Hydrodynamic Investigation of USP Dissolution Test Apparatus II

Bai, Ge; Armenante, Piero M.; Plank, R. V.; Gentzler, Michael; Ford, Kenneth; Harmon, Paul A.

doi:10.1002/jps.20818

Cited by 95 publications

(133 citation statements)

References 21 publications

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“…In the tests performed at pH 7.4, somewhat higher fluctuations with values of ΔpH ranging from −0.03 up to −0.04 pH units were noticed immediately after purging. The observed "overregulation" is related to the slower reaction rate of CO 2 (gas) dissolution and dissociation as well as to test parameters, such as the amount of titer gas remaining in the tubing that connects the proportional valve with the diffuser, the electrode response and the mixing conditions in the USP Apparatus II (16)(17)(18)(19). However, both the dynamics and the precision of the pH adjustment can be regulated flexibly by appropriately setting the pressure of the titer gas introduced into the device as well as by the adjusting the device settings such as trigger pH difference, regulation range, and hysteresis.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2013

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Abstract. 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 (CO 2 ) from the solution results in an uncontrolled increase of the pH. In order to maintain the pH on the desired level, either a CO 2 loss must be completely avoided or the escaped CO 2 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.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2013

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“…The recirculation loop described in the lower part of the vessel may not penetrate the very low velocity region at the center of the vessel base (26), which explains this frequently observed coning phenomenon. It is possible to predict the minimum rotation speed at which the cone will disappear based on an application of the Zwietering equation (32,33).…”

Section: Coningmentioning

confidence: 93%

“…Recirculation loops have been identified in both the upper and lower sections of the vessel, with a weak positive axial flow under the impeller in the center of lower part of the vessel. Overall fluid velocity values and shear rates in the vessel base are very low, especially at the center of the vessel base compared to other regions of the vessel (13,21,(24)(25)(26)(27).…”

Section: General Flow Featuresmentioning

confidence: 94%

“…Under the standard operating conditions mandated by the dissolution test procedure, with no tablets present in the vessel, the shear strain environment in USP Apparatus 2 is highly heterogeneous with strain rate and fluid velocities varying significantly along the vessel base (21,(24)(25)(26)(27)29). These heterogeneous hydrodynamic conditions are present in the vessel base region where a dosage form is likely to be located.…”

Section: Hydrodynamics In the Lower Hemispherical Section Of The Vesselmentioning

confidence: 99%

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Characterization and Simulation of Hydrodynamics in the Paddle, Basket and Flow-Through Dissolution Testing Apparatuses - A Review

Todaro¹,

Pearsons²,

Grove³

et al. 2017

Dissolution Technol.

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Fluid velocity local to the dissolving surface will affect the dissolution rate. It is difficult to anticipate what local fluid velocities are present within compendial dissolution apparatuses from set flow rates or stirring rates. A range of qualitative and quantitative velocimetric techniques are available to assess and characterize hydrodynamics. These methods are frequently used in combination with computational fluid dynamics simulations to characterize and simulate hydrodynamics. Dosage form location and motion varies between apparatuses, and the presence of the dosage form itself can impact local hydrodynamics. Each apparatus described has identified hydrodynamic features which may also vary with agitation rate. This review describes the methods used to simulate and characterize hydrodynamics and summarizes some of the main findings from studies investigating hydrodynamics in the paddle, basket, and flowthrough dissolution apparatuses.

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“…In addition, and to make the system more sensitive to the effect of small geometric differences, tests were also conducted with tablets fixed at several positions in the vessel. As shown in previous studies by this group (25)(26)(27), tablets placed at different locations on the vessel bottom can have different dissolution rates since they experience different flows around them and different shear stresses, especially if the system is nonsymmetrical. Therefore, in this work, dissolution tests were conducted not only with the standard tablet drop technique specified in the USP (28), but also with tablets fixed in place at nine positions on the vessel bottom (i.e., the central position, four positions on the 10° off-center circle, and four other positions on the 20° off-center circle).…”

mentioning

confidence: 84%

Effect of a Fiber-Optic Probe on the Dissolution of Salicylic Acid Tablets in USP Apparatus 2

Bing¹,

Bredael²,

Armenante³

2013

Dissolution Technol.

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Fiber-optic probes permanently inserted in the dissolution medium in dissolution vessels can automate the sampling process but can also potentially affect the hydrodynamics in the vessel, possibly resulting in increased drug dissolution rates. In this work, dissolution experiments with non-disintegrating salicylic acid calibrator tablets were conducted in dissolution testing Apparatus 2 in both the presence and absence of a commercially available fiber-optic probe (Opt-Diss). Tests were conducted using tablets dropped in the medium according to USP guidelines, as well as with tablets fixed at nine positions on the vessel bottom (i.e., either centered in the vessel or placed at different off-center locations with respect to the vessel vertical centerline). The results were compared using statistical tools. In many cases, the presence of the probe resulted in slightly faster dissolution rates. The difference between the results obtained in experimental systems with the probe and those obtained with the control system without the probe depended on tablet position. Larger differences were observed when the tablets were on inner circle positions (10° off-center circle), especially when the tablets were located immediately downstream of the probe. A paired t-test as well as the difference factor (f 1 ) and similarity factor (f 2 ) were used to statistically analyze the results. In most cases, the results obtained with the inserted probe were statistically different, according to the paired t-test, from those obtained without it. It can be concluded that fiber-optic sampling probes can often result in small but measurable enhancements in the dissolution rates, which can produce appreciable variations in test results.

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Hydrodynamic Investigation of USP Dissolution Test Apparatus II

Cited by 95 publications

References 21 publications

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

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

Characterization and Simulation of Hydrodynamics in the Paddle, Basket and Flow-Through Dissolution Testing Apparatuses - A Review

Effect of a Fiber-Optic Probe on the Dissolution of Salicylic Acid Tablets in USP Apparatus 2

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