Effect of Curing Conditions and Plasticizer Level on the Release of Highly Lipophilic Drug from Coated Multiparticulate Drug Delivery System

Water-insoluble polymers as binders for pellet drug layering: Effect on drug release and performance upon compression

The objective of this study was to investigate the applicability of water-insoluble polymers as binders for pellet drug layering to extend the drug release. Carbamazepine was layered on sugar cores in fluidized bed coater using isopropanol (IPA):water solution or aqueous dispersion of ethylcellulose, polyvinyl acetate or ammonium-methylmethacrylate copolymer. Carbamazepine release was extended with all investigated water-insoluble polymers used as binder, without an additional coating layer. Drug release from pellets layered using IPA:water polymer solutions was dependent on polymer properties such as lipophilicity and pore-forming components, while from those layered with aqueous polymer dispersions, the release was dependent on the completeness of film formation during drug layering. Curing effect was observed only for pellets layered with Aquacoat® ECD and Eudragit® RS 30D. The drug release was not affected by compression when pellets were prepared with the flexible polymers Kollidon® SR or Kollicoat® SR 30D, however, it increased when brittle polymers such as ethylcellulose or Eudragit® RS were used. This problem could be minimized by using a higher amount of the binder, addition of a plasticizer or using polymers of higher viscosity grade. In conclusion, the use of water-insoluble polymers as binder for pellet drug layering is an effective tool to extend the drug release without additional coating step.

Applicability of near-infrared spectroscopy in the monitoring of film coating and curing process of the prolonged release coated pellets

Although process analytical technology (PAT) guidance has been introduced to the pharmaceutical industry just a decade ago, this innovative approach has already become an important part of efficient pharmaceutical development, manufacturing, and quality assurance. PAT tools are especially important in technologically complex operations which require strict control of critical process parameters and have significant effect on final product quality. Manufacturing of prolonged release film coated pellets is definitely one of such processes. The aim of the present work was to study the applicability of the at-line near-infrared spectroscopy (NIR) approach in the monitoring of pellet film coating and curing steps. Film coated pellets were manufactured by coating the active ingredient containing pellets with film coating based on polymethacrylate polymers (Eudragit® RS/RL). The NIR proved as a useful tool for the monitoring of the curing process since it was able to determine the extent of the curing and hence predict drug release rate by using partial least square (PLS) model. However, such approach also showed a number of limitations, such as low reliability and high susceptibility to pellet moisture content, and was thus not able to predict drug release from pellets with high moisture content. On the other hand, the at-line NIR was capable to predict the thickness of Eudragit® RS/RL film coating in a wide range (up to 40μm) with good accuracy even in the pellets with high moisture content. To sum up, high applicability of the at-line NIR in the monitoring of the prolonged release pellets production was demonstrated in the present study. The present findings may contribute to more efficient and reliable PAT solutions in the manufacturing of prolonged release dosage forms.

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

Antiadherents are used to decrease tackiness of a polymer coating during both processing and subsequent storage. Despite being a common excipient in coating formulae, antiadherents may affect mechanical properties of the coating film as well as drug release from film-coated tablets, but how could addition of antiadherents affect these properties and to what extent and is there a relation between the physical characteristics of the tablet coat and the drug release mechanisms? The aim of this study was to evaluate physical characteristics of films containing different amounts of the antiadherents talc, glyceryl monostearate, and PlasACRYL(TM) T20. Eudragit RL30D and Eudragit RS30D as sustained release polymers and Eudragit FS30D as a delayed release material were used. Polymer films were characterized by tensile testing, differential scanning calorimetry (DSC), microscopic examination, and water content as calculated from loss on drying. The effect of antiadherents on in vitro drug release for the model acetylsalicylic acid tablets coated with Eudragit FS30D was also determined. Increasing talc concentration was found to decrease the ability of the polymer films to resist mechanical stress. In contrast, glyceryl monostearate (GMS) and PlasACRYL produced more elastic films. Talc at concentrations higher than 25% caused negative effects, which make 25% concentration recommended to be used with acrylic polymers. All antiadherents delayed the drug release at all coating levels; hence, different tailoring of drug release may be achieved by adjusting antiadherent concentration with coating level.

Application of active layering and coating techniques in the development of a multiparticulate, controlled release dosage form of a high-dose, highly soluble drug

CONTEXT

The success of the development of controlled release, multilayered, multiparticulate dosage form of a high-dose, highly-soluble drug is dependent upon proper material and processing choices.

OBJECTIVE

To develop a controlled release dosage form of diltiazem hydrochloride using active layering and coating.

METHODS

Active layering was achieved by spraying a drug solution onto sugar cores using polyvinyl alcohol - polyethylene glycol as a binder. Layered pellets with highest loading and lowest binder content were coated using aqueous dispersions of polyvinyl acetate (PVAc). The effects of the plasticizer and curing on drug release were evaluated.

RESULTS AND DISCUSSION

The binder level had no effect on the process efficiency. Drug release from PVAc-coated pellets was slowed by increasing PVAc level. Plasticization slowed drug release in comparison to nonplasticized formulations. Curing affected drug release of nonplasticized formulations only. Protection against humidity was essential in stabilizing drug release under stability study conditions.

