Solubility and Dissolution Rates in Reactive Media

Higuchi, William I.; Nelson, Eino; Wagner, John G.

doi:10.1002/jps.2600530321

Cited by 30 publications

(20 citation statements)

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“…Another assumption was that there was no agglomeration of crystal particles or breakage of large crystals from shear forces during stirring. All these assumptions allow expressing the rate of crystal growth in a simpler form [26], as follows:…”

Section: Crystal Growthmentioning

confidence: 99%

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Comprehensive kinetic model for the dissolution, reaction, and crystallization processes involved in the synthesis of aspirin

Joiner

Billeter

McNally

et al. 2014

Journal of Chemometrics

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Kinetic modeling of batch reactions monitored by in situ spectroscopy has been shown to be a helpful method for developing a complete understanding of reaction systems. Much work has been carried out to demonstrate the ability to model dissolution, reaction, and crystallization processes separately; however, little has been performed in terms of combining all of these into one comprehensive kinetic model. This paper demonstrates the integration of models of dissolution, temperature-dependent solubility, and unseeded crystallization driven by cooling into a comprehensive kinetic model describing the evolution of a slurry reaction monitored by in situ attenuated total reflectance ultraviolet-visible spectroscopy. The model estimates changes in the volume of the dissolved fraction of the slurry by use of the partial molar volume of the dissolved species that change during the course of reagent addition, dissolution, reaction, and crystallization. The comprehensive model accurately estimates concentration profiles of dissolved and undissolved components of the slurry and, thereby, the degree of undersaturation and supersaturation necessary for estimation of the rates of dissolution and crystallization. Results were validated across two subsequent batches via offline high-performance liquid chromatography measurements.

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Section: Crystal Growthmentioning

confidence: 99%

“…The rate of dissolution [26,27] for a solute s, defined as r d,s , can be expressed in a similar way to the formulation of the rate of crystal growth presented in Equation (13):…”

Section: Dissolutionmentioning

confidence: 99%

Comprehensive kinetic model for the dissolution, reaction, and crystallization processes involved in the synthesis of aspirin

Joiner

Billeter

McNally

et al. 2014

Journal of Chemometrics

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“…The dissolution rate of a sparingly soluble weak electrolyte drug is proportional to the total solubility (6,8) where the total solubility, S total , for a weak acid drug compound, RCO 2 H, in the microenvironment is defined by ] o is the hydrogen ion concentration at the solid-liquid interface. Equation 8 predicts that the total solubility will decrease when pH o > pK a drug and increase when pH o < pK a drug .…”

Section: Total Solubility and Relative Dissolution Rate For A Weak Acmentioning

confidence: 99%

“…Buffered aqueous medium affects the dissolution rate of a sparingly soluble weak acid or weak base drug due to ionic interactions between the drug and the buffer species in the microenvironment at the solid-liquid interface (5)(6)(7)(8)(9)(10)(11)(12)(13)(14); however, the influence of the buffer can be affected by the self-buffering capacity of the dissolved drug in the microenvironment. The extent to which the buffer influences dissolution rate depends on the ionization constants of the buffer and drug, total molar concentration of the buffer and buffer capacity, concentration of buffer species reacting with the drug compound, total drug solubility, and solubility of the un-ionized form of the drug compound.…”

Section: Introductionmentioning

confidence: 99%

Formulating Buffered Dissolution Media for Sparingly Soluble Weak Acid and Weak Base Drug Compounds Based on Microenvironmental pHo Considerations

Stippler¹,

Romero²,

Mauger³

2014

Dissolution Technol.

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The theoretical framework for dissolution of weak acid and weak base drug compounds in buffered media is well established. Therefore, this article is intended to provide a review of this framework and apply it to formulate buffered dissolution media based on ionic equilibrium conditions within the diffusion layer at the solid-liquid interface. The pH o in the microenvironment is identified as a singularly important parameter that reflects ionic interactions between dissolving drug and buffer at the solid-liquid interface. This article is focused on (1) formulating buffered dissolution media based on ionic equilibrium conditions at the solid-liquid interface, (2) identifying key physicochemical parameters for both drug and buffer that are relevant to buffer formulation, and (3) providing experimental and calculation-based methods to estimate the pH o at the solid-liquid interface. A shift in emphasis from relying solely on bulk buffer pH properties forms a basis for formulating buffered dissolution media and also provides insight into the physicochemical factors that affect the dissolution rate of the drug compound.

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“…From these experiments it was concluded that the release process was regulated at least in part by natural convection. This conclusion was based on differences between theoretically predicted ((E)SCRD-theory; Higuchi et al, 1958;Higuchi et al, 1964;Mooney et al, 1981a and1981b) and our experimental!y obtained data.…”

Section: Introductionmentioning

confidence: 95%

Drug release from non-aqueous suspensions. II. The release of methylxanthines from paraffin suspensions

Fokkens¹,

Blaey²

1984

International Journal of Pharmaceutics

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SummaryThe release of 3 methylxanthines, i.e. caffeine, theobromine and theophylline, from suspensions in liquid paraffin to an aqueous phase was determined in an in vitro apparatus. The release rates were determined as a function of the pii of the aqueous phase. It was proved that the release process was natural convection-regulated. The release rate per unit area was correlated to the solubility of the drug to the power 1 .l 1. In case of the release of theophylfine anhydrate from the suspensions a cake of theophylline hydrate was forrtied at the interface paraffim/buffer, which resulted in a decreasing release rate. The formation of the cake was mostly completed within 20 min, whereafter the release rate was exactly the same as the release rate of theophylline hydrate.

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Solubility and Dissolution Rates in Reactive Media

Cited by 30 publications

References 1 publication

Comprehensive kinetic model for the dissolution, reaction, and crystallization processes involved in the synthesis of aspirin

Comprehensive kinetic model for the dissolution, reaction, and crystallization processes involved in the synthesis of aspirin

Formulating Buffered Dissolution Media for Sparingly Soluble Weak Acid and Weak Base Drug Compounds Based on Microenvironmental pHo Considerations

Drug release from non-aqueous suspensions. II. The release of methylxanthines from paraffin suspensions

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