Optimization of mucoadhesive microspheres of acyclovir by applying 32 full factorial design

The purpose of this research was to formulate and evaluate mucoadhesive rnicrospheres of acyclovir. Acyclovir mucoadhesive microspheres containing ethyl cellulose as carrier polymer and Carbopol 940 as mucoadhesive polymer were prepared by an emulsion solvent evaporation technique. The morphological characteristics of the mucoadhesive microspheres were studied under a scanning electron microscope. Microspheres were discrete. spherical. free flowing and showed a good percentage of drug entrapment efficiency. An in vitro mucoadhesive test showed that acyclovir mucoadhesive microspheres adhered more strongly to the gastric mucous layer and could retain for an extended period of time. A 3(2) full factorial design was employed to study the effect of independent variables, amount of ethyl cellulose (X,) and amount of Carbopol 940 (X-2) on dependent variables. i.e. drug entrapment efficiency, Q(1h), t(yo) and mucoadhesive strength parameter. The amount of ethyl cellulose and Carbopol 940 significantly affected on all selected dependent variables. The optimized batch exhibited a high drug entrapment efficiency of 72 %, h 27 %, t(yo)549 mm and mucoadhesion strength 21.2g. In vitro release of acyclovir was sustained up to 12 h. The formulation was found to be stable after two months stability study at accelerated condition. Overall, the developed formulation was stable with sustain release of acyclovir over 10-12 h periods: hence can be a viable alternative to conventional dosage forms.