Determination of Inherent Dissolution Performance of Drug Substances

The dissolution behavior of novel active pharmaceutical ingredients (API) is a crucial parameter in drug formulation since it frequently affects the drug release. Generally, a distinction is made between surface-reaction- and diffusion-controlled drug release. Therefore, dissolution studies such as the intrinsic dissolution test defined in the pharmacopeia have been performed for many years. In order to overcome the disadvantages of the common intrinsic dissolution test, a new experimental setup was developed within this study. Specifically, a flow channel was designed and tested for measuring the mass transfer from a flat, solid surface dissolving into a fluid flowing over the surface with well-defined flow conditions. A mathematical model was developed that distinguishes between surface-reaction- and diffusion-limited drug release based on experimental data. Three different drugs—benzocaine, theophylline and griseofulvin—were used to investigate the mass flux during dissolution due to surface reaction, diffusion and convection kinetics. This new technique shows potential to be a valuable tool for the identification of formulation strategies.

Download Full-text

Reaction-Diffusion Systems: Self-Balancing Diffusion and the Use of the Extent of Reaction as a Descriptor of Reaction Kinetics

10.26434/chemrxiv.11431878.v1 ◽

2019 ◽

Author(s):

Miloslav Pekař

Keyword(s):

Reaction Kinetics ◽

Reaction Diffusion ◽

Reaction Diffusion Systems ◽

Diffusion Systems ◽

And Diffusion ◽

Reaction And Diffusion

Self-balancing diffusion is a concept which restricts the introduction of extents of reactions. This concept is analyzed in detail for mass- and molar-based balances of reaction-diffusion mixtures, in relation to non-self-balancing cases, and with respect to its practical consequences. A note on a recent generalization of the concept of reaction and diffusion extents is also included.<br>

Download Full-text

Thermopower method for detecting the ferrite-austenite transition: applications to surface reaction and diffusion

Archiv für das Eisenhüttenwesen ◽

10.1002/srin.198104932 ◽

1981 ◽

Vol 52 (7) ◽

pp. 265-269

Author(s):

Károly Lázár ◽

András Sütö ◽

Lajos Varga

Keyword(s):

Surface Reaction ◽

And Diffusion ◽

Reaction And Diffusion

Download Full-text

Fabrication and dissolution behavior of hollow hydroxyapatite microspheres intended for controlled drug release

Materials Research Bulletin ◽

10.1016/j.materresbull.2009.06.015 ◽

2009 ◽

Vol 44 (10) ◽

pp. 1939-1942 ◽

Cited By ~ 17

Author(s):

Ruixue Sun ◽

Kezheng Chen ◽

Yupeng Lu

Keyword(s):

Drug Release ◽

Controlled Drug Release ◽

Dissolution Behavior

Download Full-text

Analogy Between Transient Heat Conduction and Dissolution of Solid Particles in Liquids Based on the Shrinking Core Model

Volume 2: Heat Transfer Equipment; Heat Transfer in Multiphase Systems; Heat Transfer Under Extreme Conditions; Nanoscale Transport Phenomena; Theory and Fundamental Research in Heat Transfer; Thermophysical Properties; Transport Phenomena in Materials Processing and Manufacturing ◽

10.1115/ht2017-5009 ◽

2017 ◽

Author(s):

Qin Ma

Keyword(s):

Heat Conduction ◽

Drug Release ◽

Numerical Solutions ◽

Transient Heat Conduction ◽

Controlled Drug Release ◽

Solid Particles ◽

Core Model ◽

Dissolution Behavior ◽

Shrinking Core Model ◽

Shrinking Core

In this study, the analogy between transient heat conduction and mass transfer is applied to investigate the dissolution behavior of solid particles in liquids, particularly, for the transport phenomenon associated with the controlled drug release process. Mathematical modeling is established assuming the shrinking core is solely caused by the diffusion mechanism. The transport governing equations for the dissolution process of controlled drug release are compared with the transient heat conduction differential equations. Analogous quantities, certain analytical solutions and numerical solutions for complex geometry are obtained to demonstrate the dissolution behavior of this specific type of solid particles in liquids based on the proposed shrinking core model. It is found that the shape of the drug capsule plays an important role for effective and timely release of drug content after intake. Among the three shapes investigated herein, sphere, cube and cuboid, we conclude that the drug concentration in a cuboid shaped drug head depletes the quickest whereas the spherical shaped head dissolves the slowest.

Download Full-text

The Kinetics of Crystal Growth in Barium Sulfate Precipitation. III. Mixed Surface Reaction and Diffusion Controlled Rate of Growth.

Acta Chemica Scandinavica ◽

10.3891/acta.chem.scand.13-1680 ◽

1959 ◽

Vol 13 ◽

pp. 1680-1686 ◽

Cited By ~ 8

Author(s):

Arne E. Nielsen ◽

Margareta Zackrisson ◽

Sigvard Eriksson ◽

C.-G. Hedén ◽

B. Malmgren ◽

...

Keyword(s):

Crystal Growth ◽

Barium Sulfate ◽

Surface Reaction ◽

Rate Of Growth ◽

Diffusion Controlled ◽

Kinetics Of ◽

And Diffusion ◽

Kinetics Of Crystal Growth ◽

Reaction And Diffusion

Download Full-text

Biological self-organisation and pattern formation by way of microtubule reaction-diffusion processes

Advances in Complex Systems ◽

10.1142/s0219525999000138 ◽

1999 ◽

Vol 02 (03) ◽

pp. 221-276 ◽

Cited By ~ 8

Author(s):

James Tabony ◽

Laurent Vuillard ◽

Cyril Papaseit

Keyword(s):

Pattern Formation ◽

Diffusion Processes ◽

Reaction Diffusion ◽

Underlying Process ◽

Self Organisation ◽

And Diffusion ◽

Reaction And Diffusion

Chemically dissipative or Turing processes, have been predicted by theoreticians as a way by which an initially homogenous solution of chemicals or biochemicals can spontaneously self-organise and give rise to a macroscopic pattern by way of a combination of reaction and diffusion. They have been advanced as a possible underlying process for biological self-organisation and pattern formation. Until now, there have been no examples of in vitro biological substances showing this type of behaviour. Evidence is presented that microtubule solutions in vitro self-organise in this manner and that similar processes may occur in vivo during embryogenesis.

Download Full-text