The pharmacokinetics and metabolism of idazoxan in the rat
| Autor: | K. Waltham, C. J. Lewis, N. C. Muir, J. G. Lloyd-Jones, M. A. McCleavy, M. E. Havler, M. J. Humphrey |
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| Rok vydání: | 1988 |
| Předmět: |
Male
endocrine system medicine.medical_specialty Health Toxicology and Mutagenesis Urine Pharmacology Dioxins Toxicology Biochemistry Dioxanes Excretion Pharmacokinetics Idazoxan Oral administration Internal medicine medicine Animals Distribution (pharmacology) Tissue Distribution heterocyclic compounds Adrenergic alpha-Antagonists Biotransformation Chromatography High Pressure Liquid Chemistry Hydrolysis Rats Inbred Strains General Medicine Metabolism Rats Bioavailability Endocrinology nervous system Enzyme Induction Female Chromatography Thin Layer medicine.drug |
| Zdroj: | Xenobiotica. 18:519-532 |
| ISSN: | 1366-5928 0049-8254 |
| Popis: | 1. [2'-14C]Idazoxan was rapidly and completely absorbed after its oral administration to rats. 2. After administration of either [2'-14C] or [6,7-3H]idazoxan, radioactivity was taken up by a wide range of tissues and became localized, especially in the organs of metabolism and excretion. Quantitative distribution patterns were route-dependent such that oral dosing resulted in lower radioactivity concentrations in all tissues apart from liver. 3. Clearance of idazoxan (94-144 ml/min per kg) was due mostly to metabolism and was independent of dose. Oral bioavailability in male rats at low oral doses of idazoxan (10 mg/kg) was about 1%, but increased with increasing dose to 23% at 100 mg/kg. Oral bioavailability in female rats was considerably higher than in male rats, at all doses studied. Brain idazoxan levels were in equilibrium with those in plasma, but ten-fold higher. 4. Elimination of radioactivity after administration of 14C-idazoxan was via the urine and the faeces (about 75% and 20% of dose respectively) and occurred essentially in the 24 h period immediately after dosing. By 96 h after dosing, elimination was virtually complete, with less than 0.5% dose remaining in the carcasses. 5. Biotransformation was by hydroxylation at positions 6 and 7 to form phenolic metabolites, which were excreted as glucuronide and sulphate metabolites in urine, but unconjugated in faeces. Other minor metabolic routes were 5-hydroxylation or oxidative degradation of the imidazoline ring, but these pathways were of quantitatively minor importance in the rat. |
| Databáze: | OpenAIRE |
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