Flow-through Cell Method Research Articles

Bicarbonate buffer dissolution test with gentle mechanistic stress for bioequivalence prediction of enteric-coated pellet formulations

This study aimed to develop a dissolution test that can predict the bioequivalence (BE) of enteric-coated pellet formulations. The original duloxetine hydrochloride capsule (reference formulation (RF); Cymbalta® 30 mg capsule) and four generic test formulations (two capsules (CP) and two orally disintegrating tablets (OD)) were used as model formulations. Clinical BE studies were conducted on 24–47 healthy male subjects under fasting conditions. Dissolution tests were performed using a compendial paddle method (PD) (paddle speed: 50 rpm) and a flow-through cell method (FTC) (flow rate: 4 mL/min). For a further test, cotton balls were added to the vessel to apply gentle mechanistic stress to the formulations, and paddle speed was reduced to 10 rpm (paddle with cotton ball method (PDCB)).All the dissolution tests were conducted with 0.01 M HCl (pH 2.0) for 0.5 h followed by 10 mM bicarbonate buffer solutions (pH 6.5) for 4 h. One each of the two CP and two OD showed BE with RF. PDCB was able to discriminate between BE and non-BE formulations, while this was not possible with PD and FTC. In PDCB, the cotton balls intermittently moved the pellets near the vessel bottom. PDCB is useful for predicting BE during formulation development.

Advantage analysis of flow-through cell method in quality evaluation of Chinese patent medicine: a case study of Danshen Tablets

To explore the quality consistency evaluation method for multi-component traditional Chinese medicine and establish a dissolution evaluation method suitable for the characteristics of multi-component Chinese patent medicine, this study discussed the characteristics and advantages of the flow-through cell method in the dissolution evaluation of Chinese patent medicine by comparing the impact of the small cup method and the flow-through cell method on the dissolution behavior of water-soluble and lipid-soluble major active components of Danshen Tablets. Dissolution tests were performed using the small cup method as described in the 2020 edition of the Chinese Pharmacopoeia and the newly introduced flow-through cell method(closed-loop method) with water solution containing 0.5% SDS as dissolution medium. Cumulative dissolution curves of the water-soluble component salvianolic acid B and the lipid-soluble component tanshinone Ⅱ_A in Danshen Tablets were plotted, and fitting and similarity analysis of the dissolution models was conducted to identify the characteristics and advantages of the flow-through cell method. For the small cup method, 150 mL of water containing 0.5% SDS was used as the dissolution medium, with a rotation speed of 75 r·min~(-1) and a temperature of(37±0.5) ℃, and 3 mL of samples were taken at 15, 30 min, 1, 2, and 4 h, with fresh dissolution medium added at the same temperature and volume. For the flow-through cell method, a closed-loop system was used. Danshen Tablets were placed in the flow-through cell with approximately 6.7 g of glass beads, and 150 mL of water containing 0.5% SDS was used as the dissolution medium. The flow rate was set at 20 mL·min~(-1), and the temperature and sampling were the same as the small cup method. The results showed that compared with the small cup method, the flow-through cell method had stronger discriminative power and higher sensitivity in distinguishing the dissolution behavior of the two components, and could better reflect the differences in formulation quality, especially for water-insoluble lipid-soluble components. Given that there were no essential differences in the in vitro release kinetics between the two methods, the flow-through cell method could not only replace the traditional small cup method but also better guide the formulation development and identify quality issues of formulations.

Development of bicarbonate buffer flow-through cell dissolution test and its application in prediction of in vivo performance of colon targeting tablets

