1. Biliary excretion of technetium-99m-sestamibi in wild-type dogs and in dogs with intrinsic (ABCB1-1Δ mutation) and extrinsic (ketoconazole treated) P-glycoprotein deficiency
- Author
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Russell L. Tucker, G. Roberts, Katrina L. Mealey, D. K. Waiting, John S. Mattoon, and J. C. Coelho
- Subjects
Male ,Technetium Tc 99m Sestamibi ,medicine.medical_specialty ,ATP-binding cassette transporter ,Endogeny ,Pharmacology ,Excretion ,Dogs ,Polymorphism (computer science) ,Internal medicine ,medicine ,Animals ,Bile ,Drug Interactions ,Gamma Cameras ,ATP Binding Cassette Transporter, Subfamily B, Member 1 ,Adverse effect ,P-glycoprotein ,Polymorphism, Genetic ,General Veterinary ,biology ,Wild type ,Gallbladder ,Ketoconazole ,Endocrinology ,biology.protein ,Female ,medicine.drug - Abstract
P-glycoprotein (P-gp), the product of ABCB1 gene, is thought to play a role in the biliary excretion of a variety of drugs, but specific studies in dogs have not been performed. Because a number of endogenous (ABCB1 polymorphisms) and exogenous (pharmacological P-gp inhibition) factors can interfere with normal P-gp function, a better understanding of P-gp's role in biliary drug excretion is crucial in preventing adverse drug reactions and drug-drug interactions in dogs. The objectives of this study were to compare biliary excretion of technetium-99m-sestamibi ((99m)Tc-MIBI), a radio-labelled P-gp substrate, in wild-type dogs (ABCB1 wild/wild), and dogs with intrinsic and extrinsic deficiencies in P-gp function. Dogs with intrinsic P-gp deficiency included ABCB1 mut/mut dogs, and dogs with presumed intermediate P-gp phenotype (ABCB1 mut/wild). Dogs with extrinsic P-gp deficiency were considered to be ABCB1 wild/wild dogs treated with the P-gp inhibitor ketoconazole (5 mg/kg PO q12h x 9 doses). Results from this study indicate that ABCB1 mut/mut dogs have significantly decreased biliary excretion of (99m)Tc-MIBI compared with ABCB1 wild/wild dogs. Treatment with ketoconazole significantly decreased biliary excretion of (99m)Tc-MIBI in ABCB1 wild/wild dogs. P-gp appears to play an important role in the biliary excretion of (99m)Tc-MIBI in dogs. It is likely that concurrent administration of a P-gp inhibitor such as ketoconazole will decrease P-gp-mediated biliary excretion of other substrate drugs as well.
- Published
- 2009
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