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EN
Lacosamide, a new type of antiepileptic drug, was subjected to forced degradation under the conditions of hydrolysis (acidic and alkaline), oxidation, dry heat, and photolysis to characterize its possible degradation products. The drug showed significant degradation under acidic, alkaline and oxidative conditions. The degradation products were separated on an Agilent Zorbax SB-C18 column with gradient elution using a mobile phase consisting of acetonitrile and ammonium acetate (0.002 mol/L) with formic acid as additive. A combination of liquid chromatography hybrid triple quadrupole-linear ion trap mass spectrometry (LC–QqLIT-MS) and liquid chromatography hybrid ion trap/time-of-flight mass spectrometry (LC-IT/TOF-MS) was used to identify degradation products. A total of 7 products including 4 novel degradation products were characterized. The mechanisms of degradation products of lacosamide were discussed. Application of the method to study degradation products of lacosamide provided fragment information, allowing further investigation of the degradation pathways and intrinsic stability of the drug.
EN
A gradient reversed phase high-performance liquid chromatography (RP-HPLC) method with ultraviolet (UV) detection to analyze hydrochlorothiazide (HCT) and valsartan (VS) simultaneously in a tablet formulation during forced degradation studies was developed. This method was validated using a novel approach, namely, the accuracy profile or total errors approach. The robustness of the method was evaluated using a Plackett-Burman design for eight factors. The algorithm of Dong was applied to determine the significant factor effects. The validation results showed that the method is precise (RSD: 1.14% for HCT and 0.43% for VS) and accurate (mean recovery: 99.90% for HCT and 99.98% for VS). On the other hand, the results of the robustness study showed that the type of column was the important factor which affects a number of responses, namely, the asymmetry factor (AF), retention time (RT), and resolution (RS). However, the assay results were not affected; therefore, the method can be considered robust. Finally, the method was applied to study the stability of HCT and VS under forced conditions. Significant results were obtained with basic hydrolysis, oxidation, and thermal stress, while the accelerated and acidic conditions did not affect the stability of HCT or VS.
3
Content available remote Stress degradation studies on zolpidem tartrate using LC-DAD and LC-MS methods
EN
The present study was designed to characterize the possible degradation products of zolpidem tartrate under various stress conditions according to International Conference on Harmonization (ICH) guidelines Q1A(R2). After exposure to light, heat, hydrolysis, and oxidation, the drug significantly degraded under photolytic and acid/base hydrolytic conditions. Degradation resulted in the formation of four key degradants. Degradation products were resolved from each other and the drug by employing an isocratic elution method on Luna C18 column with mobile phase consisting of methanol-10 mM ammonium acetate (68.4:31.6, v/v), wherein pH was adjusted to 5.4 with glacial acetic acid. To characterize the degradation products, a method was extended to LC-MS and a mass fragmentation pattern was established using single quadrupole. The degradants were identified as zolpacid, oxozolpidem, zolpaldehyde, and zolpyridine. Finally, the most possible degradation mechanism of zolpidem tartrate in different environments was proposed.
EN
The objective of the present investigation was to develop and validate a stability indicating liquid chromatography (LC) method which should possess potential to separate flucloxacillin as well as all the degradation products. Simultaneously, our aim was also to identify, separate, and characterize the major degradation product (DPs) of flucloxacillin, generated under various stress conditions. To achieve this objective, flucloxacillin was subjected to hydrolytic, oxidative, photolytic, and thermal stress as per International Conference on Harmonization (ICH) guidelines Q1A(R2). The drug was found to degrade in acidic, alkaline, neutral, and oxidative stress conditions and showed stable behavior in photolytic and thermal stress conditions. In total, seven degradation products were formed, which were separated on a C-18 column employing a gradient high-performance liquid chromatographic (HPLC) method. A complete mass fragmentation pathway of the drug was established with the help of multi-stage (MSn) and mass spectrometry/time of flight (MS/TOF) accurate mass studies. Then the stress samples were subjected to LC-MS/TOF studies, which provided the fragmentation pattern along with the accurate masses for a major degradation product. The entire mass spectral studies helped to identify the degradation product so as to propose its best possible structure. Finally the total information was used to establish the degradation pathway of the drug.
