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Ethylcellulose is one of the most commonly used polymers to develop reservoir type extended release multiparticulate dosage forms. For multiparticulate extended release dosage forms, the drug release is typically governed by the properties of the barrier membrane coating. The ICH Pharmaceutical Development Guideline (ICH Q8) requires an understanding of the influence of critical material attributes and critical process parameters on the drug release of a pharmaceutical product. Using this understanding, it is possible to develop robust formulations with consistent drug release characteristics. Critical material attributes for ethylcellulose were evaluated, and polymer molecular weight variation (viscosity) was considered to be the most critical attribute that can impact drug release. To investigate the effect of viscosity variation within the manufacturer's specifications of ethylcellulose, extended release multiparticulate formulations of two model drugs, metoprolol tartrate and acetaminophen, were developed using ETHOCEL™ as the rate controlling polymer. Quality by Design (QbD) samples of ETHOCEL Std. 10, 20, and 100 Premium grades representing the low, medium, and high molecular weight (viscosity) material were organically coated onto drug layered multiparticulates to a 15% weight gain (WG). The drug release was found to be similar (f 2 > 50) for both metoprolol tartrate and acetaminophen multiparticulates at different coating weight gains of ethylcellulose, highlighting consistent and robust drug release performance. The use of ETHOCEL QbD samples also serves as a means to develop multiparticulate dosage formulations according to regulatory guidelines.

Acceptability of medicines is critical for effective pharmacotherapy. The aim of this study was to investigate the oral sensory properties of tablet coatings to determine how mouthfeel can improve acceptability. A randomised double-blind study was performed in 84 adult volunteers (51% ≥55 years). Each participant received 4 placebo tablets (3 coated and 1 uncoated) to evaluate (i) ease of swallowing and (ii) palatability. Visual analogue scales (VAS) were used to capture sensory parameters. Acceptability was assessed using the following parameters: ease of swallowing; amount of water taken with the tablet; rank order of preference; roughness; adhesiveness and slipperiness. Ease of swallowing was determined to be the most sensitive measure of acceptance. The best coating was the one that was reported to be the most slippery and smooth. The presence of a coating improved ease of swallowing, mouthfeel and overall palatability. This study demonstrates that slippery coatings improve acceptability of tablets. The study also demonstrates the value of VAS to measure the sensory attributes of coated tablets.

The crystallization kinetics of the monodisperse n-alkane C98H198, growing as extended-chain lamellae from the melt, have been measured as part of a wider programme on these novel model systems for polymeric materials. Crystal growth rates decrease linearly, by a factor of 30, over the temperature range of 113.5–114.9°C, an interval which encompasses a significant change in habit from individual through parallel-stacked lamellae to a type of coarse spherulite. The data differ considerably in character from those reported previously for extended chain crystallization of n-C198H398 but are comparable to earlier studies of purified n-C94H190 and are sensibly linear with supercooling as proposed in Hoffman's theory of extended-chain crystallization.

The morphology of woven polypropylene cloth compactions, prepared at a series of temperatures, has been examined by electron microscopy following permanganic etching. With increasing temperature, the interior structure of the fibres is seen to undergo progressively greater melting and recrystallization in the form of shish-kebab structures while the volume of melt surrounding the fibres increases. The regions of recrystallized extra-fibrillar melt show effects of flow-induced orientation in the form of row structures. The presence of boundaries persisting where recrystallization fronts have met is interpreted as an effect of segregation of low molecular weight material.

In this paper we describe the hot compaction of woven polypropylene (PP) tapes. It is shown that under suitable conditions of temperature and pressure, successful compaction is achieved by selective melting of the PP tapes. Mechanical measurements, combined with morphological studies, show that good tape to tape bonding, and good interlayer bonding, are achieved using an optimum compaction temperature of around 182 °C, while retaining a significant proportion of the original PP structure. Differential scanning calorimetry studies have shown that the compaction temperatures employed to produce a homogeneous coherent material have a significant annealing affect on the crystalline structure of the original drawn tapes, with a large change in the crystal size and a small increase in overall crystallinity (accompanied by a small increase in sample density). The mechanical properties of the compacted PP sheets show a combination of low density and good stiffness and strength.