Abstract
Proprietary formulations of sulfaphenazole were administered intravenously and orally to sheep. After intravenous injection the disposition of sulfaphenazole was described by an open two compartment model, and the elimination half-time was on average 5.58 h. The apparent volume of distribution was 0.273 1/kg and total body clearance 34.1 ml/kg/h. Judged from the area under the curves, the oral dose was completely absorbed, Drug plasma concentrations versus time fitted an open one compartment model, the half-time of absorption and elimination being 2.66 and 7.12 h, respectively. The binding to plasma proteins was high i.e. 93–96 % at therapeutic concentrations, and concentration dependent. The results demonstrate that the doses indicated by the manufacturer appear to be low and more appropriate for drugs with a longer elimination half-time. Consequently, considerable adjustments in the dosage regimen are recommended.
Sammendrag
Registrerte formuleringer av sulfafenazol (Eftolon®) ble gitt intravenøst og oralt til sau. Etter intravenøs injeksjon kunne konsentrasjonene av sulfonamid i plasma tilpasses en to-kompartment modell. Halveringstiden for eliminasjonen var i gjennomsnitt 5,58 t, tilsynelatende distribusjonsvolum 0,273 l/kg, og total clearance 34,1 ml/kg/t. Bedømt etter arealet under kurvene, ble sulfafenazol fullstendig absorbert etter oral dosering. Konsenstrasjoner i plasma ble beskrevet av en en-kompartmenit modell med halveringstider for absorpsjon og eliminasjon på henholdsvis 2,66 og 7,12 t. Binding til plasmaproteiner var konsentrasjonsavhengig, og varierte ved terapeutiske konsentrasjoner av sulfafenazol fra 93 til 96 %.
Resultatene viser at de doser som angis av produsenten er lave, foruten at doseintervallene passer bedre for farmaka med lengre halveringstid. Det er følgelig anbefalt vesentlige endringer i doseringsregime.
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Ødegaard, S.A. Pharmacokinetics of Sulfaphenazole in Sheep. Acta Vet Scand 27, 243–249 (1986). https://doi.org/10.1186/BF03548168
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DOI: https://doi.org/10.1186/BF03548168