Long-term tolerance of preservative-free eye drops containing macrogol hydroxystearate as an excipient

Summary Purpose This in vivo animal study was conducted to assess the tolerability of macrogloglycerol hydrostearate 40 (MGH 40), commonly used as a solubilizing excipient in prostaglandin F 2α analogue eye drops without benzalkonium chloride. Methods Twenty-eight (14 males and 14 females) New Zealand white albino rabbits in good health and with no signs of ocular irritation were randomly assigned to receive 25 μL instillations of a solution containing 10% MGH 40 in the right eye 3 times daily for either 3 or 6 months. Ocular examinations of the conjunctiva, cornea and iris (using an ophthalmoscope and slit-lamp), corneal sensitivity, and intraocular pressure were assessed in both the right (treated) and left (untreated) eyes throughout the study. General characteristics, hematology and serum biochemistry parameters were also assessed throughout the study and necropsy examinations were performed at study completion. Results There were no treatment-related effects on the cornea, conjunctiva, iris, or intraocular pressure. Transient findings were generally seen in the untreated as well as the treated eye. Similarly, there were no treatment-related findings in either the hematology or serum biochemistry data or at necropsy. There were no differences based on gender. Conclusions Long-term administration of a 10% MGH 40-containing formulation three times per day in a standard in vivo animal model was well tolerated and had no ocular or other effect.