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

Abstract 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.