Vitamin A palmitate and aciclovir biodegradable microspheres for intraocular sustained release
ABSTRACT The aim of this study was to obtain a prolonged release of Vitamin A palmitate (RAP) and aciclovir from biodegradable microspheres for intraocular administration with an antiviral action and to be capable of preventing the inherent risks of intravitreal administration. The RAP effect on the microsphere characteristics was also studied. Poly(D,L-lactic-co-glycolic) acid microspheres were prepared by the solvent evaporation method. Different quantities of aciclovir (40-80 mg) and RAP (10-80 mg) were added to the internal phase of the emulsion. Microspheres were analysed by scanning electron microscopy, which revealed a spherical surface and a porous structure, and granulometric analysis that showed an adequate particle size for intraocular administration. The aciclovir loading efficiency increased when Vitamin A palmitate was added. Differential scanning calorimetry detected no differences in the polymer glass transition temperature and the aciclovir melting endotherm in all formulations. The release of aciclovir during the first days of the in vitro assay was improved with respect to microspheres without RAP. The microspheres showed a constant release of aciclovir and RAP for 49 days. Best results were obtained for microspheres prepared with 40 mg aciclovir, 80 mg RAP and 400mg polymer. A dose of 4.74 mg of microspheres would be therapeutic for the herpes simplex and Epstein-Barr viruses' treatment in an animal model and would reduce the intravitreal adverse effects. The injectability of a suspension of microspheres in isotonic saline solution resulted appropriate for its injection through a 27 G needle.
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ABSTRACT: This chapter discusses various types of dispersed systems, including applications of coarse and colloidal dispersions as pharmaceutical dosage and delivery systems. Applications of colloidal dispersions as controlled drug delivery systems are also discussed in this chapter.
- Journal of Drug Delivery Science and Technology 12/2008; 18(2):119-124. DOI:10.1016/S1773-2247(08)50019-0 · 1.09 Impact Factor
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ABSTRACT: The incorporation of additives such as polyoxyethylated oleic acid glycerides (PEG-derivative) can modify the release of drugs from microparticles. PEG-derivative decreases the release rate of drugs that are dissolved in PLGA matrices but if un-dissolved the initial release rate slightly increases. To clarify this behaviour the influence of adding PEG-derivative in the preparation of microspheres was investigated by scanning electron microscopy, differential scanning calorimetry, gel permeation chromatography, nuclear magnetic resonance and infrared spectroscopy. Cytotoxicity of this resulting PLGA/PEG-derivative matrix was evaluated in cell lines (fibroblasts) which are more reproducible but less specific and in primary cell cultures (splenocytes and human leucocytes) which have the advantage of their specificity. Scanning electron microscopy revealed that PLGA/PEG-derivative microspheres exhibited small surface concavities with a highly porous polymeric matrix. The incorporation of PEG-derivative caused a slight reduction in the T(g) values of PLGA. In vitro degradation studies showed that PEG-derivative remains within the microspheres as long as the matrix does. This PLGA/PEG-derivative matrix was well tolerated exhibiting cell viabilities similar to PLGA microspheres and can be used to modulate the release of drugs from microparticulate systems destined for parenteral administration.International Journal of Pharmaceutics 04/2008; 352(1-2):50-7. DOI:10.1016/j.ijpharm.2007.10.007 · 3.79 Impact Factor