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Plasma Pharmacokinetics of Topical 0.1% Diclofenac Sodium and 0.5% Ketorolac Tromethamine in Dogs

Year: 2025

Type: article

Abstract: ABSTRACT Objective To determine plasma concentrations of ophthalmic 0.1% (w/v) diclofenac sodium and 0.5% (w/v) ketorolac tromethamine following 4 times daily ophthalmic administration in healthy dogs. Animals Studied Eight healthy research Beagles. Procedures A prospective, masked, randomized, crossover study was conducted. Eight dogs were randomly assigned to a diclofenac or ketorolac group (4 dogs per group). Plasma was collected before drug administration (time 0/baseline). Each dog received 0.05 mL, equivalent to one drop of diclofenac or ketorolac into both eyes 4 times daily for 5 days (4 am, 8 am, 12 pm, and 4 pm). Plasma samples were collected at 5, 15, 30, 60, 120, 240, and 360 min after the 4 pm treatment on Days 1 and 5. Plasma concentrations (ng/mL) were quantified by liquid chromatography‐mass spectrometry and analyzed with noncompartmental pharmacokinetic analysis. A Wilcoxon signed rank test was used to determine statistical significance ( p < 0.05). Results After ophthalmic administration of 0.1% diclofenac, mean t 1/2 , T max , and C max occurred at 3.08 ± 0.9 h, 121.4 ± 2.8 h, 0.12 ± 0.05 μg/mL, respectively. The mean t 1/2 , T max , and C max after 0.5% ketorolac administration were 18.5 ± 14.6 h, 121.6 ± 2.0 h, 1.8 ± 1.7 μg/mL, respectively. The AUC 0‐∞ for diclofenac and ketorolac was 8.97 ± 3.73 μg/mL*h and 98.2 ± 43.3 μg/mL*h, respectively. Conclusions Diclofenac and ketorolac were rapidly absorbed systemically after ophthalmic administration. The half‐life of topical ketorolac is six times longer than that of diclofenac.

Source: Veterinary Ophthalmology

DOI: 10.1111/vop.70105