The purpose of this study was to develop a bicarbonate buffer flow-through cell (FTC) dissolution test. Mesalazine colon targeting tablets of a generic development product (test formulation, TF; Mesalazine 400 mg tablet) and the original product (reference formulation, RF; Asacol® 400 mg tablet) were used as model formulations. A clinical bioequivalence (BE) study was conducted on 48 healthy male subjects under fasting conditions. The oral absorption time profiles were calculated by point-area deconvolution. The compendial paddle and FTC apparatus were used for dissolution tests. Bicarbonate or phosphate-citrate buffer solutions (McIlvaine buffer) were used as the dissolution media. A floating lid was used to maintain the pH value of the bicarbonate buffer solution in the vessel (paddle) or the reservoir (FTC). In the development of bicarbonate FTC method, the pH changes of bicarbonate buffer solution (pH 5.5–7.5; 5–50 mM bicarbonate) were evaluated. For the evaluation of colon targeting tablets, the dissolution profiles of TF and RF were measured at a pH of 7.5. The TF and RF formulations were exposed to 0.01 HCl (pH 2.0) for 2 h before pH 7.5. In the clinical BE study, drug dissolution started 4–8 h after oral administration and continued slowly more than 10 h. Both the area under the curve (AUC) and maximum plasma concentration (Cmax) of TF were approximately twice as high as those of RF. In the development of the bicarbonate FTC method, the pH change of the bicarbonate buffer solution was suppressed by the floating lid within ∆pH < 0.1 over 10 h. In the dissolution test of McIlvaine buffer solutions, TF and RF showed faster disintegration and higher dissolution than those observed in the clinical BE study. When using the paddle apparatus the dissolution profiles of TF and RF in both buffer solutions were not consistent with those of the clinical result. In bicarbonate FTC, the disintegration time, dissolution rate, and dissolution inequivalence between TF and RF were consistent with the results of the clinical BE study. In conclusion, the bicarbonate FTC method was constructed for the first time in this study. This method is simple and practically useful for predicting in vivo performance of colon targeting tablets during drug development.

Recent Progress in Drug Release Testing Methods of Biopolymeric Particulate System.

Biopolymeric microparticles have been widely used for long-term release formulations of short half-life chemicals or synthetic peptides. Characterization of the drug release from microparticles is important to ensure product quality and desired pharmacological effect. However, there is no official method for long-term release parenteral dosage forms. Much work has been done to develop methods for in vitro drug release testing, generally grouped into three major categories: sample and separate, dialysis membrane, and continuous flow (flow-through cell) methods. In vitro drug release testing also plays an important role in providing insight into the in vivo performance of a product. In vitro release test with in vivo relevance can reduce the cost of conducting in vivo studies and accelerate drug product development. Therefore, investigation of the in vitro–in vivo correlation (IVIVC) is increasingly becoming an essential part of particulate formulation development. This review summarizes the principles of the in vitro release testing methods of biopolymeric particulate system with the recent research articles and discusses their characteristics including IVIVC, accelerated release testing methods, and stability of encapsulated drugs.

COMPARATIVE DISSOLUTION STUDIES OF WARFARIN SODIUM TABLETS: INFLUENCE OF AGITATION RATE, DISSOLUTION MEDIUM, AND USP APPARATUS

Objective: The aim of this study was to carry out comparative dissolution studies with warfarin sodium reference tablets under the hydrodynamic environments generated by the USP basket and paddle apparatus and flow-through cell using different agitation rates and dissolution media.&#x0D; Methods: Dissolution profiles were obtained with the USP basket and paddle apparatus at 50, 75, and 100 rpm and 900 ml of water as dissolution medium. After this, dissolution profiles of warfarin sodium were obtained with the USP paddle apparatus and flow-through cell method using 0.1 N hydrochloric acid, acetate buffer pH 4.5, phosphate buffer pH 6.8, and water. Spectrophotometric determination at 308 nm was carried out during 30 min. Dissolution profiles were compared with model-independent and model-dependent approaches.&#x0D; Results: Significant differences were found with mean dissolution time and dissolution efficiency at 50 and 75 rpm (*P&lt;0.05). Makoid-Banakar was the best-fit model used to describe the in vitro release performance of warfarin sodium with 50-100 rpm and the USP basket and paddle apparatuses. Significant differences in all calculated parameters were found (*P&lt;0.05) excepting percent dissolved at 30 min with 0.1 N hydrochloric acid and phosphate buffer pH 6.8.&#x0D; Conclusion: More research is necessary to identify the in vitro release performance of poorly soluble drugs under available USP apparatuses considering factors as agitation rate and kind of dissolution media. The knowledge of the in vitro release performance of reference drug products is important for the design of better generic formulations

