Effects of novel hybrids of caffeic acid phenethyl ester and NSAIDs on experimental ocular inflammation

In this study, we report the design and synthesis of novel hybrids of caffeic acid phenetyl ester (CAPE) and non-steroidal anti-inflammatory drugs (NSAIDs). We assessed their effects on an experimental ocular inflammation in New Zealand rabbits. The formulations of CAPE–aspirin and CAPE–indomethacin hybrids were topical instilled in the rabbit׳s eye. Afterwards, the anti-inflammatory activity was evaluated by grading the clinical signs and by assessing the inflammatory cell count, protein, PGE2 and TNFα levels in the aqueous humor. Furthermore, ocular tolerability of hybrids formulations was evaluated in a separate set of animals by using a modified Draize test. The ocular inflammation in the control group was significantly higher than in both the hybrid-treated groups, as indicated by clinical grading and biomarkers assessment. However, only the CAPE–aspirin hybrid reduced, in a significant dose-dependent manner, the ocular inflammation elicited by paracentesis. CAPE–indomethacin hybrid was able to significantly attenuate the clinical grading and the PGE2 aqueous levels only at the highest dose (0.1%). CAPE–aspirin significantly reduced PGE2 and TNFα levels in the aqueous humor as well as proteins and PMNs. Finally, all formulations showed no ocular irritation compared with vehicle-treated group. In conclusion, CAPE–aspirin shows full anti-inflammatory efficacy in experimental model of ocular inflammation demonstrating an optimal pharmacological and safety profile. Taken together these data indicate that CAPE–aspirin hybrid represents a valid and safe new chemical entity potentially useful for the treatment of ocular inflammation.