Establishing population distribution of drug‐metabolizing enzyme activities for the use of salivary caffeine as a dynamic liver function marker in a Singaporean Chinese population

ABSTRACT Salivary paraxanthine/caffeine molar ratio has been proposed as a novel dynamic liver function test to guide dose adjustments of drugs hepatically‐cleared by CYP1A2. Its usability requires an established population norm as well as the factors influencing the ratio and actual concentrations. To address this knowledge gap, we measured salivary caffeine and paraxanthine concentrations at 4 h post caffeine dose in healthy Chinese individuals who have undergone 24 h of caffeine abstinence. Metabolic ratio was calculated and statistical analysis was performed. From the 52 participants (26 males; 30 regular caffeine consumers) recruited, salivary paraxanthine/caffeine molar ratio was normally distributed with mean and SD of 0.5 ± 0.2. No statistically significant factors (BMI, body weight, sex, and regularity of caffeine intake) affecting the metabolic ratio were found. Caffeine concentration and total caffeine plus paraxanthine concentrations were lower in males than females, and lower in regular caffeine consumers than non‐regular caffeine consumers. The 4‐h salivary metabolic ratio (mean: 0.5) was generally not significantly different from literature reported salivary, serum and plasma ratios measured at 4 – 9 h in healthy individuals (mean ranges from 0.4 to 0.7) but was significantly higher than literature reported 6‐h plasma ratio and salivary ratios measured at 1 – 6 h in patients with liver disease or mild abnormal liver function tests (mean...
Source: Biopharmaceutics and Drug Disposition - Category: Drugs & Pharmacology Authors: Tags: Original Paper Source Type: research