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Comparison of the phenacetin and aminopyrine breath tests: Effect of liver disease, inducers and cobaltous chloride
Author(s) -
Schoeller Dale A.,
Kotake Alvin N.,
Lambert George H.,
Krager Patricia S.,
Baker Alfred L.
Publication year - 1985
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.1840050221
Subject(s) - phenacetin , chemistry , breath test , pharmacology , medicine , helicobacter pylori
The phenacetin breath test (PBT) has been proposed as an alternative to the aminopyrine breath test (ABT) for the assessment of hepatic function. To investigate the clinical utility of the PBT, we compared the PBT with the ABT in 9 healthy subjects and 18 patients with biopsy‐proven liver disease. We also investigated the effects of cytochrome P‐450 inducers in humans and rats, and the effect of cobaltous chloride (CoCl 2 ) in rats on the PBT to elucidate the relationship between the rate of phenacetin deethylation and exhaled labeled CO 2 derived from phenacetin. In humans with abnormal ABTs, the PBT correlated with the ABT (r = 0.77), but in healthy humans there was no correlation between the two breath tests. Rifampin pretreatment in healthy humans induced the ABT by 27%, but did not induce the PBT. In rats the PBT was not induced by 3‐methylcholanthrene pretreatment at phenacetin doses of 1 mg per kg, but was induced by both 3‐methylcholanthrene (178%) and phenobarbital (142%) at 10 mg per kg phenacetin. Pretreatment of rats with CoCl 2 , which reduces cytochrome P‐450 content, decreased the PBT by 40% and the ABT by 84%. The insensitivity of the PBT to induction except at high doses of phenacetin suggests that phenacetin deethylation is not the rate‐limiting process modulating exhaled labeled CO 2 in healthy subjects, and that the PBT does not generally reflect normal or induced phenacetin dealkylation rates. The PBT, however, did reflect hepatic damage and may even be better than the ABT for grading the severity of hepatic damage.