Hydrodynamics of Dissolution in a Newtonian and a Non-Newtonian Solution

Chang, Shu-Hwa; Parrott, Eugene L.

doi:10.3109/03639049109074389

Cited by 3 publications

(5 citation statements)

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“…Einflüsse der Kristallstruktur (Aufbau, Fehlstellen) und gegebenenfalls der Polymorphie bilden die Entropiebilanz (Entropiezuwachs bei Lösung des Kristallverbandes). Auf k T wirken hingegen beispielsweise die kinematische Viskosität des Fluids (Chang et al 1991)…”

Section: Reaktionskontrollierte Oder Transportkontrollierte Lösungsge...unclassified

“…Signifikanter wirkt sich die Viskositätsänderung auf die Strömungscharakteristik aus. Chang et al (1991) beobachteten mit einer bestimmten Art der Viskositätserhöhung, herbeigeführt durch Makromoleküle (Guar), eine Alteration der Strömungscharakteristik des Mediums bei Lösungsgeschwindigkeits-Studien an Benzoesäure. Ein solcher Effekt konnte jedoch nicht beobachtet werden, wenn dieselbe Viskosität im Medium mit Propylenglykol eingestellt wurde.…”

Section: Kinematische Viskosität (ν)unclassified

“…62 Die den Massentransfer charakterisierende Sherwood-Zahl (Sh) ist in den meisten Massentransfer-Relationen in stärkerem Maße von der Reynolds-Gruppe (Re) abhängig als von der Schmidt-Gruppe (Sc) (Cussler 1997;Levich 1962;Barker et al 1960;Harriott 1962;Chang et al 1991;Dreybrodt et al 1991;Lehmkuhl et al 1971). Die Schmidt-Gruppe (Sc) charakterisiert den diffusiven Einfluß auf den Massentransfer, die Reynolds-Gruppe (Re) den konvektiven, also den durch die Hydrodynamik bestimmten.…”

Section: Reunclassified

“…Es handelt sich hier um ein Problem der experimentellen Empfindlichkeit und Differenzierbarkeit (vgl. Chang et al 1991;Hamlin et al 1962).…”

Section: Gründe Für Das Vorherrschen Unterschiedlicher Sichtweisenunclassified

“…mit 0.833 undChang et al (1991) mit 0.89. Da die genannten Autoren in vollturbulenten Systemen arbeiteten, wird ein Exponent nahe dem Wert 1 verständlich.…”

unclassified

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Hydrodynamik und Lösungsgeschwindigkeit - Untersuchungen zum Einfluss der Hydrodynamik auf die Lösungsgeschwindigkeit schwer wasserlöslicher Arzneistoffe (rev. Fassung 2022) : Hydrodynamics and Dissolution - Influence of Hydrodynamics on Dissolution Rate of Poorly Soluble Drugs (rev. version 2022)

