A dynamic system for the simulation of fasting luminal pH-gradients using hydrogen carbonate buffers for dissolution testing of ionisable compounds.

Recent interest in the development of drug particle-laden strip-films suggests the need for establishing standard regulatory tests for their dissolution. In this work, we consider the dissolution testing of griseofulvin (GF) particles, a poorly water-soluble compound, incorporated into a strip-film dosage form. The basket apparatus (USP I) and the flow-through cell dissolution apparatus (USP IV) were employed using 0.54% sodium dodecyl sulfate as the dissolution medium as per USP standard. Different rotational speeds and dissolution volumes were tested for the basket method while different cell patterns/strip-film position and dissolution media flow rate were tested using the flow-through cell dissolution method. The USP I was not able to discriminate dissolution of GF particles with respect to particle size. On the other hand, in the USP IV, GF nanoparticles incorporated in strip-films exhibited enhancement in dissolution rates and dissolution extent compared with GF microparticles incorporated in strip-films. Within the range of patterns and flow rates used, the optimal discrimination behavior was obtained when the strip-film was layered between glass beads and a flow rate of 16 ml/min was used. These results demonstrate the superior discriminatory power of the USP IV and suggest that it could be employed as a testing device in the development of strip-films containing drug nanoparticles.

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Using USP I and USP IV for Discriminating Dissolution Rates of Nano- and Microparticle-Loaded Pharmaceutical Strip-Films

Computational fluid dynamics (CFD) insights into agitation stress methods in biopharmaceutical development.

Industry's View on Using Quality Control, Biorelevant, and Clinically Relevant Dissolution Tests for Pharmaceutical Development, Registration, and Commercialization.

The bicarbonate buffer is considered as the most biorelevant buffer system for the simulation of intestinal conditions. However, its use in dissolution testing of solid oral dosage forms is very limited. The reason for this is the thermodynamic instability of the solution containing hydrogen carbonate ions and carbonic acid. The spontaneous loss of carbon dioxide (CO2) from the solution results in an uncontrolled increase of the pH. In order to maintain the pH on the desired level, either a CO2 loss must be completely avoided or the escaped CO2 has to be replaced by quantitative substitution, i.e. feeding the solution with the respective amount of gas, which re-acidifies the buffer after dissociation. The present work aimed at the development of a device enabling an automatic pH monitoring and regulation of hydrogen carbonate buffers during dissolution tests.

An Automated System for Monitoring and Regulating the pH of Bicarbonate Buffers

Velocity profiles and shear strain rate variability in the USP Dissolution Testing Apparatus 2 at different impeller agitation speeds

Self-Repairable, Recyclable and Heat-Resistant Polyurethane for High-Performance Automobile Tires

A Novel Off-Center Paddle Impeller (OPI) Dissolution Testing System for Reproducible Dissolution Testing of Solid Dosage Forms

Elastomeric damping materials are essential in modern life. Apart from natural rubber, conventional elastomers are mostly based on petroleum-based sources. Moreover, elastomers exhibit excellent damping properties in the glass transition region, the glass transition temperature (Tg) of elastomers is lower than room temperature, resulting in poor damping properties at room temperature. However, because of limited and unsustainable petrochemical resources and environmental pollution, sustainable development and green environmental protection have become important principles in the design of damping materials, and most damping materials are used at room temperature. Therefore, designing bio-based materials with high damping properties at room temperature to replace conventional cross-linked rubber materials is crucial. Herein, we prepared bio-based millable polyurethane (bio-MPU)/hindered phenol 3,9-bis-{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl-)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro (Wang et al., 2016; Wang et al., 2016) [5,5]-undecane (AO-80) composites to overcome the challenge of sustainable development and high damping properties at room temperature. Bio-MPU samples with high Tg were synthesized from bio-based modified polylactic acid-based polyols, 4, 4′-diphenylmethane diisocyanate, and unsaturated chain extender 3-allyloxy-1, 2-propanediol. AO-80 was mixed with bio-MPU to further increase the Tg and enhance the damping properties of the bio-MPU/AO-80 composites. The properties of the bio-MPUs and bio-MPU/AO-80 composites were systematically evaluated. This study proposes a strategy to design high damping properties from bio-based raw materials and reduce our dependence on fossil resources. 

Yimin Wang

Papers

Velocity profiles and shear strain rate variability in the USP Dissolution Testing Apparatus 2 at different impeller agitation speeds

Self-Repairable, Recyclable and Heat-Resistant Polyurethane for High-Performance Automobile Tires

A Novel Off-Center Paddle Impeller (OPI) Dissolution Testing System for Reproducible Dissolution Testing of Solid Dosage Forms

Bio-based polyurethane/hindered phenol AO-80 composites for room temperature high damping properties

Experimental study of the heat transfer characteristics of single geothermal fracture at different reservoir temperature and in situ stress conditions