RESUMEN
Oral solid dosage forms that contain APIs in the amorphous state have become commonplace because of many drug substances exhibiting poor water solubility, which negatively impacts their absorption in the human GI tract. While micronization, solvent spray-drying, and hot-melt extrusion can address solubility issues, spray coating of the APIs onto beads and tablets offers another option for producing amorphous drug products. High-level comparisons between bead and tablet coating technologies have the potential for simpler equipment and operation that can reduce the cost of development and manufacturing. However, spray coating directly onto tablets is not without challenges, especially with respect to meeting uniformity acceptance value (AV) criteria, comprising accuracy (mean) and precision (variance) objectives. The feasibility of meeting AV criteria is examined, based on mathematical models for accuracy and precision. The results indicate that the main difficulty in manufacturing satisfactory drug-layered tablets by spray coating is caused by the practical limitations of achieving the necessary coating precision. Despite this limitation, it is shown that AV criteria can be consistently met by appropriate materials monitoring and control as well as processing equipment setup, operation, and maintenance.
RESUMEN
The relationships between coating uniformity and efficiency were explored for tablet coating processes in pan coaters. The factors affecting the size of the spray zone were modeled using one-dimensional deposition analysis of spray droplets. This model was incorporated into the analytical model developed for coating uniformity by Choi et al. (AAPS PharmSciTech 22(7), 2021) that farther elucidated the effects of tablet shape and bed porosity. The results were compared with literature data on coating efficiency. The variables examined included tablet shape and size, coating time, pan speed, atomizing and pattern air flow rates, bed porosity, spray rate, batch size, coating solution concentration, spray gun-to-bed distance, and pan diameter. It is shown that, except for pan diameter and atomizing air flow rate, variables that improve coating efficiency adversely affected coating uniformity and vice versa. Implications of these relationships are discussed to improve formulation, process, and equipment designs.
Asunto(s)
Composición de Medicamentos , ComprimidosRESUMEN
Novel mathematical models were developed to predict inter-tablet coating uniformity in terms of coefficients of variation (CV) and acceptance values (AV) for cylindrical tablet pan coaters, operating in batch and continuous modes. The models, based on binomial coating spray and tablet movement distribution functions and on bed geometry, yielded equations and results that are in good agreement with previously reported experimental data, most empirical expressions, and more computationally intensive models. The new model equations are readily useable for process analysis, optimization, scale-up, and manufacturing design and control.
Asunto(s)
Composición de Medicamentos/métodos , Modelos Teóricos , ComprimidosRESUMEN
INTRODUCTION: Pharmaceutical coating processes have generally been transformed from what was essentially an art form in the mid-twentieth century to a much more technology-driven process. AREAS COVERED: This review article provides a basic overview of current film coating processes, including a discussion on polymer selection, coating formulation additives and processing equipment. Substrate considerations for pharmaceutical coating processes are also presented. EXPERT OPINION: While polymeric coating operations are commonplace in the pharmaceutical industry, film coating processes are still not fully understood, which presents serious challenges with current regulatory requirements. Novel analytical technologies and various modeling techniques that are being used to better understand film coating processes are discussed. This review article also examines the challenges of implementing process analytical technologies in coating operations, active pharmaceutical ingredients in polymer film coatings, the use of high-solids coating systems and continuous coating and other novel coating application methods.
Asunto(s)
Composición de Medicamentos , Sistemas de Liberación de Medicamentos , Preparaciones Farmacéuticas/química , Polímeros/química , Comprimidos Recubiertos/química , Química Farmacéutica/métodos , Excipientes , Tecnología Farmacéutica/métodosRESUMEN
BACKGROUND: Polymeric film coatings have been applied to pharmaceutical solids for decorative, protective, or functional purposes. The application process is quite complex, with variables related to the coating formulation, substrate properties, processing parameters, and interactions thereof, all of which can affect product performance. OBJECTIVE: This article describes a number of experimental techniques used to determine the physical, mechanical, adhesive, thermal, and permeability properties of free and applied films. These analytical tools can be used to optimize product performance, advance our knowledge of the film formation process, and investigate interactions between the coating and the solid surface. CONCLUSION: Through a better understanding of film-coating processes, the cause of problems that arise during manufacturing, defects observed in the coating, and changes in performance upon subsequent storage may be more quickly and accurately resolved.