Effects of an intravenous infusion of diltiazem on glomerular filtration rate, electrolyte excretion, and urine output in healthy dogs

BACKGROUND: Acute kidney injury (AKI) in dogs has a high case fatality rate. Diltiazem might improve renal function, but effect of intravenous infusion has not been adequately studied in dogs. HYPOTHESIS/OBJECTIVES: To determine if an intravenous infusion of diltiazem improves renal function through changes in glomerular filtration rate (GFR), fractional excretion of sodium (FENa), and urine output (UOP) in healthy dogs. ANIMALS: Ten healthy adult dogs. METHODS: Prospective, unmasked, crossover study. Dogs were randomized to receive diltiazem (loading dose of 240 μg/kg followed by 6 μg/kg/min for 300 min) or the same volume of 5% dextrose in water (D5W). The opposite treatment was given after a 7‐day washout period. GFR and FENa were obtained at baseline and after infusion. UOP was measured starting 1 hour before diltiazem administration. RESULTS: GFR did not significantly increase from baseline with diltiazem (before diltiazem median = 2.371 mL/min/kg, range = 1.605‐4.359; after diltiazem median = 2.305 mL/min/kg, range = 1.629‐4.387; median difference = 0.080 mL/min/kg, 95% confidence interval [CI] = −0.417 to 0.757; P = .85), and there was no difference in D5W GFR before and after diltiazem (median = 2.389 mL/min/kg, range = 1.600‐3.557; median difference = 0.036 mL/min/kg, 95% CI = −0.241 to 1.112; P = .69). FENa did not increase from baseline after administration of diltiazem (median difference = 0%, 95% CI = −0.1 to 0.1; P = .81), and there was no difference in D5W FENa (median difference = 0.1%, 95% CI = −0.1 to 0.2; P = .26). UOP did not increase with diltiazem (P = .06). CONCLUSION AND CLINICAL IMPORTANCE: Intravenous administration of diltiazem does not improve markers of renal function in healthy dogs. Further studies are needed in dogs with AKI.