Abstract
Purpose:
With the arrival of new formulation in eye drops, some excipients were shown in vivo and ex vivo as irritant as the macrogolglycerol hydroxystearate 40 (MGH40) when used at a concentration of 5%. In order to assess the accuracy of these models, we perform a long term study in rabbits with high level of MGH40.
Methods:
Twenty-eight (28) male and female New Zealand White albino rabbits were involved in this study and assigned to two groups of 14 animals (7 male and 7 female) corresponding to the 3-month and 6-month time-points. A formulation containing 10% MGH 40 was instilled in the right eye, three times daily. The left eyes served as control. Ocular signs were evaluated daily over a 4 -week period and once a week for the following time using the slit lamp and indirect ophthalmoscopy. Intraocular pressure data were collected up to 6 months. Eye globes were collected and examined by histology at 3 months and 6 months.
Results:
After 3 times a day instillations during 6 months, the formulation was well tolerated. No ocular damage or clinically abnormal signs were observed in the cornea, conjunctiva or iris. Furthermore, corneal sensitivity and intraocular pressure values in the eyes of the treated eyes were similar to those in the non treated eyes.<br /> Histological examination revealed that neither the structure nor the integrity of the cornea or other ocular structures was affected.<br /> From a general point of view, there were no treatment-related effects on body weight, body weight gain, food and water consumption, clinical observations and the levels of hematology and biochemistry parameters were good. No treatment-related effects were observed at necropsy and there were no adverse effects related to the test item as assessed by histopathology.
Conclusions:
A formulation with MGH40 10% 3 times a day was well tolerated and the ocular surface remained normal after 6-month exposure. Thus, results obtained in vitro/ex vivo with the new prostaglandin preservative free formulation containing 5% MGH40 seem to be not predictive of in vivo tolerance.