Abstract
Purpose: :
The studies were designed to compare the ocular hypotensive effects, PK profiles, and ocular safety of the BAK-free latanoprost emulsion Catioprost® and the BAK-preserved latanoprost solution Xalatan® in cynomologus monkeys with glaucoma and rabbits, respectively.
Methods: :
For the efficacy evaluation, glaucomatous eyes (high IOP was induced by laser photocoagulation of the trabecular meshwork) were instilled once a day for 5 consecutive days. Each monkey (n=8) received both test drugs, in a cross-over design with at least a 2-week washout period. IOP was measured at baseline, and at treatment days 1, 3, and 5; before drug instillation, then hourly for 6 hours. Latanoprost acid free ocular concentrations (cornea, conjunctiva, ciliary body, and aqueous humor) following a single instillation in rabbits were determined at time points 0.25, 0.5, 1, 4, 6, and 24h. The local tolerance of bid instillations for both formulations was assessed over a 28- day period in the rabbit (n=6 per group).
Results: :
Both latanoprost formulations shared the same efficacy profile, and the IOP reduction lasted 24h. The maximum reduction in IOP occurred 2h after each morning dose and was 4.4±0.5 (-15%), 5.9±0.5 (-20%), and 7.8±0.8 mmHg (-26%) on treatment days 1, 3 and 5, respectively for Catioprost®. The same IOP reduction was observed for Xalatan®. This equivalence in efficacy was confirmed by the PK data. The comparison in AUCs demonstrated that the latanoprost-cationic emulsion was not significantly different from Xalatan®, 217 vs. 295 pg/mg.h in the ciliary body, respectively. While both formulations were well tolerated, the number of transient ocular reactions (conjunctiva redness) was reduced by 50% with the BAK-free Catioprost®. Neither ocular nor nasal mucosa histologic findings were noted for both formulations.
Conclusions: :
The BAK-free latanoprost-cationic emulsion (Catioprost®) appears to be as potent as Xalatan® with an improved safety profile. Thus, Catioprost® may be a safer alternative to deliver therapeutic doses of latanoprost for the long term treatment of glaucoma.
Keywords: intraocular pressure • drug toxicity/drug effects • trabecular meshwork