Polysorbate 20 as a drug release regulator in ethyl cellulose film coatings

Sustained Release Drug Delivery Applications of Polyurethanes

Since their introduction over 50 years ago, polyurethanes have been applied to nearly every industry. This review describes applications of polyurethanes to the development of modified release drug delivery. Although drug delivery research leveraging polyurethanes has been ongoing for decades, there has been renewed and substantial interest in the field in recent years. The chemistry of polyurethanes and the mechanisms of drug release from sustained release dosage forms are briefly reviewed. Studies to assess the impact of intrinsic drug properties on release from polyurethane-based formulations are considered. The impact of hydrophilic water swelling polyurethanes on drug diffusivity and release rate is discussed. The role of pore formers in modulating drug release rate is examined. Finally, the value of assessing mechanical properties of the dosage form and approaches taken in the literature are described.

Monitoring of dissolution induced changes in film coat composition by 1H NMR spectroscopy and SEM

In our study we investigated the release mechanisms of coated oral dosage forms more deeply. The aim of the study was to monitor the buffer induced leaching out of water soluble compounds from Kollicoat SR films and to relate this process to the film properties and the release kinetics. Propranolol HCl tablets were coated with different amounts and ratios of polyvinyl acetate (Kollicoat SR) and poly(vinyl alcohol)-poly(ethylene glycol)-graft-copolymer (Kollicoat IR). Polyvinyl pyrrolidone (Kollidon 30) was added as a second water soluble polymer and triacetin as a plasticizer. In addition to kinetics of the drug release, the films were studied by SEM and 1H NMR spectroscopy. SEM micrographs revealed morphological changes of the tablet surface that were related to an alteration in film coat composition. The described 1H NMR method provided the opportunity to quantify the leaching of Kollicoat IR, Kollidon 30 and triacetin. Drug release kinetics were related to dissolution induced changes in coating composition. Permeability of the film coat increased, when about 90% of the water soluble polymers and plasticizer triacetin were leached out of the film coat.

Influence of type and level of water-soluble additives on drug release and surface and mechanical properties of Surelease films

Ethylcellulose in combination with water-soluble additives has been used in the development of microporous membrane-coated dosage forms. In the present study, application of three types of water-soluble additives, namely polyethylene glycols (PEG 400, 3350, and 8000), maltodextrins (Maltrin M150, M100, and M040 in the order of lower to higher average polymer size and molecular weight; dextrose equivalence 16.9, 11.1, and 4.8, respectively), and xylitol, as porosity modifiers in the films of a commercially available aqueous ethylcellulose dispersion (Surelease/E-7-7060 plasticized with glyceryl tricaprylate/caprate) was investigated. The effect of type and level of these additives on drug release characteristics and surface and mechanical properties of the polymeric films was studied. Each additive was incorporated at 20 and 30% levels in the polymeric dispersion based on its solids content. Ibuprofen tablets were coated using the polymeric dispersion with and without additive at 3% w/w coat level in a fluid-bed equipment. The coated tablets were evaluated for their drug release rate, coat reflectivity (gloss), Brinell hardness, and elastic modulus. Differential scanning calorimetric analysis of the films was performed to determine the physico-chemical changes in the applied film-coats. The rate of drug release, hence film porosity, was observed to be dependent on the type and level of the additive added. The molecular weight of the additive and its concentration in the polymeric dispersion had significant influence on the rate of drug release, hardness, and elasticity of the film-coats.

Study of drug release from pellets coated with Surelease containing hydroxypropylmethylcellulose

The release of metoclopramide hydrochloride (a very water soluble cationic drug) and diclofenac sodium (a sparingly soluble anionic drug) from pellets coated with Surelease containing hydroxypropylmethylcellulose (HPMC) at different coating loads was investigated. The release rates of either drug at each coating composition decreased as the coating load increased. Inclusion of HPMC E15 increased the release rates of both drugs compared to pellets coated only with Surelease. This was thought to be due to the leakage of the soluble part of the film (HPMC E15) during dissolution, which left pores for drug release. The Surelease:HPMC E15 ratio had a major role in the release rates of drugs. Addition of HPMC E15 into Surelease did not change the release mechanism for metoclopramide hydrochloride (the mean value of n approximately 0.57) from that of Surelease alone, and diffusion remained the main mechanism controlling the release. However, the release exponent (approximately 1.28) increased for diclofenac sodium on addition of HPMC E15, indicating a dissolution-controlled mechanism. Despite its lower water solubility, diclofenac sodium was released slightly faster than metoclopramide hydrochloride from pellets coated with Surelease containing HPMC E15 at equivalent coating loads.

Influence of surfactants in aqueous-based polymeric dispersions on the thermomechanical and adhesive properties of acrylic films

Good adhesion between a polymeric film and the surface of a solid substrate is critical to the performance of coated pharmaceutical products. Previous research has shown that tablet wettability by an organic-based cellulosic solution could predict the extent of film-tablet adhesion. Using an aqueous-based acrylic polymeric dispersion, the current study investigated the relationship between film adhesion and tablet wettability. Up to 10% (w/w based on dry polymer weight) polysorbate 80 or sorbitan monooleate was incorporated into the film-coating formulations. While the contact angle between the polymeric dispersion and the tablet surface was dependent on the type and concentration of surfactants added to the coating formulation, no correlation between tablet wettability and polymer adhesion could be established. The addition of surfactants to formulations containing the hydrophobic plasticizer tributyl citrate (TBC) caused lowering of the glass transition temperature of the polymer. Increased force of adhesion, elongation at adhesive failure, and adhesive toughness, however, were noted only in the TBC-plasticized films containing polysorbate 80. These findings demonstrate that our understanding of the mechanisms involved in film-tablet adhesion is still quite limited.

Effect of polysorbates on atenolol release from film-coated tablets

The effects of different concentrations of various polysorbates on the release rate of atenolol from film-coated tablets were evaluated. The release profile of atenolol showed that increasing the concentration of polysorbate resulted in an increase in the release rate of atenolol. The type of polysorbate had less effect on the release rate of atenolol. This study revealed that the release kinetic of atenolol from these film-coated tablets was a function of polysorbate concentration. Correlation coefficients of kinetic models could not solely determine the suitability of the models; the sum of the least square of differences also should be calculated when different kinetic models have similar correlation coefficients.