Activities of cytochrome P450 1A2, N-acetyltransferase 2, xanthine oxidase, and cytochrome P450 2D6 are unaltered in children with cystic fibrosis.

The activities of hepatic cytochrome P450 (CYP) 1A2, N-acetyltransferase 2 (NAT-2), xanthine oxidase (XO), and CYP2D6 were evaluated in 12 young children (aged 3-8 years) with mild cystic fibrosis (CF) and 12 age-matched healthy control subjects by use of standard caffeine and dextromethorphan phenotyping methods. Subjects were given 4 oz of Coca-Cola (approximately 35 mg caffeine) (The Coca-Cola Company, Atlanta, Ga) and a single 0.5-mg/kg dose of dextromethorphan.