IN VITRO RELEASE PERFORMANCE OF METFORMIN HYDROCHLORIDE FORMULATIONS USING THE FLOW-THROUGH CELL METHOD

Objective: The objective of this work was to evaluate the in vitro release performance of metformin hydrochloride formulations (500-mg tablets) using the hydrodynamic environment of the flow-through cell method. Results were compared with those generated by the official dissolution test (USP basket apparatus).&#x0D; Methods: The reference drug product and three generic formulations were tested with phosphate buffer pH 6.8 as dissolution medium. Dissolution profiles were carried out with an automated flow-through cell apparatus using laminar flow at 16 ml/min. Drug was quantified at 233 nm during 45 min. Dissolution profiles were compared with the calculation of f2 similarity factor, mean dissolution time, dissolution efficiency, t50% and t63.2%. Dissolution data were adjusted to several mathematical models such as Makoid-Banakar, Peppas-Sahlin, Weibull and Logistic.&#x0D; Results: With the flow-through cell method and at 45 min less than 60% of metformin hydrochloride dissolved was found, while with the USP basket apparatus, less than 75% of the drug was found. Some generic formulations showed f2&gt;50 with both USP apparatuses, but statistical comparisons of parameters indicated significant differences between their dissolution profiles and reference. Due to variability obtained no dissolution profiles were compared by model-dependent approach.&#x0D; Conclusion: To demonstrate safe interchangeability between metformin hydrochloride generic formulations and reference bioequivalence studies should be performed. It is important post-marketing monitoring of the commercial formulations because health regulatory agencies of each country must ensure drug products with quality, safety, and efficacy at the lowest possible cost.

А Study of Haloperidol Release from Polycomplex Nanoparticles Based on Eudragit&lt;sup&gt;®&lt;/sup&gt; Copolymers

Introduction . The development of polymer carriers for micro- and nanoscale drug delivery systems is an emerging area of modern pharmaceutical technology. One of the urgent needs in this area is the development of effective methods to study the drug release from these systems. Aim . This work aimed to study the release of a model drug (MD) haloperidol from polycomplex nanoparticles prepared based on interpolyelectrolyte complexes (IPEC) using various methods. Materials and methods . IPECs were prepared in the form of nanoparticles based on pharmaceutical polymers (Eudragit ® EPO and Eudragit ® L100-55). Size distribution of these nanoparticles were determined using dynamic light scattering on Zetasizer Nano-ZS equipment (Malvern Instruments, UK). The release of haloperidol was studied in a medium simulating an artificial nasal fluid using a vertical Franz diffusion cell (PermeGear, USA) as well as a modified USP IV method in a flow-through cell apparatus (DFZ II, Erweka, Germany). Results and discussion . Statistically significant increase in the release of haloperidol from polycomplex nanoparticles in contrast with the control (haloperidol solution) is observed when using a vertical diffusion or Franz cell, after almost 2.5 hours. At the same time, it was not possible to study the release of drug using the flow-through cell method (USP IV), due, apparently, to the effect of crystallization of haloperidol on the surface of dialysis membranes in the Float-A-Lyzer ® G2 nanoadapters. The attempts to eliminate this effect and to improve the membrane permeability to haloperidol by adding surfactants (tween-80) and penetration enhancers (DMSO) were not successful. Conclusion . Both methods are promising for studying the release of drugs from nanosized carriers; however, in the case of using poorly-soluble drugs, including haloperidol, the diffusion method using a vertical Franz cell is effective.

In vitro release studies of furosemide reference tablets: influence of agitation rate, USP apparatus, and dissolution media.

Furosemide is a diuretic drug widely used in chronic renal failure. The drug has low solubility and permeability, which cause clinical problems. Studying the in vitro release performance elucidates the rate and extent of drug dissolved from dosage forms under different conditions. Furosemide reference tablets were tested using USP Apparatuses 1 and 2 as well as the flow-through cell method (USP Apparatus 4), a dissolution apparatus that simulates the human gastrointestinal tract better than the other methods. Dissolution profiles were created with USP Apparatuses 1 and 2 at 25, 50, and 75 rpm and 900 mL of 0.1 M hydrochloric acid, acetate buffer (pH 4.5), and phosphate buffer (pH 6.8). USP Apparatus 4 with a laminar flow of 16 mL/min and 22.6 mm cells was used. Drug dissolution was quantified at 274 nm for 60 min. Mean dissolution time, dissolution efficiency, time to 50% dissolution, and time to 80% dissolution data were used to compare dissolution profiles. Additionally, zero-order, first-order, Higuchi, Hixson-Crowell, Makoid-Banakar, and Weibull models were used to adjust furosemide dissolution data. Between USP Apparatus 1 and 2, significant differences were observed in almost all parameters at 50 and 75 rpm (p < 0.05). A similar dissolution profile (f2 > 50) with a pharmacopoeial dissolution method (USP Apparatus 2 at 50 rpm and 900 mL of phosphate buffer pH 5.8) and USP Apparatus 4 (laminar flow of 16 mL/min, 22.6 mm cells, and pH 6.8) was observed. The Weibull function was the best mathematical model to describe the in vitro release performance of furosemide in the three USP dissolution apparatuses. These results could be used to manufacture better furosemide dosage forms and decrease the negative clinical impact of current furosemide formulations.

