The influence of diclofenac ophthalmic solution on the intraocular pressure lowering effect of 0.005% latanoprost in glaucomatous patients

Purpose To verify the influence of a non-steroidal anti-inflammatory drug (NSAID) ophthalmic solution on the intraocular pressure (IOP) reduction induced by 0.005% latanoprost and 0.5% timolol eyedrops, in patients affected by primary open-angle glaucoma (POAG). Methods Randomized, prospective, masked clinical study. Thirty-two POAG adults, compensated with 0.5% timolol, were randomized into two study groups (A and B). Timolol was continued for two weeks in all patients. At the 3rd week, group A started a 5-week therapy with topical 0.1% diclofenac, whereas placebo were administered to group B. On the 15th day, in both groups timolol was replaced by latanoprost, and this regimen lasted for eight weeks. IOP was recorded at 7-day intervals during the first seven weeks and at the 10th week. Results NSAID and placebo did not modify the IOP-lowering effect induced by timolol. In both groups, latanoprost induced a significant IOP decrease. NSAID-treated patients exhibited a marked fall in IOP (p < 0.01) whereas, in placebo-treated patients, this diminution was less noticeable (p < 0.05). After NSAID withdrawal, in group A IOP significantly increased (p < 0.01), remaining approximately at the same level up to the end of the study. In group B there were no significant differences in IOP at the same checks. Conclusion In POAG patients, diclofenac significantly enhances the latanoprost-induced IOP-lowering effect, without affecting the timolol hypotensive efficacy. The synergism between NSAID and latanoprost could represent an advantage, but also an unconsidered risk of ocular hypotony, during the long-term treatment of glaucomatous patients.