was associated with lower odds of achieving smoking abstinence at weeks 4 (OR = 0.60 [95% CI = 0.36, 0.99]) and 26 (OR = 0.52 [95% CI = 0.29, 0.91]). Skin color did not predict smoking cessation among females. Skin color was positively correlated with discrimination (r = 0.15, p = 0.02), cynicism/distrust (r = 0.14, p = 0.03) and neuroticism (r = 0.24, p < 0.01) among males only. However, these factors did not mediate the association between skin color and smoking cessation. Skin color may contribute to cessation-related health disparities among Black males, but more research is needed to understand the psychosocial and biological mechanisms through which skin color influences tobacco cessation.

Relationship between skin melanin index and nicotine pharmacokinetics in African American smokers

BACKGROUND

Blacks bear a disproportionate burden of smoking-related diseases and experience greater difficulty quitting smoking than Whites. Nicotine has a high affinity for melanin, and it has been hypothesized that melanin levels might influence nicotine pharmacokinetics and enhance dependence. The aim of this study was to evaluate the hypothesis that melanin affects nicotine disposition kinetics in humans.

METHODS

Forty-four Black participants were administered intravenous infusions of deuterium-labeled nicotine and cotinine. Plasma concentrations of nicotine and cotinine were measured, and pharmacokinetic parameters were estimated. The constitutive and facultative melanin indexes were measured using a dermaspectrophotometer.

RESULTS

The median constitutive melanin index was 60.7 (32.8-134.7) and the median facultative melanin index 68.1 (38.6-127.1). The mean (±SD) nicotine elimination half-life was 136 min (±33.5), clearance was 1237 mL/min (±331), and Vss was 204 L (±66), or 2.6 L/kg (±0.7). No evidence of significant differences was found in nicotine pharmacokinetic parameters by comparing participants in different melanin index quartiles (outliers with very high melanin index had similar pharmacokinetic values to others). Differences were not statistically significant when adjusted for age, BMI, sex and CYP2A6 genotype or the nicotine metabolite ratio (NMR), and no evidence of significant correlations were found between melanin (facultative or constitutive) and the pharmacokinetic parameters of nicotine or cotinine or tobacco dependence measures.

CONCLUSIONS

Based on our finding in this group of Black smokers, we could not confirm the hypothesis that melanin significantly affects nicotine disposition kinetics or measures of tobacco dependence.