In Vitro-In Vivo Correlation for Solid Dispersion of a Poorly Water-Soluble Drug Efonidipine Hydrochloride.

The aim of this present study was to investigate the ability of different dissolution methods to predict the in vivo performance of efonidipine hydrochloride (EFH). The solid dispersions of EFH were prepared by solvent evaporation method with HPMC-AS as matrix and urea as a pH adjusting agent. The paddle method, the open-loop, and the closed-loop flow-through cell methods were studied. In the study, Weibull's model was the best fit to explain release profiles. The pharmacokinetics behaviors of two kinds of solid dispersions with different release rate were investigated in comparison to the EFH after oral administration in rats. In vivo absorption was calculated by a numerical deconvolution method. In the study, the level A in vivo and in vitro correlation (IVIVC) was utilized. The correlation coefficient was calculated and interpreted by means of linear regression analysis (Origin.Pro.8.5 software). As a result, excellent IVIVC for solid dispersions and crude drug (r2 = 0.9352-0.9916) was obtained for the dissolution rate determined with flow-through cell open-loop system in phosphate buffer solution with 0.1% (w/v) polysorbate 80 at pH 6.5, the flow-rate of 4mL/min. In addition, the self-assembled flow cell system had good repeatability and accuracy. The dissolution rate of the solid dispersion could be slowed down by the flow-through method, and the difference caused by preparation was significantly distinguished. The study demonstrated that flow-through cell method of the open-loop, compared with paddle method, was suitable for predicting in vivo performance of EFH solid dispersions.

Design of Dissolution Apparatus for the Flow-through Cell Method Based on the Low Pulsation Peristaltic Pump

Design of Dissolution Apparatus for the Flow-through Cell Method Based on the Low Pulsation Peristaltic Pump

DISSOLUTION PERFORMANCE OF MELOXICAM FORMULATIONS UNDER HYDRODYNAMICS OF USP PADDLE APPARATUS AND FLOW-THROUGH CELL METHOD

Objective: To study the in vitro dissolution performance of four generic formulations of the poorly soluble drug meloxicam and the reference under hydrodynamic environments generated by flow-through cell method and USP paddle apparatus (pharmacopeial test).&#x0D; Methods: Dissolution method was validated according to ICH guidelines. Dissolution profiles were carried out with an automated flow-through cell apparatus (laminar flow at 16 ml/min with 22.6 mm cells) and USP paddle apparatus at 75 rpm. Phosphate buffer pH 7.5 at 37.0±0.5 °C was used as dissolution medium. Spectrophotometric determination of drug at 362 nm was carried out during 30 min. Dissolution profiles were compared with model-dependent and-independent methods.&#x0D; Results: Practically, all generic formulations showed significant differences with the percentage of drug dissolved at 30 min, mean dissolution time and dissolution efficiency, when USP paddle apparatus was used (*P&lt;0.05), while only two generic formulations were different to reference using flow-through cell method. After adjustment to different mathematical equations, Weibull function was the best model to describe meloxicam dissolution performance and significant differences were found with all drug products when USP paddle apparatus was used, while only one formulation was different with flow-through cell method.&#x0D; Conclusion: The study reveals the need to look for better dissolution schemes for meloxicam tablets since USP paddle apparatus may not reflect properly the in vitro dissolution performance of meloxicam generic formulations and reference.