Diebold

2023

Preprint

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The objectives of the present study were to (1) examine both the hydrodynamics of compendial in vitro dissolution test apparatus as well as the respective in vivo gastrointestinal hydrodynamics in dogs, (2) describe the influence of hydrodynamics on the dissolution rates of poorly soluble drugs and (3) to develop a hydrodynamic based model to a priori predict dissolution rates of poorly soluble compounds. Hydrodynamics of compendial dissolution test apparatus (paddle and basket) were directly characterized by means of an ultrasound pulse echo method. Fluid velocities within the dissolution vessels correlated well and in a linear manner with the rotational speed (rpm) of both the paddle and basket test apparatus, respectively. Thus, based on this correlation, it was possible to calculate velocities of the dissolution media at any rotational speed. Fluid velocities were determined using the basket method to range between 0.3 and 5 cm/s (25 to 200 rpm) and for the paddle method to range between 1.8 and 37 cm/s. These fluid velocity data, determined empirically here for the first time in compendial dissolution vessels, are a prerequisite to forecast drug substance dissolution rates in vitro. In order to calculate such mass transfer rates the so called "Kombinations-Modell" was developed. This model is based on the convective diffusion theory by V.G. Levich. Here, we applied it on coarse and micronized felodipine powders as drug substance models as well as on oxygen as a model / vector to study hydrodynamics independent of chemical nature or state of aggregation. As a result, predicted dissolution rate data, calculated by means of the combination model, were found to correspond well with the respective dissolution rates determined by experiment. As expected, hydrodynamics did not discriminate between different states of aggregation of the two model compounds oxygen (gas) and felodipine (solid). Using the paddle method Reynolds numbers from Re=2292 to Re=31025 were calculated. In contrast, Reynolds numbers determined using the basket apparatus ranged from Re=231 to Re=4541. With respect to changes in hydrodynamic conditions particles of coarse grade felodipine were found to be more sensitive than micronized material of the same chemical species. A scintigraphic method was established to modulate intestinal hydrodynamics and to subsequently study gastric emptying and intestinal transit of caloric and non-caloric fluids in labradors. For orally administered solutions time needed for total gastric emptying (GE>95%) was found to depend on both volume and caloric content. GE>95% for 200 ml of 20 % aqueous glucose solution differed significantly (278 min.) from GE>95% for the same volume of 0.9 % sodium chloride solution (97 min.). After administration of 20 % glucose solution the mean duodeno-jejunal transit rate (MTR) was determined to be 2.7 cm/min. This was significantly different from measured MTR after administration of the same volume of 0.9 % sodium chloride solution (1.1 cm/min.). However, duodeno-jejunal transit itself was found not to correlate with gastric emptying. Gastro-intestinal flow rates (= flow influenced also by gastric emptying) were determined using an aspiration method. After administration of 200 ml of 20 % glucose solution gastro-intestinal flow rates reached (short time) maxima from 20 to 60 ml/min. (median: 8.3 ml/min.). In contrast, gastro-intestinal flow rates were found to be significantly higher following administration of 200 ml of 0.9 % sodium chloride solution, exhibiting (short lasting) maxima of up to 100 ml/min. (median: 35.0 ml/min.). Luminal dissolution rate of felodipine was found to be greater following coadministration of hypertonic (!) glucose than following coadministration of 0.9 % saline. This result correlated well with an increased intestinal fluid volume (collected 76 cm distal to the pylorus) following oral administration of 20 % glucose solution.

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Section: Reaktionskontrollierte Oder Transportkontrollierte Lösungsge...unclassified

Section: Kinematische Viskosität (ν)unclassified

Section: Reunclassified

“…Es handelt sich hier um ein Problem der experimentellen Empfindlichkeit und Differenzierbarkeit (vgl. Chang et al 1991;Hamlin et al 1962).…”

Section: Gründe Für Das Vorherrschen Unterschiedlicher Sichtweisenunclassified

“…mit 0.833 undChang et al (1991) mit 0.89. Da die genannten Autoren in vollturbulenten Systemen arbeiteten, wird ein Exponent nahe dem Wert 1 verständlich.…”

unclassified

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Hydrodynamik und Lösungsgeschwindigkeit - Untersuchungen zum Einfluss der Hydrodynamik auf die Lösungsgeschwindigkeit schwer wasserlöslicher Arzneistoffe (rev. Fassung 2022) : Hydrodynamics and Dissolution - Influence of Hydrodynamics on Dissolution Rate of Poorly Soluble Drugs (rev. version 2022)

Diebold

2023

Preprint

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Comparison of guar gum from different sources for the preparation of prolonged-release or colon-specific dosage forms

Acartürk

Celkan

2009

Pharmaceutical Development and Technology

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The aim of the present study was to compare some physicochemical properties of guar gum samples from different sources and thus to investigate the suitability of these samples for the formulation of either prolonged-release or colon-specific dosage forms. Twelve different guar gum samples from India, Pakistan and the USA were used. Theophylline was chosen as a model drug. The flow type of the guar gum samples was determined as pseudoplastic. The viscosity and the particle size of the guar gum samples were found to be the main parameters which could affect the drug release from matrix tablets. All of the guar gum samples are suitable for use in the preparation of prolonged-release matrix tablets. But, three of them, obtained from India and the USA, may be potentially the most suitable guar gum samples for the preparation of colon-specific dosage forms.

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Physiological Parameters Relevant to Dissolution Testing

Diebold¹

2005

Pharmaceutical Dissolution Testing

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Hydrodynamics of Dissolution in a Newtonian and a Non-Newtonian Solution

Cited by 3 publications

References 10 publications

Comparison of guar gum from different sources for the preparation of prolonged-release or colon-specific dosage forms

Physiological Parameters Relevant to Dissolution Testing

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