gastroretention

Gastroretention is advisable for metformin hydrochloride due to its site specific absorption and low bioavailability (60%). Therefore, the attempts have been carried out in present study to formulate bioadhesive microspheres of metformin hydrochloride. Microspheres provide precise control on drug release and bioadhesion is useful to obtain gastroretention for improvement in bioavailability. Drug loaded microspheres of bioadhesive polymers were prepared by ionic gelation method. Hydroxypropyl methyl cellulose (HPMC), hydroxypropyl cellulose (HPC) and methyl cellulose (MC) were used as bioadhesive polymers. Microspheres were prepared by using various ratios of sodium alginate to respective polymer(s). One gram of drug was added in 50ml solution of polymers separately. Microspheres were collected in 10% w/v calcium chloride solution with constant stirring. Formulation MS2 (sodium alginate: HPC; 1:1) was found to be the best among all. For MS2, percent yield (65.5%), drug entrapment efficiency (72±0.56%), particle size (851 µm), in vitro wash off test (63.9 %), in vitro drug release (80.77 %) etc. Some process parameters viz orifice diameter of needle used to pass polymer solution, dropping height and stirring speed were studied. It was observed that as the orifice diameter of needle decreased from needle no. 18 to 23, the microspheres were more spherical with retention in their shape and needle no. 20 was found to be optimum. More spherical microspheres were observed with decrease in dropping height and optimum was found to be 6 cm. With increase in stirring speed from 250 to 750 RPM, drug entrapment efficiency decreased. 

This work investigates the development and evaluation of hydrodynamically balanced systems (HBSs) of aceclofenac as single unit capsule. The various HBS capsules were formulated by physical blending of aceclofenac with carbopol 934, hydroxypropyl methyl cellulose, pectin in different ratios. These HBS capsules were evaluated for weight uniformity, drug content uniformity, in vitro floating behavior and drug release in simulated gastric fluids (pH 1.2). All these formulated HBS capsules containing aceclofenac were floated well over 5 hours with no floating lag time, and also showed sustained in vitro drug release in simulated gastric fluid over 5 hours. The aceclofenac release was found to be more sustaining with the addition of polymer i.e. carbopol 934 and hydroxyl propyl methyl cellulose. The drug release pattern of these aceclofenac HBS capsules (F-1, F-4, F-5 and F-8) were correlated well with first order model where F-6 to F-7 and F-2 toF-3 was correlated well with Higuchi model Korsmeyer-Peppas model with Fickian diffusion mechanism. All the experimental results showed that the aceclofenac HBS capsule successfully sustain the drug release along with improve the oral bioavailability of candidate drug.