INFLUENCE OF DOSE AND USP DISSOLUTION APPARATUS IN THE RELEASE PERFORMANCE OF REFERENCE TABLETS: PROPRANOLOL-HCl AND RANITIDINE-HCl CASES

Objective: Due to quality of generic formulations depends on available information of reference drug products the aim of this work was to perform an in vitro dissolution study of two doses of propranolol-HCl and ranitidine-HCl reference tablets using USP basket or paddle apparatus and flow-through cell method.&#x0D; Methods: Two doses of propranolol-HCl (10-mg and 80-mg) and ranitidine-HCl (150-mg and 300-mg) of Mexican reference products were used. Dissolution profiles of propranolol-HCl were obtained with USP basket apparatus at 100 rpm and 1000 ml of 1% hydrochloric acid. Profiles of ranitidine-HCl were determined with USP paddle apparatus at 50 rpm and 900 ml of distilled water. All formulations were also studied with the flow-through cell method using laminar flow at 16 ml/min. Dissolution profiles were compared by model-independent (f2 similarity factor, mean dissolution time and dissolution efficiency) and model-dependent methods (dissolution data adjusted to some mathematical equations). Time data, derived from these adjustments, as t50%, t63.25%, and t85% were used to compare dissolution profiles.&#x0D; Results: With all approaches used and being high solubility drugs significant differences were found between low and high doses and between USP dissolution apparatuses (*P&lt;0.05).&#x0D; Conclusion: In vitro dissolution performance of two doses of propranolol-HCl and ranitidine-HCl was not expected. Considering the same USP dissolution apparatus, the reference tablets did not allow the simultaneous release of the used doses. The results could be of interest for pharmaceutical laboratories or health authorities that classify some drug products as a reference to be used in dissolution and bioequivalence studies.

Novel Dissolution Approach for Tacrolimus-Loaded Microspheres Using a Dialysis Membrane for in Vitro-in Vivo Correlation.

The aim of this study was to establish a novel approach to in vitro dissolution evaluation using a combination of the paddle method and a dialysis membrane, both to predict the overall in vivo performance of tacrolimus microspheres and also to identify a suitable dissolution test method to describe the in vivo initial burst phenomenon. This new dissolution method for evaluating the release of tacrolimus from microspheres consisted of rotating a customized paddle inside a dialysis membrane using a conventional paddle apparatus. Findings were compared with a method in which the paddle was rotated outside the dialysis membrane, the conventional paddle method, and the flow-through cell method. We concluded that the paddle method with a dialysis membrane and internal agitation, which was designed to mimic in vivo conditions, predicted the overall pharmacokinetic (PK) profile of tacrolimus microspheres whereas the conventional paddle method described the initial burst. These findings suggest that it may not be possible to predict both the PK profile and initial burst using a single analysis method. We therefore recommend that evaluation of the initial burst be performed separately. In conclusion, we propose that combination of the paddle method with a dialysis membrane and internal agitation to evaluate the overall PK profile, together with the paddle method to describe the in vivo initial burst, represents a novel approach to in vitro dissolution evaluation for microsphere formulations.

Influence of Dissolution Vessel Geometry and Dissolution Medium on In Vitro Dissolution Behaviour of Triamterene-Coated Model Stents in Different Test Setups.

The aim of this study was to investigate if the geometry of the dissolution vessel, the dissolution medium volume and composition might contribute to the variation in drug release from drug-eluting stents (DES) in different test setups, which has been observed in previous in vitro studies. Therefore, DES containing triamterene as model substance were produced via fluidised-bed technology. Dissolution testing was carried out using different incubation setups, the reciprocating holder (USP Apparatus 7) and two flow-through methods, a method similar to the USP Apparatus 4 (FTC) and the vessel-simulating flow-through cell (vFTC) equipped with a hydrogel as a second compartment simulating the blood vessel wall. The results indicate that dissolution vessel geometry and medium volume had no influence on the release behaviour and only the flow-through cell methods yielded a lower dissolution rate than the incubation setups (80.6 ± 2.0% released in the FTC after 14days compared to > 90% for all incubation setups). The composition of the hydrogel used in the vFTC also affected the dissolution rate (53.9 ± 4.5% within 14days with a hydrogel based on phosphate-buffered saline compared to 78.2 ± 1.2% obtained with a hydrogel based on water) possibly due to different solubility of triamterene in the release media as well as interactions between the coating polymer and the release medium. Hence, the introduction of a hydrogel as a second compartment might lead to a more biorelevant test setup.

