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Title: Disposition of intravenous radioactive acyclovir

The kinetic and metabolic disposition of (8-14C)acyclovir (ACV) was investigated in five subjects with advanced malignancy. The drug was administered by 1-hr intravenous infusion at doses of 0.5 and 2.5 mg/kg. Plasma and blood radioactivity-time, and plasma concentration-time data were defined by a two-compartment open kinetic model. There was nearly equivalent distribution of radioactivity in blood and plasma. The overall mean plasma half-life and total body clearance +/- SD of ACV were 2.1 +/- 0.5 hr and 297 +/- 53 ml/min/1.73 m2. Binding of ACV to plasma proteins was 15.4 +/- 4.4%. Most of the radioactive dose excreted was recovered in the urine (71% to 99%) with less than 2% excretion in the feces and only trace amounts in the expired Co2. Analyses by reverse-phase high-performance liquid chromatography indicated that 9-(carboxymethoxymethyl)guanine was the only significant urinary metabolite of ACV, accounting for 8.5% to 14.1% of the dose. A minor metabolite (less than 0.2% of dose) had the retention time of 8-hydroxy-9-((2-hydroxyethoxy)methyl)guanine. Unchanged urinary ACV ranged from 62% to 91% of the dose. There was no indication of ACV cleavage to guanine. Renal clearance of ACV was approximately three times the corresponding creatinine clearances.
Authors:
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Publication Date:
OSTI Identifier:
5511035
Resource Type:
Journal Article
Resource Relation:
Journal Name: Clin. Pharmacol. Ther.; (United States); Journal Volume: 30:5
Research Org:
Wellcome Research Laboratories, Research Triangle Park, NC
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; 62 RADIOLOGY AND NUCLEAR MEDICINE; CARBON 14 COMPOUNDS; RADIONUCLIDE KINETICS; RADIOPHARMACEUTICALS; CLEARANCE; BIOLOGICAL LOCALIZATION; CARBON DIOXIDE; FECES; METABOLISM; METABOLITES; PATIENTS; RADIATION DOSES; URINE; BIOLOGICAL MATERIALS; BIOLOGICAL WASTES; BODY FLUIDS; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; DOSES; DRUGS; LABELLED COMPOUNDS; MATERIALS; OXIDES; OXYGEN COMPOUNDS; WASTES 560171* -- Radiation Effects-- Nuclide Kinetics & Toxicology-- Man-- (-1987); 550601 -- Medicine-- Unsealed Radionuclides in Diagnostics