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Further information
Pharmacokinetic particulars
In dogs, after a single intravenous dose at 0.1 mg/kg, the total body clearance was 0.017 L/h∙kg, the volume of distribution was 0.14 L/kg and the terminal half-life was 7.0 hours. After a single oral dose of 0.1 mg/kg, the oral absolute bioavailability corresponded to about 90%. The oral absorption was fast with mean Tmax at 0.93 hours after administration of 0.1 mg/kg. The maximum plasma concentrations Cmax corresponded to 1.1 µg/mL after a single oral dose of 0.1 mg/kg and to 19 µg/mL after a single oral dose of 1.6 mg/kg. The AUCinf corresponded to 6.3 µg∙h/mL after a single oral dose of 0.1mg/kg and to 153.6 µg∙h/mL after a single oral dose of 1.6 mg/kg. The plasma protein binding was > 98%. A large proportion of the dose (between 61% and 70%) is excreted in the urine as unchanged parent drug. Two metabolites (a dealkylated and a hydroxylated metabolite) were also identified in urine. The parent drug is metabolised by the hepatic cytochrome P450 families 3A4 and 2E1, and to a lesser extent by 2C9. Dose proportionality for Cmax and AUCinf was demonstrated between 0.2 and 1.6 mg/kg. Feeding significantly increased torasemide AUClast by 36% on average and slightly delayed Tmax but no significant impact on Cmax was detected. After repeated administration to dogs at 0.2 mg/kg daily for 14 days, no plasma accumulation of torasemide was detected.