Phase separation of supersaturated solution created from amorphous solid dispersions: Relevance to oral absorption

Dissolution of amorphous solid dispersions (ASDs) is a complicated process, which may involve phase separation from the supersaturated state and formation of a colloidal phase. However, relevance of the phase separation behavior to oral absorption from ASDs is still not well understood. We investigated phase separation of a supersaturated fenofibrate (FEN) solution in the presence of polymers, in vitro dissolution of FEN ASDs, and their in vivo absorption. The supersaturation behavior was assessed based on turbidity measurement in an artificial supersaturation system, where FEN ethanol solutions were added to aqueous polymer solutions. The phase separation concentration of FEN was ca. 1 μg/mL regardless of the presence/absence of the polymer, which was approximately 10-fold the equilibrium solubility. In the presence of 0.1% Tween 80 in the media, the phase separation concentration depended on the polymer species, presumably due to differences in their inhibitory effect of crystallization. The degrees of supersaturation achieved by the ASDs were similar to those found in the artificial system, suggesting that the artificial system works for comprehending the effect of polymer species on supersaturation ability for designing ASDs. A robust in vitro-in vivo correlation was achieved using the paddle and the flow-through cell methods by employing non-sink and pH-shift conditions. However, the phase separation concentration may rather be a good and simple indicator to estimate the absorption-enhancing ability of the polymeric excipients for ASDs, if the absorption is limited by solubility.

DISSOLUTION BEHAVIOR OF CARBAMAZEPINE SUSPENSIONS USING THE USP DISSOLUTION APPARATUS 2 AND THE FLOW-THROUGH CELL METHOD WITH SIMULATED GI FLUIDS

Objective: To characterize the dissolution behaviour of carbamazepine generic suspensions using the USP Dissolution Apparatus 2 and the flow-through cell method with simulated gastrointestinal fluids as dissolution media.Methods: Tegretol® suspension and two generic formulations were tested. Dissolution studies were performed using the USP Apparatus 2 (75 rpm and 900 ml of dissolution medium) and the flow-through cell method (laminar flow at 16 ml/min). Simulated gastric fluid (SGF) (with and without pepsin) and simulated intestinal fluid (SIF) (without pancreatin) at 37.0±0.5 °C, was used as dissolution media. The quantity of dissolved carbamazepine was determined at 5 min intervals until reaching 60 min, at 285 nm. Percentage dissolved at 60 min, mean dissolution time, dissolution efficiency values (model-independent parameters), as well as t50% and t63.2% were calculated (model-dependent parameters). Values for all parameters were compared between the reference and generic formulations using one-way analysis of variance (ANOVA) following a Dunnett’s multiple comparison test. Dissolution data were also fitted to different fit models.Results: Since the first sampling time, the reference product had reached 100% of drug dissolved, which was determined using USP Apparatus 2. Nevertheless, significant differences in the three model-independent parameters of generic products were found (*P&lt;0.05). Dissolution data obtained with the paddle apparatus were fitted to different kinetic equations; however, using the flow-through cell method and SIF without pancreatin, the three drug products were fitted to the same kinetic model (Gompertz). With ANOVA-based comparisons and the flow-through cell method, significant differences were found in dissolution data of generic product A versus reference at all sampling times (*P&lt;0.05). The flow-through cell method and SGF with pepsin were the best options to discriminate among dissolution profiles.Conclusion: The flow-through cell method seems to be an adequate dissolution apparatus to characterize in vitrodissolution performance of Class II drugs manufactured as suspensions. For carbamazepine suspensions, SGF and laminar flow at 16 ml/min were the most appropriate conditions to discriminate among generic formulations. Given the physicochemical characteristics of carbamazepine and the environment in which the drug products were tested, these differences could be of clinical relevance.

USP Apparatus 4: a Valuable In Vitro Tool to Enable Formulation Development of Long-Acting Parenteral (LAP) Nanosuspension Formulations of Poorly Water-Soluble Compounds.

Long-acting or extended release parenteral dosage forms have attracted extensive attention due to their ability to maintain therapeutic drug concentrations over long periods of time and reduce administration frequency, thus improving patient compliance. It is essential to have an in vitro release (IVR) testing method that can be used to assure product quality during routine production as well as predict and understand the in vivo performance of a formulation. The purpose of this work was to develop a discriminatory in vitro release method to guide formulation and process development of long-acting parenteral (LAP) nanosuspension formulations composed of poorly water-soluble drugs (BCS class II). Injectable nanosuspension formulations were developed to serve as test articles for method development. Several different IVR methods were evaluated for their application to the formulation screening and process development including (1) USP apparatus 2, (2) dialysis and reverse dialysis sac, and (3) continuous flow-through cell (USP apparatus 4). Preliminary data shows the promising results to support the utilization of USP 4 over more widely accepted USP 2 and dialysis methods. A combination of more representative in vivo hydrodynamics and ease of maintaining sink conditions yields the USP 4 flow-through cell method a more suitable in vitro release method for nanosuspension-based LAP formulations of poorly water-soluble compounds, such as compounds A and B.

