Genta I, Conti B, Perugini P, Pavanetto F, Spadaro A, Puglisi G
Department of Pharmaceutical Chemistry, University of Pavia, Italy.
J Pharm Pharmacol. 1997 Aug;49(8):737-42. doi: 10.1111/j.2042-7158.1997.tb06103.x.
The bioavailability of acyclovir to the ophthalmic epithelium is low and when the drug is administered in ophthalmic ointment it must be applied every four hours. An emulsification technique has been used to prepare acyclovir-loaded chitosan microspheres with the aim of promoting the prolonged release of drug and increasing its ocular bioavailability. The microparticulate drug-delivery systems obtained have been characterized for their morphology and physicochemical characteristics by in-vitro dissolution tests and in-vivo ocular administration to rabbits. The results show that the microspheres obtained are always quite small--the diameters of 90% of the particles are < or = 25 microns (i.e. d 90% never exceeds 25 microns) and physicochemical characterization shows that the drug is homogeneously dispersed in an amorphous state inside the microspheres. The in-vitro dissolution profile of acyclovir from chitosan microspheres is slower than that for the raw drug. Results from in-vivo ocular administration of acyclovir-loaded microspheres to the rabbit eye show prolonged high concentrations of acyclovir and increased AUC values. The microparticulate drug-carrier seems a promising means of topical administration of acyclovir to the eye.
阿昔洛韦在眼表上皮的生物利用度较低，当以眼膏形式给药时，必须每四小时给药一次。为了促进药物的长效释放并提高其眼部生物利用度，已采用乳化技术制备了载阿昔洛韦的壳聚糖微球。通过体外溶出试验和对兔眼进行体内眼部给药，对所得的微粒药物递送系统的形态和理化特性进行了表征。结果表明，所得微球总是相当小——90%的颗粒直径小于或等于25微米（即d90%从不超过25微米），理化表征表明药物以无定形状态均匀分散在微球内部。壳聚糖微球中阿昔洛韦的体外溶出曲线比原料药慢。将载阿昔洛韦微球对兔眼进行体内眼部给药的结果表明，阿昔洛韦的浓度长时间保持较高水平，且AUC值增加。微粒药物载体似乎是阿昔洛韦眼部局部给药的一种有前景的手段。
