Dissolution Samples Research Articles

A VALIDATED STABILITY INDICATING ION EXCHANGE CHROMATOGRAPHIC METHOD FOR THE QUANTIFICATION OF ALENDRONATE, PHOSPHITE AND PHOSPHATE IN ALENDRONATE SODIUM TABLETS AND ANALYSIS OF IN-VITRO DISSOLUTION SAMPLES

A stability-indicating LC method was developed on ion exchange chromatography equipped with refractive index detector for the quantification of phosphite, phosphate content and assay of alendronic acid in pharmaceutical dosage forms. The isocratic separation was achieved by using Allsep anion (150mm x 4.6mm) 7 µm column with mobile phase containing a 5.3 mM formic acid, pH adjusted to 3.5 with sodium hydroxide solution at a flow rate of 1.2 mL/min. Alendronate sodium was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Alendronate sodium was found to degrade significantly in oxidative stress conditions only. The developed method was extensively validated as per ICH guidelines with respect to specificity, linearity, limit of detection and quantification, accuracy, precision and robustness. The developed LC method was successfully applied for analysis of in-vitro dissolution samples of marketed alendronate sodium tablets.

Development and Validation of a Dissolution Test Method for Artemether and Lumefantrine in Tablets

Purpose: To develop and validate a dissolution test method for dissolution release of artemether and lumefantrine from tablets. Methods: A single dissolution method for evaluating the in vitro release of artemether and lumefantrine from tablets was developed and validated. The method comprised of a dissolution medium of 1000 ml of 2 %w/v of Myrj 52 in 0.005M HCl per vessel with the paddle rotating at 100 rpm for 120 min. The dissolution samples were analysed using a Waters HPLC system with Waters symmetry column (C-18 column of 250mm x 4.6mm i.d., 5 μ particle size). The mobile phase was a mixture of 20 volumes of 0.5 %v/v of triethylamine in water (adjusted to a pH of 3.0 with orthophosphoric acid) and 80 volumes of acetonitrile. The detection wavelength was set at 216 nm and 100 μl of each sample was injected. The HPLC method used for the determination of drug release was validated for the parameters of accuracy, precision, linearity, specificity, filter validation, solution stability and robustness. Results: The dissolution test provided sink conditions for artemether and lumefantrine and was able to discriminate between tablet formulations of different hardness and different composition. Application of Mann-Whitney U test for significant difference between samples at various time points during the dissolution test yielded z values > 1.96 (1.96 = critical z value at p = 0.05) for the various formulations tested, indicating the discriminatory power of the dissolution test. Conclusion: This validated dissolution test may be used as a single dissolution test for artemether and luminfantrine in tablet formulations. Keywords: Artemether, Lumefantrine, Tablet formulations, Single dissolution test, HPLC

Development and application of a validated gradient elution HPLC method for simultaneous determination of 5-fluorouracil and paclitaxel in dissolution samples of 5-fluorouracil/paclitaxel-co-eluting stents

The combined use of 5-fluorouracil and paclitaxel is common in clinical trials. However, there are few methods for simultaneous determination of 5-fluorouracil and paclitaxel; most reported approaches can only quantitate either 5-fluorouracil or paclitaxel. This paper proposes a new gradient elution HPLC method for simultaneous determination of 5-fluorouracil and paclitaxel using a photodiode array detector, C 18 column (250 mm × 4.6 mm, 5 μm) with methanol and 0.5% H 3PO 4 aqueous solution as the mobile phase components. The injection volume was 50 μl and the column temperature was maintained at 30 °C. The method was validated according to USP Category I requirements. The validation characteristics included system suitability, linearity, analytical range, LOD, LOQ, accuracy, precision, specificity, stability, ruggedness and robustness. The calibration curves exhibited linear concentration ranges of 0.2–40 μg/ml for 5-fluorouracil and 1.5–150 μg/ml for paclitaxel with correlation coefficients larger than 0.99990. The lower limits of quantitation were 2 ng/ml for 5-fluorouracil and 0.75 μg/ml for paclitaxel, respectively. The intra and inter-day precision and accuracy were found to be well within acceptable limits (i.e., 5%). The results demonstrate that this method is reliable, reproducible and suitable for simultaneous quantitation of the two drugs in the release media of 5-fluorouracil/paclitaxel-co-eluting stents.

