Preparation and release characteristics of polymer-reinforced and coated alginate beads

Characterization of Bacillus mojavensis KJS-3 for industrial applications

One of the strains of the Bacillus mojavensis group, Bacillus mojavensis KJS-3 (B. mojavensis KJS-3), which has been demonstrated to play a role in protecting plants against diseases as a bacterial endophyte and in reducing the accumulation of mycotoxins generated by an endophytic fungus, was recently discovered in food waste. In this study, the identification and characterization of B. mojavensis KJS-3 was performed via TEM analysis, API-zym test, API 50 CHB test, assays of catalase and oxidase activity, lactic acid production, stability under various conditions, antibiotic susceptibility, and cellular fatty acid composition. The overall results of this study demonstrate that B. mojavensis KJS-3 may have great potential as a probiotic product, as this bacterium is quite stable in somewhat harsh environments. B. mojavensis KJS-3 was positive on oxidase and catalase tests, and the conversion rate of glucose to lactic acid was 58.9%. Finally, anteiso-C(15:0) (43.10%) was identified as the major fatty acid.

Enhanced Delivery of Bifidobacteria and Fecal Changes after Multiple Oral Administrations of Bifidobacteria-loaded Alginate Poly-l-lysine Microparticles in Human Volunteers

Enhanced delivery of bifidobacteria and fecal changes were compared following multiple oral administrations of protected bifidobacteria-loaded alginate poly-l-lysine microparticles (bap-microparticles) and unprotected bifidobacteria cultures over a period of 1 month to healthy human volunteers as preliminary in vivo studies. When bap-microparticles were orally administered, enhanced delivery of bifidobacteria was achieved. The viability of the bifidobacteria was significantly increased approximately 11.5-30 times (1.06-1.48 log cycles) during the ingestion period when compared with the bifidobacteria culture group (p < 0.05). However, other gut microflora such as bifidobacteria, enterobacteriaceae, lactic acid bacteria, and staphylococci in feces were not significantly different between the two groups. Encapsulated bifidobacteria resulted in more frequent defecation and decreased fecal viscosity.

Alginate in drug delivery systems

Alginates are established among the most versatile biopolymers, used in a wide range of applications. The conventional use of alginate as an excipient in drug products generally depends on the thickening, gel-forming, and stabilizing properties. A need for prolonged and better control of drug administration has increased the demand for tailor-made polymers. Hydrocolloids like alginate can play a significant role in the design of a controlled-release product. At low pH hydration of alginic acid leads to the formation of a high-viscosity "acid gel." Alginate is also easily gelled in the presence of a divalent cation as the calcium ion. Dried sodium alginate beads reswell, creating a diffusion barrier decreasing the migration of small molecules (e.g., drugs). The ability of alginate to form two types of gel dependent on pH, i.e., an acid gel and an ionotropic gel, gives the polymer unique properties compared to neutral macromolecules. The molecule can be tailor-made for a number of applications. So far more than 200 different alginate grades and a number of alginate salts are manufactured. The potential use of the various qualities as pharmaceutical excipients has not been evaluated fully, but alginate is likely to make an important contribution in the development of polymeric delivery systems. This natural polymer is adopted by Ph.Eur. It can be obtained in an ultrapure form suitable for implants. This review discusses the present use and future possibilities of alginate as a tool in drug formulation.

Controlled release of dual drug-loaded hydroxypropyl methylcellulose matrix tablet using drug-containing polymeric coatings

A dual drug-loaded hydroxypropylmethylcellulose (HPMC) matrix tablet simultaneously containing drug in inner tablet core and outer coated layer was formulated using drug-containing aqueous-based polymeric Eudragit RS30D dispersions. Effects of coating levels, drug loadings in outer layers, amount and type of five plasticizers and talc concentration on the release characteristics were evaluated on the characteristics in simulated gastric fluid for 2 h followed by a study in intestinal fluids. Melatonin (MT) was selected as a model drug. The surface morphology of dual drug-loaded HPMC tablets using scanning electron microscope (SEM) was smooth, showing the distinct coated layer with about 75-microm coating thickness at the 15% coating level. Unlike the uncoated and conventionally coated HPMC tablet, the dual drug-loaded HPMC matrix tablet gave a biphasic linear release, showing a zero-order for 4 h (first) followed by another zero-order release when fitted using linear regression (r(2) = 0.99). As the coating levels (15, 25%) increased, the release rate was further decreased. The biphasic release profiles of dual drug-loaded HPMC matrix tablet was unchanged except when 25% coating level containing 0.5% drug concentration was applied. As the drug concentration in polymeric coating dispersion increased (0.25-1.0%), the amount of drug released increased. The time for the first linear release was also advanced. However, the biphasic release pattern was not changed. The biphasic release profiles of dual drug-loaded HPMC matrix tablet were highly modified, depending on the amount and type of five plasticizers. Talc (10-30%) in coating dispersion as an anti-sticking material did not affect the release profiles. The current dual drug-loaded HPMC matrix tablet, showing biphasic release profiles may provide an alternative to deliver drugs with circadian rhythmic behaviors in the body but needs to be further validated in future in human studies. The dual drug-loaded coating method is also interesting for the modified release of poorly water-soluble drugs because solubilizers and other additives can be added in drug-containing polymeric coating dispersions.

Biphasic release characteristics of dual drug-loaded alginate beads

The dual drug-loaded alginate beads simultaneously containing drug in inner and outer layers were prepared by dropping plain (single-layered) alginate beads into CaCl2 solution. The release characteristics were evaluated in simulated gastric fluid for 2 h followed by intestinal fluids thereafter for 12 h. The surface morphology and cross section of dual drug-loaded alginate beads was also investigated using scanning electron microscope (SEM). The poorly water-soluble ibuprofen was chosen as a model drug. The surface of single-layered and dual drug-loaded alginate beads showed very crude and roughness, showing aggregated particles, surface cracks and rough crystals. The thickness of dual drug-loaded alginate beads surrounded by outer layer was ranged from about 57 to 329 microns. The distinct chasm between inner and outer layers was also observed. In case of single-layered alginate beads, the drug was not released in gastric fluid but was largely released in intestinal fluid. However, the release rate decreased as the reinforcing Eudragit polymer contents increased. When the plasticizers were added into polymer, the release rate largely decreased. The release rate of dual drug-loaded alginate beads was stable in gastric fluid for 2 h but largely increased when switched in intestinal fluid. The drug linearly released for 4 h followed by another linear release thereafter, showing a distinct biphasic release characteristics. There was a difference in the release profiles between single-layered and dual drug-loaded alginate beads due to their structural shape. However, this biphasic release profiles were modified by varying formulation compositions of inner and outer layer of alginate beads. The release rate of dual drug-loaded alginate beads slightly decreased when the outer layer was reinforced with Eudragit RS100 polymers. In case of dual drug-loaded alginate beads with polymer-reinforced outer layer only, the initial amount of drug released was low but the initial release rate (slope) was higher due to more swellable inner cores when compared to polymer-reinforced inner cores. The current dual drug-loaded alginate beads may be used to deliver the drugs in a time dependent manner.