title: Critical appraisal of 13C breath tests for microsomal liver function: aminopyrine revisited.
abstract: As liver diseases are a major health problem and especially the incidence of metabolic liver diseases like non-alcoholic fatty liver disease (NAFLD) is rising, the demand for non-invasive tests is growing to replace liver biopsy. Non-invasive tests such as carbon-labelled breath tests can provide a valuable contribution to the evaluation of metabolic liver function. This review aims to critically appraise the value of the (13) C-labelled microsomal breath tests for the evaluation of metabolic liver function, and to discuss the role of cytochrome P450 enzymes in the metabolism of the different probe drugs, especially of aminopyrine. Although a number of different probe drugs have been used in breath tests, the perfect drug to assess the functional metabolic capacity of the liver has not been found. Data suggest that both the (13) C(2) -aminopyrine and the (13) C-methacetin breath test can play a role in assessing the capacity of the microsomal liver function and may be useful in the follow-up of patients with chronic liver diseases. Furthermore, CYP2C19 seems to be an important enzyme in the N-demethylation of aminopyrine, and polymorphisms in this gene may influence breath test values, which should be kept in mind when performing the (13) C(2) -aminopyrine breath test in clinical practice.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Kirsten E
authors.initials: KE
authors.lastname: Pijls
authors.forename: Hanne
authors.initials: H
authors.lastname: de Vries
authors.forename: Suzan
authors.initials: S
authors.lastname: Nikkessen
authors.forename: Aalt
authors.initials: A
authors.lastname: Bast
authors.forename: Will K W H
authors.initials: WK
authors.lastname: Wodzig
authors.forename: Ger H
authors.initials: GH
authors.lastname: Koek
mesh_terms: D000081:Acetamides / Q000378:metabolism; D000632:Aminopyrine / Q000737:chemistry / Q000378:metabolism*; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D001944:Breath Tests / Q000379:methods*; D002110:Caffeine; D002247:Carbon Isotopes / Q000032:analysis*; D065731:Cytochrome P-450 CYP2C19; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D006801:Humans; D007553:Isotope Labeling; D008107:Liver Diseases / Q000175:diagnosis* / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism*; D015394:Molecular Structure
chemical_list: D000081:Acetamides; D002247:Carbon Isotopes; D000632:Aminopyrine; C035495:methacetin; D002110:Caffeine; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19
keywords: aminopyrine; breath tests; caffeine; cytochrome P450 enzymes; genetic polymorphisms; liver function; methacetin; microsomal; phenacetin