Development and validation of discriminating method of dissolution for fosamprenavir tablets based on in vivo data

The aim of this work is to develop and validate a dissolution test for fosamprenavir tablets (Telzir ®) based on in vivo data. The appropriate conditions were determined after testing sink conditions in dissolution medium, rotation speed and stability of the drug. In vivo release profiles were obtained from the literature. The fraction (and percentage) of dose absorbed (FA) was calculated by deconvolution, using the Wagner–Nelson method. For this formulation, the best dissolution conditions were achieved using a USP apparatus 1 900 ml of medium containing HCl 0.01 M at a rotation speed of 75 rpm. Under these conditions a significant linear relationship between fraction of drug absorbed versus dissolved was obtained ( R 2 = 0.984) and a level-A IVIVC was established. The in vitro dissolution samples were analyzed using a HPLC method and the validation was performed according to USP protocol. The method showed accuracy, precision, linearity and specificity within the acceptable range. The discriminatory power of the dissolution method was challenged. The kinetics of dissolution was determined using model-dependent methods. The dissolution profiles were best described by the Hixson–Crowell model. The dissolution test was validated and could be applied to evaluate the dissolution profile of fosamprenavir tablets.

Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine ( l-T 4) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250 mm × 3.9 mm) using a 0.01 M phosphate buffer (pH 3.0)–methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 μL and the column temperature was maintained at 28 °C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship ( r 2 > 0.99) over the analytical range of 0.08–0.8 μg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for l-T 4 over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets.

Dissolution of tanshinone ⅡA from Xianling Gubao capsule

To establish a method to determine the dissolution of Tanshinone IIA in xianling gubao capsules, and compare the dissolution of Xianling Gubao capsules prepared by different processes. The small cup method was used at a rotary speed of 100 r x min(-1), the dissolubility was inspected in the following 6 mediums: (1) water; (2) 0.1 mol x L(-1) hydrochloric acid solution; (3) pH 6.8 phosphate buffer; (4) pH 6.8 phosphate buffer solution + 0.5% cholic acid; (5) pH 6.8 phosphate buffer solution + 1.0% cholic acid; (6) pH 7.6 phosphate buffer solution + 4. 0% cholic acid. A HPLC method was used to determine the dissolution samples of tanshione IIA in different dissolution mediums. The accumulative dissolution percentages were calculated, and the resemblance of release curves were compared by similarity factors (f2). The accumulative dissolution percentage was the highest while pH 7.6 phosphate buffer solution + 4.0% cholic acid was used as medium. The similarity factor values (f2) of tanshinone IIA dissolution curves of different preparation processes of Xianling Gubao capsules were all less than 50. There is significant difference in tanshinone IIA dissolution between Xianling Gubao capsules of different preparation processes. The accumulative dissolution percentages of the tanshinone IIA in new Xianling Gubao capsules is higher than that in the capsules prepared by other preparation processes.

Development and validation of a dissolution test method for vitamin A in dietary supplement tablets

A dissolution test method and an analytical procedure by HPLC were developed and validated for evaluation of the dissolution behavior of dietary supplements tablets containing vitamin A in the forms of retinyl acetate or retinyl palmitate. Seven different commercially available products containing retinyl acetate or retinyl palmitate were selected for this study. A dissolution medium containing 1% (w/v) Octoxynol 9 (Triton X-100) and 1% (w/v) (+)-sodium α-ascorbate in 0.05 M phosphate buffer, pH 6.8, was found suitable to ensure sink conditions and chemical stability for both retinyl acetate and retinyl palmitate. Two rotation speeds, 50 and 75 rpm, were evaluated with USP Apparatus 2 and 900 ml dissolution medium. Dissolution profiles were generated over 120 min. Dissolution samples were analyzed with a reversed-phase HPLC method with UV detection at 325 nm. Each product was also assayed for vitamin A content according to USP 32–NF 27. The results from 45 min to the last time point of the dissolution tests performed at 75 rpm were consistent with the Assay results. The dissolution test described here could be proposed as a pharmacopeial standard to assess the performance of tablet formulations containing vitamin A as retinyl esters.

