ABSTRACT
Aim: The application of factorial experimental design to evaluate the effect of particle size, capsule surface coating and binder concentration on the in vitro controlled release profile of metronidazole from encapsulated granules. Methodology: Metronidazole granules were prepared by the wet granulation technique and encapsulated in hard gelatin capsule shells. Eudragit® L-100 and Landolphia owariensis latex served as primary and secondary coatings respectively on 50 or 75% of capsule surface. The three formulation factors (% capsule surface coating, matrix former concentration and particle size) were subjected to a 2x3x4 factorial design experiment using the software (JMP 4.0.4, SAS Inc. USA). Gradient drug release studies were conducted in three media; firstly in media of pH 1.2 for 2 h, pH 6.8 for 3 h and finally pH 7.4 until exhaustion of drug release. The drug release data were subjected to kinetic treatment to establish operational release kinetics such as zero order, first order, Higuchi, Hixon Crowell and Kitazawa, while the power law enabled the prediction of mechanism of drug release. Results: Results showed that % capsule surface coated with Landolphia owariensis latex and particle size significantly (p<0.05) contributed to time of drug release (T7.4) at pH 7.4. In tandem with this, maximum amount of drug released (D7.4) at pH 7.4 was significantly (p<0.05) affected by particle size alone. A few batches were characterized by anomalous transport while over 80% were associated with super case 11 type of release. Conclusion: We therefore conclude that, factorial experimental design identified Landolphia owariensis latex coating and particle size of granules as being chiefly responsible for drug release variations.
ABSTRACT
Objective: The objectives of this study were to identify stable anhydrous emulsions via pseudo ternary phase diagram, optimize artemether-loaded batches using factorial design and subsequently evaluate the antimalarial activity. Methodology: Using labrasol®, triacetin® and lauroglycol 90® as the surfactant, oil and co-surfactant respectively, pseudo ternary phase diagram was generated from the quantitative titration of water with the anhydrous emulsion. Stable combinations from the phase diagram were subjected to a 23 full factorial experimental design. The 22 softwaregenerated formulations were experimentally formulated and characterized for droplet size, polydispersity index, viscosity and thermodynamic stability. Droplet size was chosen and subsequently fitted into the Response column of the software, thus prompting the generation of graphs and Desirability table of 125 predicted formulations. Out of the 125 predictions, three with the least droplet sizes (less than 100 nm) were adjudged as optimized batches. Subsequently, they were formulated, converted to powder by adsorption on magnesium aluminum metasilicate and evaluated. Antimalarial effectiveness of the drug-loaded formulation was also investigated. Results: Triacetin® most significantly (P<0.05) contributed to droplet size variation. The droplet size of the experimental formulations approximated that of the statistical predictions. The anhydrous emulsions (AEs) were powderable and the granulations rated fair and passable according to Carr’s scale. Artemether-loaded anhydrous emulsion (AE) demonstrated highest antimalarial activity. Conclusion: We therefore conclude that optimization proved a useful tool for the identification of excipient proportions with optimal effects.