DESIGN FORMULATION AND EVALUATION OF FLOATING MICROSPHERES OF TIMOLOL
Ch. Taraka Ramarao* and T. Yugandhar
ABSTRACT
The goal of present investigation attempt was made to prepare
microspheres of timolol employing by using various polymers like
HPMC K15M, Eudragit S100 and ethyl cellulose to achieve an oral
controlled release of the timolol. In the present study nine
formulations were formulated by using HPMC K15M, Eudragit S100
and EC in various proportions (1:1, 1:2, 1:3). All the formulations
were subjected to (%) Percentage yield, drug content, buoyancy time
and entrapment efficiency, in vitro dissolution and release kinetics
shown satisfactory results. Entrapment efficiency was increased with
increased polymer concentration. On the basis of release data and
graphical analysis formulation F6 shown good controlled release
profile with maximum entrapment efficiency because of high polymer
concentration. The co-efficient of determination indicated that the release data was best
fitted with zero order kinetics. Higuchi equation explains the diffusion controlled release
mechanism. The diffusion exponent ānā values of Korsemeyer- Peppas model was found to
be in the range of more than 1 for the Timolol floating microspheres prepared with drug and
Eudragit indicating super case II transport diffusion mechanism of drug through timolol
floating microspheres. The floating microsphere is possible to formulate promising
controlled release timolol. The results it can be concluded that the drug release from the
floating microspheres diffusion controlled. The formulations showed best appropriate balance
between buoyancy and in vitro drug release. The floating microspheres are stable during shelf
life.
Keywords: Micro spheres; HPMC K 15M; Buoyancy; Entrapment efficiency; Percentage yield.
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