An HPLC method for the determination of digoxin in dissolution samples

An HPLC method for digoxin quantification in dissolution samples obtained as per the official British Pharmacopeia (BP) method is presented in this paper. The chromatography was performed at 20 ?C on a Symmetry C18; 3.5 ?m, 75 x 4.6 mm column with water - acetonitrile (72 : 28, v/v), as the mobile phase and UV detection at 220 nm. The method was found to be selective, linear, accurate and precise in the specified ranges. The LOD and LOQ were 0.015 ?g mL-1 and 0.050 ?g mL-1, respectively. Robustness testing was conducted to evaluate the impact of minor changes in the chromatographic parameters (i.e., acetonitrile fraction, flow rate of the mobile phase, column temperature and column length) on the characteristics of the digoxin peak. A. full factorial design (24) was used to investigate the influence of the four variables The presented HPLC method was applied in quality and stability testing of Digoxin tablets 0.25 mg.

Development and application of a validated HPLC method for the analysis of dissolution samples of mexiletine hydrochloride capsules

The aim of this work was to develop and validate a simple, efficient, sensitive and selective method for the analysis of dissolution samples of mexiletine hydrochloride capsules by HPLC without the necessity of any time-consuming extraction, dilution or evaporation steps prior to drug assay. Separation was performed isocratically on a 5 ?m LiChrospher 60, RP-Select B column (250 x 4 mm ID) using the mobile phase buffer-acetonitrile (60:42, v/v) at a flow rate of 1.2 mL min-1 and UV detection at 262 nm. The elution occurred in less than 10 minutes. The assay was linear in the concentration range 50-300 ?g mL-1 (r2 = 0.9998). The validation characteristics included accuracy, precision, linearity, specificity, limits of detection and quantification, stability, and robustness. Validation acceptance criteria were met in all cases (the percent recoveries ranged between 100.01 and 101.68 %, RSD &lt; 0.44 %). The method could be used for the determination of mexiletine hydrochloride and for monitoring its concentration in in vitro dissolution studies.

Development and validation of discriminatory dissolution procedure for poorly soluble glyburide

In the present study, parameters such as solubility, medium pH, surfactant type and dissolution behavior of formulations, influence of sink conditions, stability and discriminatory effect of dissolution testing were studied for the selection of a proper dissolution medium for glyburide (BCS Class II drug). Results of solubility data revealed that solubility increased with an increase in pH. Sink conditions were exhibited in the 0.05 M borate buffer pH 9.6, 0.05 M phosphate buffer pH 6.5 containing 0.1-2% (w/v) cetyl trimethyl ammonium bromide (CTAB) and 0.05 M phosphate buffer pH 7.4 containing 0.1- 2% CTAB (w/v), respectively. The 0.05 M phosphate buffer at pH 6.5 containing 0.1% CTAB (w/v) with an agitation speed of 50 rpm (USP II) showed a more discriminating drug release profile when compared with 0.05 M phosphate buffer at pH 7.4 containing 0.1% CTAB (w/v) with an agitation speed of 75 rpm. The spiked samples have shown better recovery at 50, 100 and 150% levels. There was no degradation, as observed in the mass spectrum of recovered dissolution samples when compared with the mass spectrum of standard drug solution, which promised that the method was specific and can be used for routine Quality Control analysis as well as for assessment of formulation variables in future dissolution studies of glyburide.

