Effect of tepoxalin on renal function and hepatic enzymes in dogs exposed to hypotension with isoflurane

Objective: To evaluate the possible renal and hepatic toxicity of tepoxalin in dogs exposed to hypotension during isoflurane anesthesia.

Study design: Prospective, randomized experimental study.

Animals: Twenty adult mixed-breed dogs, weighing 18.8 ± 2.8 kg.

Methods: The animals received 10 mg kg(-1) tepoxalin orally 2 hours before the anesthetic procedure (PRE; n = 6), or 30 minutes after anesthesia (POST; n = 6), along with a control group (CON; n = 8), which were only anesthetized. The PRE and POST groups also received the same dose of tepoxalin for 5 days post-procedure. All dogs were anesthetized with propofol and maintained with isoflurane and the end-tidal isoflurane (Fe'Iso) was increased until mean arterial pressure decreased to 50-60 mmHg. These pressures were maintained for 60 minutes. Heart rate, arterial pressures and Fe'Iso were recorded at 0, 10 and every 10 minutes up to 60 minutes of hypotension. Blood gases, pH, electrolytes and bleeding time were analyzed before and at 30 and 60 minutes of hypotension. Renal and hepatic changes were quantified by serum and urinary biochemistry and creatinine clearance.

Results: Serum concentrations of alanine amino transferase (ALT), alkaline phosphatase (ALP) and γ-glutamyl transferase (GGT), blood urea nitrogen (BUN) and creatinine (Cr), and urinary output, urinary Cr, Cr clearance, and GGT:Cr ratio remained stable throughout the evaluations. During the anesthetic procedure there were no important variations in the physiological parameters. No side effects were observed in any of the groups.

Conclusions and clinical relevance: Tepoxalin did not cause significant effects on renal function or cause hepatic injury in healthy dogs exposed to hypotension with isoflurane, when administered pre- or postanesthetic and continued for five consecutive days.