COMPARISON OF THE USP APPARATUS 2 AND 4 FOR TESTING THE IN VITRO RELEASE PERFORMANCE OF IBUPROFEN GENERIC SUSPENSIONS

Objective: The aim of this study was the comparison of the in vitro release performance of ibuprofen generic suspensions and reference, based on the hydrodynamic environment generated by the flow-through cell method (USP Apparatus 4). Results were compared with those obtained by the use of the USP Apparatus 2.Methods: The Advil® suspension (2 g/100 ml) and two generic formulations with the same dose were tested. Dissolution studies were carried out using a USP Apparatus 4 Sotax CE6 with 22.6 mm cells, laminar flow at 16 ml/min, and pH 7.2 phosphate buffer at 37.0±0.5 °C as dissolution medium. Ibuprofen was quantified spectrophotometrically at 222 nm. The in vitro release of the three drug products were studied using the USP Apparatus 2. The dissolution profiles of generic products were compared with the reference by model-independent, model-dependent, and analysis of variance (ANOVA)-based comparisons.Results: The dissolution profile of the generic product A was similar to the dissolution profile of reference, only with the use of the USP Apparatus 4. The f2 similarity factor was&gt;50 and no significant differences were found with dissolution efficiency data (*P&gt;0.05). Similar results were found with the comparison of t50% and t63.2% values. Similar dissolution profiles between generic product A and reference were also found with ANOVA-based comparisons.Conclusion: The flow-through cell method was adequate for study the in vitro release of ibuprofen suspensions. It is necessary to evaluate the in vivoperformance of the drug products used in order to estimate the predictability of the proposed methodology.

Characterization of orally disintegrating films: A feasibility study using an electronic taste sensor and a flow-through cell

In the early development stage of orally disintegrating films (ODFs), suitable evaluation methods must be used. The aim of this study was to demonstrate the feasibility of using an electronic taste sensor and a flow-through cell for ODFs. A pullulan film loaded with donepezil hydrochloride (DH) was designed, as a model ODF. The film was prepared using the solution/solvent casting method. First, the dissolution profiles were compared by using a paddle method (PD) and a flow-through cell method (FT) under three flow rates. Dissolution tests using both methods were carried out successfully. Secondly, the bitterness of ODFs was determined by a new system combining a flow-through cell apparatus and an electronic taste sensor apparatus. The results indicated that the FT method can collect eluate for the bitterness test. They also suggested that these methods are useful for evaluating ODFs. The sensor output was strongly correlated with the dissolution behavior at the initial stage of administration. This new system with a flow-through cell and an electronic taste sensor could be used to evaluate the palatability of ODFs and to improve film formulation.

Comparative release studies on suppositories using the basket, paddle, dialysis tubing and flow-through cell methods I. Acetaminophen in a lipophilic base suppository

The release characteristics of lipophilic suppositories containing acetaminophen (AAP) were examined using four types of dissolution methods: the basket, paddle, dialysis tubing (DT) and flow-through cell (FTC) methods. The suitability of each apparatus for quality control in AAP compounded suppositories was evaluated using statistical procedures. More than 80% of the drug was released over 60 min in all the release methods studied, with the exception of the basket method. Reproducible and faster release was achieved using the paddle method at 100 and 200 rpm, whereas poor release occurred with the basket method. The mean dissolution time (MDT), maximum dissolved quantity of AAP at the end of the sampling time (Q) and dissolution efficiency (DE) were calculated by model-independent methods. The FTC method with a single chamber used in this study was also appreciable for AAP suppositories (Q of 100%, MDT of 71–91 min and DE of 75–80%). The DT apparatus is considered similar to the FTC apparatus from a quality control perspective for judging the release properties of lipophilic base suppositories containing AAP. However, even the single chamber FTC used in this study has potential as an in vitro drug release test for suppositories. The comparative dissolution method is expected to become one of the valuable tools for selecting an adequate dissolution test.