Automated zone‐sampling dilution by coupling sequential injection analysis to high‐throughput HPLC for the direct determination of gemfibrozil

A novel automated analytical scheme for the rapid determination of gemfibrozil in drug dissolution samples is reported. The procedure is based on direct coupling of a low pressure continuous flow technique such as sequential injection analysis (SI) to HPLC. SI performs automated dilution of the samples based on zone sampling and fills on-line the loop of the high pressure injection valve. Rapid separation of the analyte from the samples' matrix can be achieved in less than 1.0 min, by using a short RP monolithic column (25x4.6 mm id) at a flow rate of 2 mL/min. The SI and HPLC parts of the setup operate independently: during HPLC separation the next sample is treated by SI. This way a maximum throughput of 60 samples per hour is achieved allowing the complete analysis of a batch of six dissolution samples within 12-18 min based on the replicates. The proposed method was validated in terms of linearity, LOD and LOQ, precision, selectivity and accuracy. Its applicability was tested during quality control of four validation batches of a gemfibrozil-containing formulation. The results were in good agreement with the HPLC method proposed by the US Pharmacopeia.

Capillary electrophoresis determination of nitrate and nitrite in high-salt perchlorate solutions for the UC dissolution study

The capillary electrophoresis method with direct UV detection is proposed for the determination of nitrite and nitrate in high-salt perchlorate solutions issued from uranium carbide dissolution. The isotachophoretic sample stacking was used to compensate for the perchlorate matrix interference. Simple electrolyte composed of 120 mM formiate buffer, pH 3.8 enabled the nitrate and nitrite determination in the presence of up to 1000-fold excess of perchlorate with 2 µM and 4 µM detection limits for nitrate and nitrite, respectively. The proposed method was applied to the determination of nitrate and nitrite in high-salt non-irradiated uranium carbide dissolution samples.

PCA-CR analysis of dissolution profiles. A chemometric approach to probe the polymorphic form of the active pharmaceutical ingredient in a drug product

A simple chemometric approach to differentiate among the three crystalline polymorphs of the model drug Furosemide (FUR) in a pharmaceutical dosage form is presented. The proposed method is based on the principal component analysis with confidence regions (PCA-CR) comparison of the dissolution profiles of the test pharmaceutical formulation, and formulations containing the different polymorphs, employed as the corresponding references. For the elaboration of the references, FUR polymorphs I, II and III were prepared, characterized and compounded with the excipients found in the test commercial formulation. The dissolutions were carried out in a discriminating HCl–KCl dissolution medium (pH 2.2), and the corresponding profiles were constructed from the absorbances (274 nm) of the dissolution samples. PCA-CR was able to differentiate among the three crystalline polymorphs of FUR and to confirm the presence of polymorph I in the test sample, with 99% statistical confidence. The PCA-CR results were compared with those obtained by a bootstrap-mediated implementation of Moore and Flanner's difference factor ( f 2). The same conclusion was reached employing an f 2-based comparison, despite its inability to differentiate between polymorphs II and III. Therefore, PCA-CR may be considered a complementary and useful tool for probing the polymorphic form present in a pharmaceutical formulation.

Simultaneous determination of uranium carbide dissolution products by capillary zone electrophoresis

Separation and simultaneous determination of a number of organic acid anions (oxalate, mellitate, trimellitate and benzoate) and U(VI) with direct UV detection is developed for analysis of uranium carbide (UC) dissolution products by capillary zone electrophoresis (CZE). Reverse polarity mode is used. It is found that complex formation of U(VI) with carbonate, used as a carrier electrolyte, allows U(VI) to be determined, as negatively charged species, in a single run with organic acid anions. Some parameters such as pH value, composition of electrolyte and detection wavelength are optimized. Under the chosen conditions (carbonate buffer (ionic strength of 100 mM), pH 9.8, 0.15 mM tetradecyltrimethylammonium bromide (TTAB)) a complete separation is achieved. Calibration plots are linear in two ranges of concentration for U(VI) (∼1 × 10 −5 to 1 × 10 −3), mellitate and trimellitate (∼5 × 10 −6 to 5 × 10 −4), and about one range (∼1 × 10 −4 to 5 × 10 −3) for oxalate and benzoate. Accuracy of the procedure is checked by the “added-found” method in standard mixture solutions. Relative standard deviation is within the range of 2–10% and the recovery is in the range of 90–110%. This method is applied for the analysis of real UC dissolution samples.