EN
A simple, selective, and stability-indicating reverse phase liquid chromatographic method has been developed and validated for the simultaneous determination of impurities and forced degradation products of quetiapine fumarate. The chromatographic separation was achieved on Inertsil-3 C8, 150 mm × 4.6 mm, 5 μm column at 35°C with UV detection at 217 nm using gradient mobile phase at a flow rate of 1.0 mL/min. Mobile phase A contains a mixture of 0.01 M di-potassium hydrogen orthophosphate (pH 6.8) and acetonitrile in the ratio of 80:20 (v/v), respectively, and mobile phase B contains a mixture of 0.01 M di-potassium hydrogen orthophosphate (pH 6.8) and acetonitrile in the ratio of 20:80 (v/v), respectively. The drug product was subjected to the stress conditions of oxidative, hydrolysis (acid and base), hydrolytic, thermal, and photolytic degradation. Quetiapine fumarate was found to degrade significantly in acid, base, and oxidative stress conditions. The degradation products were well resolved from main peak and its impurities. The mass balance was found to be in the range of 96.6–102.2% in all the stressed conditions, thus proved the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection and quantification, accuracy, precision, and robustness.
EN
An isocratic reversed-phase liquid chromatograpic assay method was developed for the quantitative determination of atorvastatin and aspirin (ASP) in combined dosage form. A Phenomenex Gemini C-18, 5-μm column with mobile phase containing 0.02 M potassium dihydrogen phosphate-acetonitrile-methanol (30:30:40, v/v/v) adjusted to pH 3 using o-phosphoric acid was used. The flow rate was 1.0 mL min -1 and effluents were monitored at 240 nm. The retention times (RTs) of atorvastatin calcium (ATV) and ASP were 10.5 and 3.8 min, respectively. ATV and ASP stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation, and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their RT values. Stressed samples were assayed using developed LC method. The proposed method was validated with respect to linearity, accuracy, precision, and robustness. The method was successfully applied to the estimation of ATV and ASP in combined capsule dosage forms.
EN
The objective of the current study is to develop a validated specific stability-indicating isocratic reversed-phase liquid chromatographic method for the quantitative determination of levofloxacin and its related substances in pharmaceutical dosage forms in the presence of degradation products and its process-related impurities. Forced degradation studies were performed on levofloxacin as per the International Conference on Harmonisation (ICH)-prescribed stress conditions using acid, base, oxidative, water hydrolysis, thermal stress and photolytic degradation to show the stability-indicating power of the method. Significant degradation was observed during oxidative stress; minor degradation was observed in acidic stress and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies and the spiked impurity solution. The analysis was carried out with a 50 mm length × 4.6 mm i.d., 3.0 μm particle size YMC Pack Pro-C18 column using the mobile phase consisting of a mixture of 1.0% (v/v) triethylamine in water with pH adjusted to 6.30, using orthophosphoric acid, methanol and acetonitrile (7.7:1.3:1.0) pumped at a flow rate of 0.8 mL min−1 with ultraviolet (UV) detection at 235 nm. The limit of detection and the limit of quantification for the levofloxacin and its process-related impurities were established. The stressed test solutions were assayed against the qualified working standard of levofloxacin and the mass balance in each case was in between 99.1% and 99.9%, indicating that the developed liquid chromatography (LC) method was a stability-indicating technique. Validation of the developed LC method was carried out as per ICH requirements.
EN
A new, sensitive, stability-indicating, and cost and time-effective isocratic reversed-phase UHPLC method has been developed for quantitative analysis of felbamate, an antiepileptic drug, both in the bulk drug and in pharmaceutical dosage forms. Chromatographic separation of felbamate and its two impurities was achieved on a C 18 column with a simple buffer-methanol mobile phase; the run time was 8 min. Quantification was achieved by ultraviolet detection. Resolution between the impurities was >2.0. Response was a linear function of concentration over the range 0.1–3.0 μg mL -1, correlation coefficient >0.999, for felbamate and the impurities. The method is capable of detecting the two impurities at levels of 0.002% (0.02 μg mL -1) of the test concentration of 1.0 mg mL -1 (1 μL injection). The same sensitivity was achieved for all the degradation products formed during stress studies in which the drug was subjected to hydrolysis, oxidation, photolysis, and thermal degradation. Substantial degradation occurred under acidic and basic conditions. The stressed test solutions were assayed against felbamate working standard and the mass balance in each case was close to 100%, indicating the method is stability-indicating. The method was validated for linearity, accuracy, precision, and robustness in accordance with ICH Guidelines.
