Chlorothiazide absorption in humans--possible example of Michaelis-Menten kinetics

Chlorothiazide absorption was studied in five healthy adult males at 1,000, 750, 500 and 250-mg dose levels. The 24-hour-absorbed fraction fell from a mean value of 20.15% of the orally administered dose at the 250-mg level to 8.38% at 1,000 mg. Analysis of data at the four dosage levels for each subject is suggestive of the fact that chlorothiazide absorption is possibly an example of Michaelis-Menten kinetics. Possible factors responsible for the saturable absorption are discussed.