The Ocular and Systemic Adverse Effects of Topical 0.1% Diclofenac in Healthy Cats

Abstract

The objectives of this study were to characterize the ocular and systemic adverse effects, and systemic pharmacokinetics of topical 0.1% diclofenac. This was investigated in 8 healthy cats using a blinded, randomized, placebo-controlled, cross-over design. Drops were administered bilaterally 4 times daily for 7 days. Ocular, hepatic and renal variables were measured at various timepoints. Pharmacokinetic sampling occurred on Days 1 and 7. Treated animals were 8 times more likely to develop conjunctival hyperemia than control animals (p=0.0161). Pharmacokinetic analysis showed that accumulation occurs with repeated dosing. Topical 0.1% diclofenac treatment did not have any significant effect on hepatic or renal function, other than reduction GFR in the second phase of the study (p=0.0013). In conclusion, topical 0.1% diclofenac appears to be safe in healthy cats causing only mild ocular irritation. Careful patient selection may be indicated as systemically-absorbed diclofenac may be associated with reduction in GFR in volume-contracted states.