title: Studies on the effects of omeprazole on thyroid function in the rat.
abstract: The effects of omeprazole (an H+, K+ -ATPase inhibitor) on thyroid parameters in rats have been examined. SK&F Wistar rats were dosed orally with omeprazole (up to 500 mg kg-1) or vehicle. Treatment for 7 or 14 days resulted in generally decreased plasma T3 concentrations in males (with little change or slight increases in females) and increased serum TSH concentrations (22%-68% increases). No changes were detected in thyroid 125I uptake or organification. Liver 5'-deiodinase activity was decreased in male rats after 7 days treatment. Thyroxine clearance was not altered after a single dose of omeprazole. In-vitro studies showed omeprazole to be only a weak inhibitor of TSH-stimulated 125I organification in cultured porcine thyrocytes. It is concluded that omeprazole has weak effects on the pituitary-thyroid-liver axis, its main action being to inhibit the peripheral deiodination of thyroid hormones.
authors.affiliation: Smith Kline & French Research Ltd, Welwyn, Herts, UK.
authors.forename: C K
authors.initials: CK
authors.lastname: Atterwill
authors.forename: C G
authors.initials: CG
authors.lastname: Brown
authors.forename: K L
authors.initials: KL
authors.lastname: Fowler
authors.forename: C A
authors.initials: CA
authors.lastname: Jones
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005260:Female; D066298:In Vitro Techniques; D007453:Iodide Peroxidase / Q000378:metabolism; D007455:Iodine / Q000378:metabolism; D007457:Iodine Radioisotopes; D008297:Male; D009853:Omeprazole / Q000494:pharmacology*; D010472:Perchlorates / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013552:Swine; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000187:drug effects*; D013963:Thyroid Hormones / Q000097:blood; D013974:Thyroxine / Q000378:metabolism
chemical_list: D007457:Iodine Radioisotopes; D010472:Perchlorates; D013963:Thyroid Hormones; D007455:Iodine; D007453:Iodide Peroxidase; D009853:Omeprazole; D013974:Thyroxine