STATISTICAL INTERPRETATION AND OPTIMIZATION OF VALSARTAN FLOATING TABLETS USING BOX-BEHNKEN DESIGN

Objective: The main purpose of this study was to formulate and statistically evaluate 300 mg floating tablets of valsartan. Methods: Floating tablets of valsartan was prepared in 16 station rotary punching machine by considering 300 mg of valsartan as drug, 40-60 mg of hydroxypropyl methylcellulose (HPMC) K100M and 20-40 mg of poly (styrene-divinylbenzene) as polymers and 20 mg of sodium bicarbonate as gas generating agents. Since upper stomach has maximum therapeutic window for valsartan absorption, hence Gastroretentive Floating Tablets (GRFTs) was prepared by implementing Box-Bentham Design. The pre and post compression parameters were optimized using Statistica 10 software. From the in vitro buoyancy and drug release studies and interpretation of statistical outcomes viz. Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), Root Mean Squared Error (RMSE), Dissolution Efficiency (DE), Mean Dissolution Time (MDT), desirability study, it was concluded that batch VF5 formulation was found to be the most optimized formulation. Results: The floating time of VF5 was found to be 132±0.33 sec, in vitro buoyancy time was 18 h, Akaike Information Criterion (AIC) was 54.97, Bayesian Information Criterion (BIC) was 5.13, percentage dissolution efficacy was 56.39%, mean dissolution time was 5.19hr. Further, six-month stability study was performed as per ICH QIA guideline. After performing two-way ANOVA within stability study response variables, it was confirmed that the interaction was most significant. Conclusion: Valsartan floating drug delivery system was successfully developed by considering HPMC K100M and poly (styrene-divinylbenzene) as polymers. Among all the nine batches, VF5 was found to be the best-optimized batch.

Preparation and Characterization of Polyvinyl Acetate (Kollidon® SR) Microspheres Containing Diclofenac Sodium II: Effect of core loading

Diclofenac Sodium (DS) loaded Kollidon® SR (Polyvinyl acetate and povidone based matrix retarding polymer) microspheres of different drug loading were prepared using W/O emulsification solvent evaporation technique. Polymeric solution containing the DS was emulsified in light liquid paraffin (LLP) which was initially emulsified by 1% (w/w of the continuum) lipophilic surfactant Span 60. The study was conducted to investigate the effect of different core to polymer ratio (0.5: 1, 1 : 1, 1.5 : 1 and 2 : 1) on microsphere size, encapsulation efficiency and release kinetics of DS. Microsphere size was decreased with increased core loading. However, higher encapsulation efficiency was observed with higher core loading. A square root of time dependent release of DS was observed from the KSR microspheres. Increased core loading caused faster release of DS. Release rates of DS were affected by different DS content in the core. Normalized release rates were also found to be increased with high core loading. Mean dissolution time (MDT) and t50 values were also calculated and were found to be affected significantly by different DS loading to KSR microspheres. Low DS loading increased MDT. Key words: Kollidon® SR; Diclofenac Sodium; Microsphere; Solvent evaporation technique; Mean dissolution time. DOI: 10.3329/dujps.v8i2.6025 Dhaka Univ. J. Pharm. Sci. 8(2): 117-122, 2009 (December)