Effects of telmisartan on renal excretory function in conscious dogs

The present study investigated the effects of telmisartan, a selective AT, receptor antagonist, on renal function in dogs. Conscious female dogs were treated with (i) vehicle (controls) and three doses of telmisartan (0.03 mg /kg, 0.1 mg/kg and 0.3 mg/kg) administered intravenously; (ii) vehicle and three doses of telmisartan (0.3 mg/kg, 1.0 mg/kg and 3.0 mg/kg) administere d orally; or (iii) 1.0 mg/kg per day telmisartan orally for 12 days. Eight dogs were used for each experiment. Each of the four treatments in (i) and (ii) was administered 7 days apart. During the 6 h after intravenous admini stration, urine volume was significantly higher in dogs treated with telmis artan 0.1 mg/kg (8.5 +/- 1.6 ml/kg) and 0.3 mg/kg (7.0 +/- 0.9 ml/kg) than controls (2.7 +/- 0.3 ml/kg; P < 0.05), and renal sodium excretion was incr eased significantly with telmisartan 0.03 mg/kg (803 +/- 124 mu mol/kg), 0. 1 mg/kg (1039 +/- 213 mu mol/kg) and 0.3 mg/kg (966 +/- 161 mu mol/kg) vers us controls (159 +/- 21 mu mol/kg; P < 0.05). Oral telmisartan at doses of 1.0 mg/kg and 3.0 mg/kg also produced significant increases in urine volume (7.2 +/- 1.1 ml/kg and 6.6 +/- 1.2 ml/kg, respectively) and renal sodium e xcretion (599 +/- 146 mu mol/kg and 555 +/- 131 mu mol/kg, respectively) co mpared with controls (2.8 +/- 0.5 ml/kg and 80 +/- 33 mu mol/kg; P < 0.05) over the 6-h postdose period. Telmisartan at all intravenous doses and at 3 .0 mg/kg orally increased the urinary excretion of chloride significantly o ver the 6-h post-dose period compared with vehicle alone. The excretion of potassium and creatinine were unchanged by any treatment. Telmisartan 1.0 m g/kg administered orally for 12 days produced similar results. In conclusio n, acute intravenous or oral as well as subchronic oral administration of t elmisartan to conscious dogs promotes diuresis and natriuresis without affe cting potassium or creatinine excretion.