Influence of ibuprofen as a solid-state plasticizer in Eudragit RS 30 D on the physicochemical properties of coated beads

Plasticization and antiplasticization of an acrylic pressure sensitive adhesive by ibuprofen and their effect on the adhesion properties

In transdermal patches, an unpredictable alteration of the mechanical behavior of the pressure sensitive adhesive (PSA) can occur if a drug is added. In the present study, the suitability of Dynamic Mechanical Analysis (DMA)/Dynamic Mechanical Thermal Analysis (DMTA) as methodologies to detect the change in adhesion properties caused by the addition of an API was examined. With DMA/DMTA, time- and temperature-dependent viscoelastic properties were determined. Tack and shear adhesion of blends of the acrylic adhesive DuroTak® 87-4287 and ibuprofen at increasing concentrations were investigated. Interestingly, the probe tack test showed highest values at 1% ibuprofen concentration in the PSA and decreasing values with increasing ibuprofen concentrations. The shear adhesion of the PSA was decreased at all investigated ibuprofen concentrations. With DMA/DMTA, it could be demonstrated that antiplasticization and plasticization are responsible for the change in tack. The main reason for the decrease in shear adhesion is a shift of the Tg to lower temperatures, while antiplasticization only has a marginal effect. The term "antiplasticizing space" was introduced because antiplasticization depends on time, temperature, stress, strain, and API concentration. In general, this antiplasticizing space can have an impact on processing, stability, and in vivo behavior of API/polymer blends in drug formulations.

Amorphous solid dispersions and nano-crystal technologies for poorly water-soluble drug delivery

Poor water-solubility is a common characteristic of drug candidates in pharmaceutical development pipelines today. Various processes have been developed to increase the solubility, dissolution rate and bioavailability of these active ingredients belonging to BCS II and IV classifications. Over the last decade, nano-crystal delivery forms and amorphous solid dispersions have become well established in commercially available products and industry literature. This article is a comparative analysis of these two methodologies primarily for orally delivered medicaments. The thermodynamic and kinetic theories relative to these technologies are presented along with marketed product evaluations and a survey of commercial relevant scientific literature.

Drugs acting as plasticizers in polymeric systems: A quantitative treatment

The objective of the present study was to investigate and quantify the effects of ibuprofen, chlorpheniramine maleate and metoprolol tartrate on the thermal, mechanical and diffusional properties of polyacrylate-based films. Thin drug-containing films were prepared from organic Eudragit RS solutions and physicochemically characterized with respect to their glass transition temperature, mechanical properties and drug release kinetics in phosphate buffer pH 7.4. The apparent diffusion coefficient of the drug within the polymeric systems was determined by fitting an adequate solution of Fick's second law of diffusion to the experimentally determined release profiles. Importantly, the glass transition temperature of the films significantly decreased with increasing initial drug content, whereas the film flexibility and drug release rate increased. This clearly indicates that the three drugs act as efficient plasticizers for Eudragit RS. Interestingly, the mathematical analysis revealed that drug release was primarily controlled by diffusion. An increase in the initial drug content resulted in increased drug diffusivities and, thus, accelerated (absolute and relative) drug release rates. Importantly, quantitative relationships could be established between the drug diffusivity and the initial drug content. Based on this knowledge, the effects of the films' composition and thickness on the resulting drug release kinetics (also from coated solid dosage forms) can be predicted in a quantitative way.