EN
A novel stability-indicating LC assay method for quantitative determination oftadalafil in bulk drug and pharmaceutical dosage form in the presence of forced-degradation products was developed and validated. An isocratic reversed phase LC method was developed to separate the drug from its degradation products using a Zorbax SB-C18 column and water-acetonitrile mixture as a mobile phase. Detection was carried out at the wavelength of 235 nm. Tadalafil was subjected to stress conditions in order to perform its hydrolytic (acid, base), oxidative, photolytic, and thermal degradation. Degradation oftadalafil was observed in the presence of acid, base, and 30% H2O2. The drug was found to be stable under other stress conditions. The signals of degradation products were well-resolved from the main peak oftadalafil. Percentage recovery oftadalafil in pharmaceutical dosage form ranged from 98.89% to 101.25%. The developed method was validated with respect to linearity, accuracy (recovery), precision, specificity, and robustness. Forced degradation studies proved the stability-indicating power of the method.
PL
Opracowano i zwalidowano nową metodę ilościowego oznaczania tadalafilu za pomocą chromatografii cieczowej, w obecności produktów rozkładu, pozwalającą na ocenę stabilności surowca i formy farmaceutycznej. Zastosowanie kolumny Zorbax SB-C18 i izokratycznej mieszaniny woda —acetonitryl pozwalało na rozdzielenie leku od produktów rozkładu. Detekcję przeprowadzono przy długości fali 235 nm. Tadalafil poddano ekstremalnym warunkom w celu uzyskania hydrolitycznych (kwas, zasada), oksydatywnych. tbtolitycznych i termicznych produktów rozkładu. Rozkład tadalafilu obserowwoano w obecności kwasów, zasad i 30% H,O2. Lek okazał się trwały w pozostałych ekstremalnych warunkach. Sygnały produktów rozkładu były dobrze oddzielone od głównego piku tadalafilu. Odzysk w przypadku badania postaci farmaceutycznej wynosił od 98,89% do 10 l ,25%. Opacowana. metodę zwalidowano w zakresie liniowości, dokładności (odzysku), precyzji, specyficzności i odporności na zmiany warunków otoczenia. Badania rozkładu w warunkach ekstremalnych wykazały przydatność opracowanej metody do oceny stabilności leku.
EN
A novel stability-indicating reversed-phase (RP) HPLC method has been developed and validated for quantitative analysis of eplerenone in the bulk drug and in a pharmaceutical dosage form. Use of a 250 mm × 4.6 mm, 5-μm particle, C18 column with 55:45 ( v/v ) 50 mM ammonium acetate buffer (pH 7)-acetonitrile as isocratic mobile phase enabled separation of the drug from its degradation products. UV detection was performed at 240 nm. The method was validated for linearity, accuracy (recovery), precision, specificity, and robustness. The linearity of the method was excellent over the range 10–100 μg mL -1 (correlation coefficient 0.999). The limits of detection and quantification were 0.019 and 0.053 μg mL -1, respectively. Recovery of eplerenone from the pharmaceutical dosage form ranged from 100.97 to 101.25%. Eplerenone was subjected to stress conditions (hydrolysis (acid, base), oxidation, photolysis, and thermal degradation) and the stressed samples were analysed by use of the method. Degradation was observed in acid, base, and 30% H 2 O 2 . The drug was stable under the other stress conditions investigated. The degradation products were well resolved from main peak. The forced degradation studies prove the stability indicating power of the method.
11
Content available remote RP-HPLC method for analysis of related substances in amoxicillin drug substance
EN
Linear gradient HPLC on a C 8 column has been used for separation of individual related substances of amoxicillin listed in the European Pharmacopoeia and a newly identified degradation impurity. The USP plate count for the amoxicillin peak was more than 3000 and USP tailing for the same peak was less than 2.0. Forced degradation studies were conducted on amoxicillin drug substance using ICH stress study guidelines to demonstrate the specificity and stability-indicating nature of the method. A new impurity observed after thermal and alkaline degradation was identified as N -pivaloylamoxicillin. The LOD and LOQ for individual related substances were below 0.045 and 0.086% ( w/w ), respectively. The method was fully validated in accordance with ICH analytical method validation guidelines. The results of the study prove the method is specific, precise, linear, robust, and can be used for evaluation of the stability of amoxicillin drug substance.
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