Abstract
Aims: 1) To study the effect of some formulation variables on drug load, encapsulation efficiency, swelling ratio, mucoadhesion and drug release. 2) Optimize the mucoadhesion capabilities for targeting drug absorption and release-controlling capabilities of alginate beads.
Methodology: Alginate beads were prepared by dripping sodium alginate gel into calcium chloride solution and then dried overnight at ambient temperature. The effects of alginate concentration, cross linker concentration, cross linking time, volume of cross linking solution and drug/polymer ratio on drug load, encapsulation efficiency, swelling ratio, mucoadhesion and drug release were investigated. Formulae containing sodium lauryl sulfate (SLS), gabapentin-ethylcellulose solid dispersion, mixture of free drug and solid dispersion were prepared for modifying the drug release rate.
Results: Mucoadhesion of alginate beads was shown to be decreased upon adding SLS (30% after 8 hrs). Drug release was so fast (92.46% after 2 hrs). The incorporation of solid dispersion has led to well accepted mucoadhesion (74.44% after 8 hrs) as well as release properties (93.35% after 10 hrs) Beads containing mixtures of drug and ethylcellulose-drug solid dispersion showed acceptable mucoadhesion (74.44% after 8 hrs) and control of gabapentin release (93.35% after 10 hrs). Statistical analysis of variance between groups was performed using the one-way layout ANOVA with duplication. Significant differences in mean values were evaluated by Student's unpaired t test (P < 0.05).
Conclusion: A finally optimized formula was suggested by incorporating a combination of solid dispersion and free gabapentin in alginate system to achieve burst release of gabapentin and hence fast effect (33.417% was released during the first 30 minutes in fasting-simulated conditions) and controlled release (91.217% after 6 hrs).