Coating Articles

new chemical entity often is first formulated as a free-flowing granulation for encapsulation within hard gelatin capsules. During the course of clinical development, the drugcontaining granulation usually is modified for compaction into a tablet product. The tablet product subsequently may be film coated for taste masking, identification, or other purposes. Tablets are the most preferred and widely used dosage form because of their ease of administration, lower cost of manufacture, and elegance. In this article, we describe a means of producing tablet dosage forms (specifically, compression-coated tablets) from granulations or blends that do not readily form a compact. The compression-coating granulation or blend can be preformulated to provide desired functionalities to the coating.

C ellulose acetate (CA) is a polymeric excipient commonly used in formulating pharmaceutical dosage forms. CA can be used in direct compression or powder granulation for making tablets (1). It is well known that CA is used for forming the semipermeable membrane in an osmotic delivery system (2–4).

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Consideration of the key process variable will define the ease with which coating processes can be transferred from development to production. This study investigates those factors influencing atomization from two spray guns and examines how development-scale procedures o­n interchangeable drum coating equipment compare with those typically used in a production environment.

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The goal of the present study was to evaluate the influence of the formulation and operating conditions o­n pellet preparation by pan technique. To this end, a new pelletization process, typified by the application of powdered drug o­n sugar-based cores using the GS coating system was studied. Inert cores were intermittently treated with micronized drug powder and adhesive solution. This treatment led to the formation of multiple layers of drug particles around an inert core resulting in the production of pellets that can further be coated by different polymers to obtain modified release formulations. Different procedures have been used to evaluate a series of important parameters such as initial core weight; speed of powder application; speed, type, and position of the atomizers; atomization degree; temperature; and air cap.

Good yield of drug layering was obtained by adjusting the quantity of both the drug powder to apply and the binder solution.

Abstract

The effects of coating thickness, type of adhesive, and type and concentration of enhancer o­n the mechanical properties of two acrylic pressure-sensitive adhesives (PSAs) were investigated using a 24 factorial design and an optimization technique. Sixteen formulations containing 0% or 10% of either caprylic acid or methyl laurate in two different PSAs, namely Duro-Tak® 87-2196 and Duro-Tak® 87-2097, were prepared. The adhesive properties of these laminates were evaluated by applying the 900 Dynamic Adhesive Strength Peel Test (900 DASPT) and 1800 Release Liner Peel Test (1800 RLPT). Coating thickness, concentration of enhancer, and type of adhesive did affect the 900 DASPT. For the 1800 RLPT, the most significant factors were coating thickness and concentration of enhancer, with a strong interaction observed between the two.

Abstract

Amylose-ethylcellulose film coatings obtained from organic-based solvents were investigated as potential vehicles for colonic drug delivery. Amylose, in the form of an amylose-butan-1-ol dispersion, and ethylcellulose, dissolved in either ethyl lactate, ethanol, or propanol and plasticized with dibutyl sebacate, were mixed in various proportions and applied using a fluidized bed coater to achieve a range of film thicknesses o­n 5-aminosalicylic acid pellets. Drug release from the coated pellets was assessed under gastric and small intestinal conditions in the presence and absence of pepsin and pancreatin using dissolution methodology, and also within a simulated colonic environment involving fermentation testing with human feces in the form of a slurry. Under upper gastrointestinal tract conditions, the rate and extent of drug release were found to be related to the thickness of the coating and the ratio of amylose to ethylcellulose within the film.

Wurster coating provides excellent film uniformity and god active-component distribution. The authors describe the results of a study using the Wurster method with positron emission particle tracking technology.

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AbstractAn instrumentation and automation system for a side-vented pan coater with a novel air-flow rate measurement system for monitoring the film-coating process of tablets was designed and tested. The instrumented coating system was tested and validated by film-coating over 20 pilot-scale batches of tablets with aqueous-based hydroxypropyl methylcellulose (HPMC). Thirteen different process parameters were continuously measured and monitored, and the most significant o­nes were logged for analysis. Laser profilometry was used to measure the surface roughness of the coated tablets. The instrumentation system provided comprehensive and quantitative information o­n the process parameters monitored. The measured process parameters and the responses of the film-coated tablet batches showed that the coating process is reproducible. The inlet air-flow rate influenced the coating process and the subsequent quality of the coated tablets.

Using X-Ray Absorption Spectroscopy to Study the Speciation and Coordination of Lead Binding to Humic Materials In this study X-ray absorption was used to determine the effect of pH on the coordination of lead to humin and sphagnum peat moss. The authors determined the oxidation state and the coordination of lead to both humin and sphagnum peat moss using X-ray near edge structure and extended X-ray absorption fine structure spectroscopy.

In the past few years, many published articles have detailed the developments in the enteric coating process (1). Significant progress has been made in the coating of both hard gelatin capsules and softgels (2–4), and some progress has been made in the coating of small particles such as beads and granules. In addition, improvement has been seen in the enteric coating systems for tablets. One example is the advances in applying colored latex enteric films.

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