Calorimetric study of dissolution kinetics of phosphorite in diluted acetic acid

In this report, we present a thermodynamic and kinetic study of the selective dissolution of calcite from low-grade phosphate ores (Epirus area, Greece) by dilute acetic acid at isothermal conditions. A twin calorimeter with two identical membrane vessels, for the acid dissolution process, and for the reference was used. The curves of rate vs. time of the phosphorite dissolution for various temperatures show that the maximum (.qmax) was increased, whereas the time (tpeak) to achieve the corresponding .qmax values was decreased, as the experimental temperature was increased. The dissolution enthalpy was increased from 13.1 to 16.7 kJ mol−1, as the experimental temperature was increased from 10.0 to 28.0°C. The chemical analysis of the supernatant solutions shows that the main process was the calcite dissolution. The reaction model with general form, ln(1/(1-X))=ktm, was found to fitted the experimental data regardless of the experimental temperature. These results were assigned in the presence of two different kinds of particles in the phosphorite. The activation energy of the dissolution process was found 69.7 kJ mol−1. The SEM micrographs of acid dissolution samples showed two different textures after acid dissolution.

Rapid releases of metal salts and nutrients following the deposition of volcanic ash into aqueous environments

Deposition of volcanic ash into aqueous environments leads to dissolution of adsorbed metal salts and aerosols, increasing the bioavailability of key nutrients. Volcanogenic fertilization events could increase marine primary productivity, leading to a drawdown of atmospheric CO 2. Here we conduct flow-through experiments on unhydrated volcanic ash samples from a variety of locations and sources, measuring the concentrations and fluxes of elements into de-ionized water and two contrasting ocean surface waters. Comparisons of element fluxes show that dissolution of adsorbed surface salts and aerosols dominates over glass dissolution, even in sustained low pH conditions. These surface ash-leachates appear unstable, decaying in situ even if kept unhydrated. Volcanic ash from recent eruptions is shown to have a large fertilization potential in both fresh and saline water. Fluorine concentrations are integral to bulk dissolution rates and samples with high F concentrations display elevated fluxes of some nutrients, particularly Fe, Si, and P. Bio-limiting micronutrients are released in large quantities, suggesting that subsequent biological growth will be limited by macronutrient availability. Importantly, acidification of surface waters and high fluxes of toxic elements highlights the potential of volcanic ash-leachates to poison aqueous environments. In particular, large pH changes can cause undersaturation of CaCO 3 polymorphs, damaging populations of calcifying organisms. Deposition of volcanic ash can both fertilize and/or poison aqueous environments, causing significant changes to surface water chemistry and biogeochemical cycles.

Development and validation of dissolution test for lopinavir, a poorly water-soluble drug, in soft gel capsules, based on in vivo data

The objective of the present study was to develop and validate a dissolution test for lopinavir soft gel capsules (Kaletra ®), using a simulated absorption profile based on in vivo data. Different conditions such as surfactant concentration, apparatus and rotation speed were evaluated. In vivo release profiles were obtained from the literature. The fraction (and percentage) of dose absorbed (FA) was calculated by using Wagner–Nelson method. The best in vitro dissolution profile was obtained using Apparatus 2 (paddle) at 25 rpm, 1000 ml of medium with 2.3% of sodium lauryl sulfate and pH 6.0. Under these conditions a level-A in vitro– in vivo correlation (IVIVC) was obtained ( r = 0.997). The in vitro dissolution samples were analyzed using a HPLC method and the validation was performed according to USP protocol. The method showed accuracy, precision, linearity and specificity within the acceptable range. Both the HPLC method and the in vitro dissolution method were validated and could be used to evaluate the release profile of lopinavir soft gel capsules.

