Shear distribution and variability in the USP Apparatus 2 under turbulent conditions

Kukura, J; Baxter, Jennifer L.; Muzzio, Fernando J.

doi:10.1016/j.ijpharm.2004.03.033

Cited by 97 publications

(93 citation statements)

References 15 publications

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“…In order to maintain the continuity of the pH monitoring and adjustment processes, both the pH electrode and the diffuser have to be continuously immersed in the dissolution medium during the test. Apparently, the placement of the pH electrode and the gas diffuser in the upper part of the dissolution vessel (∼3 cm below media surface) do not influence the hydrodynamic conditions at the bottom part of the vessel, where the dosage form is supposed to stay during the dissolution experiment in the paddle apparatus (20,21). However, the changes in the hydrodynamics caused by the gas diffuser as well as the electrode were not studied in the present work and require further investigations.…”

Section: Discussionmentioning

confidence: 85%

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: 85%

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

et al. 2013

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“…Drug release of a poorly soluble drug like EFV, as used in the study, is usually driven more by the medium than by the formulation ingredients. Discriminatory dissolution profiles are highly desirable for distinguishing between products showing differences in pharmaceutical attributes (formulation or manufacturing process differences) as is the case in the present study, wherein the difference in formulation was only with respect to the disintegrant used (10)(11)(12)(13). Figure 1 shows the dissolution profile of 600-mg EFV tablet in water containing different concentrations of SLS containing CP as disintegrant.…”

Section: In Vitro Dissolution Studiesmentioning

confidence: 88%

Impact of superdisintegrants on efavirenz release from tablet formulations

Yelchuri

Balasubramaniam

K³

et al. 2010

Acta Pharmaceutica

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EFV is a non-nucleoside reverse transcriptase inhibitor and is used as part of the highly active antiretroviral therapy for the treatment of human immunodeficiency virus type 1 (HIV) infection. It is also used in combination with other antiretroviral agents as part of an expanded post-exposure prophylaxis regimen to prevent HIV transmission for those exposed to materials associated with a high risk of HIV transmission.EFV has poor aqueous solubility and is a BCS class II drug (1). EFV tablets of 600 mg are available, while lower doses (50, 100 and 200 mg) are generally available as capsules and are prepared by a wet granulation process (2, 3). 185Acta Pharm. 60 (2010) [185][186][187][188][189][190][191][192][193][194][195] Original research paper DOI: 10.2478/v10007-010-0019-6 Impact of superdisintegrants on efavirenz release from tablet formulations Efavirenz (EFV) tablets of different doses were prepared by a wet granulation process using different superdisintegrants such as crosscarmellose sodium (CCS), sodium starch glycollate (SSG) and crosspovidone (CP) to evaluate the role of different disintegrants on the in vitro release of EFV. Further, the mode of addition of disintegrants on EFV dissolution from tablets containing 600 mg of the drug was evaluated by incorporating the disintegrants extragranularly (EG), intragranularly (IG) or distributing them equally (IG and EG). In vitro dissolution of the prepared tablets was conducted using the recommended medium and a dissolution medium developed in-house, which had the ability to discriminate between the formulations.The t 50 and t 80 values were indicative of the fact that the drug release was faster from tablet formulations containing CP. CP was able to release the drug faster than the other two disintegrants in both dissolution media and the drug release was unaffected by the mode of CP addition.Keywords: efavirenz, superdisintegrants, granulation * Correspondence; e-mail: rajeshyelchuri@rediffmail.com Brought to you by | MIT Libraries Authenticated Download Date | 5/12/18 2:48 PM Superdisintegrants generally improve disintegration efficiency compared to traditional disintegrants. They are generally used at low levels in solid dosage forms, typically 1-10 % of mass relative to the total mass of the dosage unit (4). Examples of superdisintegrants are crosscarmellose sodium (CCS), sodium starch glycollate (SSG) and crosspovidone (CP), which are cross-linked cellulose, a cross-linked starch and a cross--linked polymer (polyvinyl pyrrolidone), respectively. Wet granulation is one of the frequently used techniques to prepare blends to be compressed into tablets. The disintegrant can be incorporated in the blend before granulation, referred to as intragranular addition (IG), or after granulation, referred to as extragranular addition (EG), or it can be distributed both intra and extragranularly. EXPERIMENTAL MaterialsEfavirenz (Aurbindo Pharma Ltd., India) was purchased from the source indicated. Crosscarmellose sodium (Ac-di-sol ® , FMC biopolymer) and SS...

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“…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: 95%

“…As the surface of the tablet dissolved, the pink color of the phenolphthalein indicator in the clear sodium hydroxide dissolution medium indicated the flow direction in the medium surrounding the tablet (20). Laser-induced fluorescence, introduced as a quantitative technique in the previous section, can also be used to visualize and characterize mixing in a flow field (21). Flow visualization can be achieved by the photography of the flow field capturing the fluorescence emission (22).…”

Section: Magnetic Resonance Imagingmentioning

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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Shear distribution and variability in the USP Apparatus 2 under turbulent conditions

Cited by 97 publications

References 15 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

Impact of superdisintegrants on efavirenz release from tablet formulations

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

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