CONCLUSION

Materials and process used were suitable to face the challenge posed by the high dose of the water-soluble drug on the success of the formulation. The effects of the plasticizer, curing and ability of packaging to protect against elevated humidity on the performance of the studied system should be considered in development.

Safety and robustness of coated pellets: self-healing film properties and storage stability

PURPOSE

Aim of the study was to verify the safety of chlorpheniramine maleate pellets, coated with blends of poly(vinyl acetate) and poly(vinyl alcohol)-poly(ethylene glycol) graft copolymer. Therefore, the impact of mechanical forces and storage conditions on the drug release was investigated.

RESULTS

Similar release profiles before and after compression of the pellets to tablets underlined the high film robustness. A damage of the film coat with a razor blade resulted in a premature release, but without a burst. After a similar damage with a needle, the release profile remained almost unchanged, which indicated a swelling based self repair mechanism of the film. Additional studies were dedicated to the storage stability at three different conditions. A slightly delayed release was obtained after 6 months storage at 25 degrees C and a marginally accelerated release was measured after storage at elevated temperatures. No drug migration into the coating layer was detected during storage by confocal Raman microscopy. (1)H-NMR analysis during storage demonstrated, that no polymer or drug degradation had occurred and the plasticizer concentration remained constant.

CONCLUSION

The polyvinyl based coating blend for modified release pellets demonstrated a high safety, due to their high robustness and compressibility as well as their satisfying storage stability.

Effect of Eudragit RS 30D and talc powder on verapamil hydrochloride release from beads coated with drug layered matrices

The aim of this study was to investigate the effect of Eudragit RS 30D, talc, and verapamil hydrochloride on dissolution and mechanical properties of beads coated with "drug-layered matrices". This was accomplished with the aid of a three-factor multiple-level factorial design using percent drug release in 1 and 2 h, T(50), tensile strength, brittleness, stiffness and toughness as the responses. Beads were coated in a fluidized-bed coating unit. Surface morphology and mechanical properties were evaluated by surface profilometry and texture analysis, respectively. No cracks, flaws and fissures were observed on the surfaces. The mechanical properties were dependent on the talc/polymer ratio. The release of verapamil from the beads was influenced by matrix components. Increasing the level of both talc and Eudragit decreased the percent drug released from 67% to 4.8% and from 80.7% to 6.7% in 1 and 2 h, respectively, and increased T(50) from 0.8 to 25.7 h. It was concluded that beads could be efficiently coated with "drug-layered matrices". The release of drug, however, depends on a balance between the levels of drug, talc, and polymer, whereby desired dissolution and mechanical properties could be controlled by the talc/polymer ratio and the level of drug loading.

Correlation between the permeability of metoprolol tartrate through plasticized isolated ethylcellulose/hydroxypropyl methylcellulose films and drug release from reservoir pellets

The present study investigates if drug diffusion through plasticized isolated ethylcellulose (EC)/hydroxypropyl methylcellulose (HPMC) films prepared by solvent casting can be used as a tool to develop spray-coated dosage forms. In particular, the importance of the level and type of plasticizers was investigated. The permeability of the model drug metoprolol tartrate through plasticized isolated films could be adjusted by selecting the type and amount of plasticizer in the films due to the different hydrophilicity of the plasticizers. The release of metoprolol tartrate from coated pellets is consistent with the drug diffusion through the films made up of the same polymer blends. This indicated that it is useful to test isolated films for early predictions and for formulation optimization.

A study of the pharmacodynamic differences between immediate and extended release bumetanide formulations

Optimized bumetanide extended (ER) and immediate release (IR) formulations were developed using fluid bed layering and coating techniques. We postulated that the ER bumetanide formulation would have more effective and sustained diuretic and saluretic effects than IR. The diuretic/saluretic effects of both formulations were measured in rabbits (n=8) for two days after dosing with 1mg/kg bumetanide. During the first day, both formulations produced 2-3 times more urine volume and sodium excretion than baseline. In the first 24h, despite less bumetanide excretion from the ER formulation (101+/-13.9microg/kg compared to 146+/-14.6microg/kg for the IR formulation; P<0.04); the ER formulation produced diuresis and natriuresis that was equivalent to that of the IR formulation. In contrast, urine production in the IR formulation group fell below that of placebo controls on day 2. During the second day, the ER formulation was noted to produce persistent bumetanide excretion; the diuretic and natriuretic effects were not statistically significant from baseline control. We speculate that the decrease in response to bumetanide observed especially for the IR formulation during the second day may be due to the activation of compensatory counter-regulatory homeostatic mechanism(s). We conclude that the ER formulation had similar diuretic/saluretic effects but better drug excretion to urine production efficiencies than the IR formulation in the healthy rabbit model. The ER formulation, while providing comparable diuretic/saluretic effect to the IR formulation, offers the advantage of avoiding the initial, rapid and robust diuretic effect experienced with the IR formulations. Taken together, the data provide sufficient basis to warrant further investigation and refinement of our ER bumetanide formulation in humans.