Influence of Film Additives on Stabilizing Drug Release Rates from Pellets Coated with Acrylic Polymers

Abstract

The objective of this study was to investigate the influence of talc and triethyl citrate (TEC) on stabilizing the drug release rates following curing and storage at elevated temperature of pellets coated with an aqueous acrylic polymeric dispersion. Core pellets containing anhydrous theophylline (20%), microcrystalline cellulose, and polyvinylpyrrolidone were prepared by extrusion-spheronization. The aqueous dispersions were prepared by adding up to 30% TEC as a plasticizer and talc up to 200% as an antiadherent to a mixture of Eudragit RS 30D/RL 30D (95:5). The theophylline pellets were coated in a fluidized-bed coating unit and then cured at elevated temperatures. Theophylline pellets were successfully coated with the Eudragit dispersions that contained up to 200% talc, based on the dry polymer weight, and the coating efficiency was greater than 93%. Our results demonstrated that the polymer, which was plasticized by TEC, was able to function as a film-forming agent for dispersions containing high levels of talc. No sticking of the coated pellets was observed during the coating process or during the curing or equilibrating phase, even with high levels of TEC in the film. The dissolution rate of theophylline from the coated pellets was delayed when the film coating dispersion contained high levels of talc. Additionally, the stability of the drug release profiles from the coated pellets after storage was significantly improved. Furthermore, a modified dissolution testing used to simulate mechanical stresses that may be encountered in vivo showed the film coated pellets would have sufficient strength. The results of this study demonstrated that high levels of film additives in the acrylic dispersion contributed to the stabilization of the drug release rates as well as the reproducibility of the coating process.

Effect of Eudragit® RS 30D and Talc Powder on Verapamil Hydrochloride Release from Beads Coated with Drug Layered Matrices

“…Traditionally talc powder is used as an anti-tacking agent at concentrations ranging from 25% to 100%, based on the weight of dry polymer, to facilitate the coating process (11). Talc has the ability to decrease the agglomeration tendency of pellets when coated with aqueous polymeric dispersions.…”

“…In aqueous systems the coalescence of individual colloidal particles and the interdiffusion of polymeric particles must occur to form a continuous film (10). This is accomplished during the coating process as a result of water evaporation, which generates surface tension effects and capillary forces among polymer particles (11). The slow rate of water evaporation coupled with its high latent heat of vaporization, however, is also responsible for the tackiness problems experienced with these systems (12).…”

“…The slow rate of water evaporation coupled with its high latent heat of vaporization, however, is also responsible for the tackiness problems experienced with these systems (12). Therefore, talc powder has been frequently used as an inert anti-tacking agent in aqueous-based acrylic colloidal dispersions when coating either single unit dosage forms (tablets) or multiparticulate units (3,11,13). Maejima and McGinity (11) reported that high levels of talc powder up to 200%, based on dry polymer weight, however, had a stabilizing effect on the release rate of theophylline from coated beads after storage at different conditions.…”

Influence of an Acrylic Polymer Blend on the Physical Stability of Film-Coated Theophylline Pellets

“…These include the addition of high levels of plasticizer (1) or talc (8), the inclusion of an immiscible, water-soluble non-ionic excipient (hydroxyethylcellulose) (5) or proteins (9), and the addition of silicon dioxide to the polymeric coating formulation (10). Another avenue of research that has been described in previous reports is the blending of high T g polymers which are miscible with the functional coating.…”

Effect of Antiadherents on the Physical and Drug Release Properties of Acrylic Polymeric Films

“…Most frequently, talc is used to decrease tackiness and is recommended for use with acrylic polymers (13). However, the addition of talc in coating formulations can result in sedimentation of the material during the spraying process, clogging of the spray nozzle, and incompatibilities with other materials in the coating and/or the substrate (14)(15)(16)(17)(18). Glyceryl monostearate (GMS) has been used as an alternative to talc (2,19,20).…”