Development and application of a validated HPLC method for the analysis of dissolution samples of gabapentin drug products

A simple isocratic reversed-phase HPLC method was developed and validated for the analysis of dissolution samples of gabapentin tablets and capsules. Separation of gabapentin from its major degradation impurity, 3,3-pentamethylene-4-butyrolactam was achieved on a Phenomenex Luna Cyano column using a methanol–acetonitrile–20 mM KH 2PO 4 (pH 2.2) (5:5:90, v/v/v) mobile phase. The compounds were eluted isocratically at a flow rate of 1.25 mL/min. Both compounds were analyzed with UV detection at 210 nm. The method was validated according to USP Category I requirements for gabapentin. The validation characteristics included accuracy, precision, linearity, range, specificity and limit of quantitation. Robustness testing was also conducted to evaluate the effect of minor changes to the chromatographic system and to establish appropriate system suitability parameters. Validation acceptance criteria were met in all cases. This method was used successfully for the quality assessment of five gabapentin drug products.

Effect of five Alive&amp;#174 fruit juice on the dissolution and absorption profiles of ciprofloxacin

To determine the effect of interaction of five Alive fruit juice on the dissolution and absorption profiles of ciprofloxacin tablets using urinary excretion. In-vitro dissolution of ciprofloxacin 500 mg tablets was studied using US Pharmacopoeia dissolution apparatus II. This was conducted using 0.1N HCl and equal volumes of the fruit juice and 0.1N HCL. Samples were collected at predetermined time intervals for two hours. For the in-vivo study, eleven (5 males and 6 females) healthy volunteers participated in an open, single dose, cross-over randomized trial. After an overnight fasting, each volunteer either ingested a 500 mg ciprofloxacin tablet with 250 ml table water or with the fruit juice. Total urine voided was collected for 72 hrs after each dose of ciprofloxacin. Dissolution and urine samples were assayed using a controlled and validated UV spectrophotometric analysis. A lag time of 5 minutes was observed in dissolution profile of ciprofloxacin in the juice. The percent dissolved of ciprofloxacin in 0.1NHCl and fruit juice were found to be dissimilar (f2 =18.2) using similarity factor. There was statistical difference between the K(el) (elimination constant), K(e) (excretion rate) and X(u) (cumulative amount excreted unchanged) of subjects on water (0.1759 +/- 0.0144; 12.81 +/- 1.36; 375.5 +/- 41.2) and that of fruit juice (0.1250 +/- 0.0161; 7.6 +/- 1.07; 241.6 +/- 34.0). However, there was no difference between the t(1/2) of the subjects (4.2 +/- 0.3; 5.5 +/- 0.8). There was a decrease in relative availability of the drug by 35.75%. We conclude that the absorption of ciprofloxacin can be reduced by concomitant ingestion of the juice containing calcium carbonate and grape. Therefore to avoid drug therapeutic failures and subsequent bacterial resistance as a result of subtherapeutic level of the drug in the systemic circulation, ingestion of the juice with ciprofloxacin should be discouraged.

Sensitive HPTLC method for monitoring dissolution profiles of diclofenac from different tablets containing combined diclofenac and acetaminophen

Two fundamentally different analytical methods have been validated and used to monitor release of diclofenac and acetaminophen (paracetamol), from commercially available combination tablet formulations, in dissolution media. A sensitive HPTLC method was developed and validated for analysis of diclofenac. The filtered dissolution samples were directly spotted on to precoated silica gel 60 F 254 TLC plates and diclofenac was separated by use of chloroform-methanol-ammonia solution, 10 + 25 + 0.25 ( v/v ), as mobile phase. The spots were scanned at λ = 277 nm. Peak areas for diclofenac were found to be linearly dependent on the amount applied to the plate in the range 30–390 ng spot −1 ( r = 0.999).For estimation of acetaminophen a simple colorimetric method, involving reaction with sodium nitrite in acid then treatment with alkali to produce the 3-nitroacetaminophane anion (yellow color), was validated and used. The intensity of the yellow color, monitored at λ = 430 nm, was found to be linearly dependent o...