A population and familial study of the defective alicyclic hydroxylation of debrisoquine among Egyptians.

1. Debrisoquine hydroxylation exhibited profound variation in 72 Egyptian volunteers. 2. The frequency distribution histogram of the metabolic ratio (ratio unchanged drug: 4-hydroxy metabolite in 0-8 h urine) was polymodal. 3. From family data it was possible to define more clearly than before the heterozygous characteristics. 4. Egyptians appear in general to be more extensive oxidizers of debrisoquine than do English subjects. 5. Ramadan fasting was found to lower the absorption of debrisoquine.