Manju Rawat

Influence of selected formulation variables on the preparation of enzyme-entrapped eudragit S100 microspheres

The aim of this work is to study the influence of formulation parameters in the preparation of sustained release enzyme-loaded Eudragit S100 microspheres by emulsion solvent diffusion technique. A 32 full factorial experiment was designed to study the effects of the amount of solvent (dichloromethane) and stabilizers (Tween 20, 40, or 80) on the drug content and microsphere size. The results of analysis of variance test for both effects indicated that the test is significant. The effect of amount of stabilizer was found to be higher on both responses (SSY1=45.60; SSY2=737.93), whereas solvent concentration comparatively produced significant effect on the size of microspheres (SSY1=0.81; SSY2=358.83). Scanning electron microscopy of microspheres with maximum drug content (2.5 mL dichloromethane and 0.1 mL Tween 80) demonstrated smooth surface spherical particles with mean diameter of 56.83±2.88 µm. The effect of formulation variables on the integrity of enzyme was confirmed by in vitro proteolytic activity. The enteric nature of microspheres was evaluated and results demonstrated ∼6% to 7% release of enzyme in acidic medium. The release of enzyme from microspheres followed Higuchi kinetics. In phosphate buffer, microspheres showed an initial burst release of 20.34%±2.35% in 1 hour with additional 58.79%±4.32% release in the next 5 hours. Three dimensional response graphs were presented to visualize the effect of independent variables on the chosen response. Thus, Eudragit S100 microspheres can be successfully prepared for oral delivery of enzymes with desirable characters in terms of maximum loading and diffusion release pattern.

Development and In Vitro Evaluation of Alginate Gel–Encapsulated, Chitosan-Coated Ceramic Nanocores for Oral Delivery of Enzyme

The successful administration of protein and peptide drugs by oral route maintaining their active conformation remains a key challenge in the field of pharmaceutical technology. In the present study, we propose the use of a nanosize ceramic core-based system for effective oral delivery of acid-labile model enzyme, serratiopeptidase (STP). Ceramic core was prepared by colloidal precipitation and sonication of disodium hydrogen phosphate solution and calcium chloride solution at room temperature. The core was coated with chitosan under constant stirring and Fourier-Transform Infra Red Spectroscopy (FTIR) confirmed phosphoric groups of calcium phosphate linked with ammonium groups of chitosan in the nanoparticles; then the enzyme was adsorbed over the preformed nanocore. Protein-loaded nanocore was further encapsulated into alginate gel for enzyme protection. Prepared system was characterized for size, shape, loading efficiency, and in vitro release profile (pH 1.2 and pH 7.4). The effect of processing variables on the size of the core was evaluated to form small, uniform, and discrete nanocores. Stability and integrity of enzyme during processing steps was assessed by in vitro proteolytic activity. The prepared system was examined to be spherical in shape with diameter 925 ± 6.81 nm using TEM. The in vitro release data followed the Higuchi model, showing a low amount (26% ± 2.4%) of diffusion-controlled drug release (R2 = 0.9429) in acidic buffer up to a period of 2 to 6 hours, signifying the integrity of alginate gel in acid. In the alkaline medium sustained and nearly complete first order release of protein was observed up to a 6 hours. It is inferred that the protein-loaded ceramic core acts as a reservoir of the adsorbed enzyme and alginate gel provides protection to STP for controlled release in intestinal pH when compared to the enzyme solution.

Formulation optimization of double emulsification method for preparation of enzyme-loaded Eudragit S100 microspheres

The present study aimed to develop an oral sustained release microparticulate system for acid labile enzyme-Serratiopeptidase. A 32 full factorial experiment was designed to study the effects of the external aqueous phase volume and stabilizer (Tween® 80) concentration on the entrapment and size of Eudragit S100 microspheres prepared by a modified double emulsion solvent evaporation technique. The results of analysis of variance tests for both effects indicated that the test is significant. The effect of external aqueous phase volume was found to be higher on the entrapment efficiency of microspheres (SSY1 = 1362.63; SSY2 = 250.13), whereas Tween® 80 produced a significant effect on size of microspheres (SSY1 = 944.01; SSY2 = 737.26). Scanning electron microscopy of microspheres demonstrated smooth surface spherical particles. The effect of formulation variables on the integrity of enzyme was confirmed by in vitro proteolytic activity. Microspheres having maximum drug encapsulation (81.32 ± 3.97) released 4–5% enzyme at pH 1.2 in 2 h. The release of enzyme from microspheres followed Higuchi kinetics (R2 = 0.987). In phosphate buffer, microspheres showed an initial burst release of 25.65 ± 2.35% in 1 h with an additional 62.96 ± 4.09% release in the next 5 h. Thus, formulation optimization represents an economical approach for successful preparation of Eudragit S100 microspheres involving fewest numbers of experiments.