Preparation and characterization of a customized cellulose acetate butyrate dispersion for controlled drug delivery

Airborne Microorganisms From Livestock Production Systems and Their Relation to Dust

Large amounts of airborne microorganisms are emitted from livestock production. These emitted microorganisms may associate with dust, and are suspected to pose a risk of airborne infection to humans in vicinity and to animals on other farms. However, the extent to which airborne transmission may play a role in the epidemic, and how dust acts as a carrier of microorganisms in the transmission processes is unknown. The authors present the current knowledge of the entire process of airborne transmission of microorganisms-from suspension and transportation until deposition and infection-and their relation to dust. The sampling and the mitigation techniques of airborne microorganisms and dust in livestock production systems are introduced as well.

Solubility-modulated asymmetric membrane tablets of triprolidine hydrochloride: statistical optimization and evaluation

The aim of the present study was to develop asymmetric membrane (AM) tablets for controlled delivery of highly water-soluble antihistaminic drug triprolidine hydrochloride. The solubility of triprolidine hydrochloride was modulated through the incorporation of coated sodium chloride crystals encapsulated with asymmetric membrane coating polymer, cellulose acetate butyrate. Formulation of AM tablets was based on a 2(3) factorial design to study the effect of formulation variables, namely, polymer concentration, level of pore former, and amount of osmogen on the in vitro release. Core tablets prepared by wet granulation and coated with asymmetric membrane by a dip coating method were evaluated. Statistical analysis was done with the Design Expert Software 8.0.2 (USA), and the polynomial equation generated by Pareto charts was used for validation of the experimental design. The interaction chart and response surface plots deduced the simultaneous effect of independent variables on in vitro drug release. The in vitro drug release was inversely proportional and directly related to the level(s) of polymer and pore former in the membrane, respectively. The level of osmogen not only increased the osmotic pressure but also controlled the drug release due to a common ion effect. The drug release of the optimized formulation (F6) followed zero-order kinetics, which would be capable of reducing the administration, and was stable over 3 months. SEM photographs revealed asymmetry in membrane structure.

Controlled Release Multiparticulate Beads Coated with Starch Acetate: Material Characterization, and Identification of Critical Formulation and Process Variables

The objectives of the present investigation were to prepare and characterize starch acetate (SA) with high degree of substitution (dS) and to study its prospect as film-forming agent in a controlled-release multiparticulate drug delivery system. As a part of the development process by quality by design, the objectives also included identification of critical formulation and process variables that affect the release of a drug. SA, a relatively new polymer, was characterized because it showed good film-forming properties. SA with dS 2.9 was synthesized from corn starch by paste disruption technique. It was compared with the raw material, starch, by Fourier transform infrared spectroscopy, X-ray diffraction, and molecular mass analysis. Viscosity of SA solution increased logarithmically with the polymer concentration. At higher polymer concentrations (1.5-5.0%), the solutions showed pseudoplastic behavior. Among the plasticizers tested, triacetin and triethyl citrate yielded free films with acceptable mechanical properties. The glass transition temperature (Tg) of the films could be well controlled by these plasticizers. Unplasticized film showed a Tg of 31.8 degrees C. A trend was found that increase in triacetin concentration in SA films resulted in increase in permeability coefficient for tritiated water. Scanning electron microscopic photographs showed a clear and smooth plasticized film compared to rough unplasticized film. Dyphylline-loaded beads were coated with highly substituted SA to evaluate the main effects of the formulation and process variables on the release of the drug and to figure out the reliability of the screening design. A seven-factor, twelve-run Plackett-Burman screening design was used. The response variables were cumulative percent of drug released in 0.5, 1, 4, 8, and 12 hr. Quantitative evaluation of the design revealed that coating weight gain, plasticizer concentration, and post-drying temperature had greater influence on the drug release than the others. The main effects on drug release after 12 hr decreased in the following order: coating weight gain (-7.81), plasticizer concentration (4.96), postdrying temperature (-2.51), SA concentration (-0.80), inlet temperature (0.51), postdrying time (-0.31), and atomizing pressure (-0.28).

Identification and quantitation of extractables from cellulose acetate butyrate (CAB) and estimation of their in vivo exposure levels

The purpose of this study was to qualitatively and quantitatively determine potential cellulose acetate butyrate (CAB) extractables in a way to meaningfully predict the in vivo exposure resulting from clinical administration. Extractions of CAB-381-20 were performed in several solvent systems, consistently resulting in the detection of three extractables. The extractables have been identified as acetic acid, butyric acid, and E-2-ethyl-2-hexenoic acid (E-EHA) by LC/UV, LC/MS and NMR. Extraction studies of CAB powders in acetonitrile/phosphate buffer demonstrated quantitative extraction in 1 h for acetic acid (approximately 150 microg/g), butyric acid (approximately 200 microg/g), and EHA (approximately 20 microg/g). Subsequently, extraction studies for CAB powders and coated tablets in USP simulated gastric and intestinal fluids were performed to evaluate potential in vivo exposure. Similarly, acetic and butyric acids were quantitatively extracted from CAB-381-20 powder after 24 h exposure in both USP simulated fluids. The amounts of EHA extracted from CAB powder after 24 h were determined to be 2 and 16 microg/g in USP simulated gastric and intestinal fluids, respectively. After 24 h exposure in USP simulated fluids, the maximum amount of EHA extracted corresponds to < 0.3 microg of EHA per tablet. Pepsin and pancreatin in USP simulated fluids had no effect on EHA extraction and quantitation.

Aqueous starch acetate dispersion as a novel coating material for controlled release products

The aim of this study was to evaluate film-formation properties of a novel, organic solvent-free aqueous dispersion of potato starch acetate (SA; degree of substitution 2.8) and its ability to control drug release from a coated tablet. Initially, film-formation mechanisms and drug permeabilities of both organic solvent and dispersion-based SA free films (prepared by cast or spraying techniques) were investigated. The SA dispersion was suitable for the fluid-bed coating process, forming strong films with complete coalescent polymeric spheres. The model compounds predominantly permeated via the micro-pores of SA free films, which resulted from the leaching of water-soluble excipients from the dispersion. Thus, the permeation rate depended on the film structure rather than the physico-chemical properties of the penetrant. In the case of SA-coated tablet, drug release was sustained when the coating level was increased (from 12% to 20%, stated as a weight gain), and also as lipophilicity of the drug increased. When compared to the reference polymer dispersion (Surelease), SA coatings showed better mechanical properties against the osmotic pressure caused by a hydrophilic core tablet. These results clearly demonstrate that SA dispersion has high utility as a novel aqueous coating material for controlled release products.