PEG-MESOPOROUS SILICA FOR TOPICAL DELIVERY OF BRIMONIDINE TO THE EYE
Song Ah Ko1,2, Se Na Kim1, Seung Ho Lee1, Beom Kang Huh1, Young Bin Choy1,3
1Seoul National University, South Korea, South Korea;
2College of Medicine and Institute of Medical and Biological Engineering, Medical Research Center, Seoul National University, South Korea;
3Institute of Medical & Biological Engineering, Medical Research Center, Seoul National University, South
Eye drop formulation for glaucoma drug is limited in very short drug residence time at the preocular space, hence very low drug bioavailability. To resolve this, we proposed polyethylene glycol (PEG)-coated mesoporous silica as carriers for topical delivery of a glaucoma drug, brimonidine to the eye. The amine-functionalized mesoporous silica (AMS) was fabricated via anionic surfactant-mediated synthesis method (S-N+~I- mechanism), which were then coated with PEG (MW = 6000) to give the PEG-AMS. Thus, the pores in AMS would serve as drug reservoir for sustained delivery and the PEG would allow a mucoadhesive effect. After loading brimonidine, we evaluated the in vitro drug release profile in pH 7.4 PBS. After a burst release of 70 % for the first 20 min, the drug was slowly released for 8 h. In vivo
experiments were conducted by administrating the brimonidine-loaded PEG-AMS to the rabbit eye. As we measured the change in intraocular pressure (IOP), the period of lowered IOP was about 14 h after the administration of PEG-AMS and this was more than twice longer than that with a commercialized eyedrop medication of brimonidine, Alphagan P (6 h), indicating a greatly enhanced drug bioavailability with the PEGAMS herein.