[Effects of pilocarpine in new ophthalmic formulations on intraocular pressure in rabbits with ocular hypertension].
OBJECTIVE
To assess the effects of pilocarpine (PC) incorporated into an in situ gelling vehicle, submicron emulsion vehicle, polyvinyl alcohol vehicle and PC solution on intraocular pressure (IOP) in rabbits with carbomer-induced elevation of IOP.


METHODS
Forty-three rabbit eyes with carbomer-induced elevation of IOP were randomly divided into 5 groups. Each eye in every group received topical application of PC from one of the ophthalmic formulations. IOP was measured before and 1, 2, 3, 4, 5, 7, 10, 12, 22 and 24 hours (h) after topical ocular administration of the ophthalmic formulations.


RESULTS
The reduction in IOP lasted for 7 h and the maximum decrease was (12.25 +/- 5.28) mm Hg in the hypertensive eyes treated by 2% PC solution. The reduction in IOP lasted for 12 h and the maximum decrease was (13.67 +/- 4.61) mm Hg in the hypertensive eyes treated by 2% PC gel. The reduction in IOP lasted for 24 h and the maximum decrease was (13.63 +/- 3.58) mm Hg in the hypertensive eyes treated by 4% PC gel. The reduction in IOP lasted for 12 h and the maximum decrease was (13.55 +/- 3.90) mm Hg in the hypertensive eyes treated by 2% PC submicron emulsion. The reduction in IOP lasted for 10 h and the maximum decrease was (10.89 +/- 4.04) mm Hg in the hypertensive eyes treated by 2% PC polyvinyl alcohol. The duration of action for lowering IOP lasted longer following administration with new ophthalmic formulations as compared to 2% PC solution. The series of prolongation is as follows: 4% PC gel > 2% PC gel = 2% PC submicron emulsion > 2% PC polyvinyl alcohol > 2% PC solution. The maximum reduction in IOP was not significantly different among the groups. No clinical evidence of ocular toxicity occurred in all groups except mild conjunctival injection.


CONCLUSIONS
These results indicate that the duration of action for lowering IOP is longer in PC gel, PC submicron emulsion and PC polyvinyl alcohol as compared to PC solution. The duration of action with 4% PC gel lasts the longest among all the groups. A single dose of 4% PC gel applied once daily can reduce IOP for 24 h.
Xu
Yan
Y
Henan Institute of Ophthalmology, Zhengzhou 450003, China. xuyan990301@yahoo.com.cn
Chen
Zuji
Z
Song
Jiezhen
J
D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D005260:Female; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D009798:Ocular Hypertension / Q000188:drug therapy*; D009883:Ophthalmic Solutions; D010862:Pilocarpine / Q000008:administration & dosage* / Q000627:therapeutic use; D011817:Rabbits; D011897:Random Allocation
D000959:Antihypertensive Agents; D009883:Ophthalmic Solutions; D010862:Pilocarpine