Microparticles ocular delivery

To enhance encapsulation efficiency, a spray-drying method could be proposed. Thus, this technique provides a significant improvement of betamethasone encapsulation efficacy into PLGA microparticles, namely, 90% encapsulation efficacy compared with 15% for Wi/o/ W2 double emulsion process [28]. An emulsification/spray-drying technique has also been proposed as an alternative to the double emulsion method for encapsulation of peptide drug, vancomycin into microspheres for the topical ocular delivery (encapsulation efficacy 84-99%) [29]. 

With the aim of developing a drug delivery vehicle, hydrosilylated and thermally oxidized porous silicon microparticles were injected into the vitreous of rabbit eyes (Cheng et al. 2008). It was noted that the particles settled into the inferior vitreous cavity over a few days. Degradation of the hydrosilylated particles took considerable time (>4 months) in comparison to untreated particles which degraded within a period of 3 weeks. No adverse effects were observed in ocular tissues including the retina and the lens. Furthermore, normal ocular pressure was maintained. 

Laaksonen T, Santos H, Vihola H, Salonen J, Riikonen J, Heikkila T, Peltonen L, Kumar N, Murzin D, Lehto V, Hirvonen J (2007) Failure of MTT as a toxicity testing agent for mesoporous silicon microparticles. Chem Res Toxicol 20(12) 1913-1918 Low SP (2008) Development of porous silicon as a scaffold for the delivery of cells into ocular tissue. Flinders University, Department of Chemistry Low SP, Williams KA, Canham LT, Voelcker NH (2006) Evaluation of mammahan cell adhesion on surface modified porous silicon. Biomaterials 27 4538-4546 Masters J (2000) Animal cell culture a practical approach. OUP, Oxford... 

Addo RT, et al. Formulation, characterization and testing of tetracaine hydrochloride-loaded albumin-chitosan microparticles for ocular drug delivery. J Microencapsul 2010 27(2) 95-104. 

AddoRT, et al. Formulation and characterization of atropine sulfate in albumin-chitosan microparticles for in vivo ocular drug delivery. J Pharm Sci 2015 104(5) 1677—90. 

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