Influence of low-dose oral contraceptives, alcohol, and grapefruit on [C-13]aminopyrine breath test

The aminopryine breath test (ABT) measures hepatic reserve in patients with acute and chronic liver disease and gives an assesment of the hepatic func tion in patients undergoing major liver surgery. Aminopyrine is metabolized by the mixed cytochrome P-450 system, which can be influenced by many fore ign compounds and drugs. Whether these foreign compounds and drugs can infl uence the results of the ABT has seldomly been tested. We studied three gro ups: Healthy female volunteers, either normally menstruating or taking oral contraceptives, were asked to perform a [C-13]ABT during the time of the m enses and at midcylce. Healthy volunteers were asked to perform a ABT after consuming 30 g of alcohol. Healthy volunteers were asked to perform a ABT after consuming 250 ml of grapefruit juice. The C-13/C-12 ratio in expired air was measured by gas isotope ratio mass spectrometry.