A Simple and Rapid Stability Indicating LC Determination of Ciprofloxacin Hydrochloride as a Bulk Drug and from Formulations

The present research work discusses the development of a stability indicating reversed phase LC method for determination of ciprofloxacin hydrochloride as a bulk drug and from formulations. The mobile phase selected was water-acetonitrile-triethylamine 75:25:0.1 (v/v/v) adjusted to pH 4.0 with o-phosphoric acid. The calibration curve of the drug was linear in the range 0.25–15 μg mL^?1. The method was accurate and precise with limits of detection and quantitation of 8.01 and 26.7 ng, respectively. Mean percent recovery was 100.71%. The method was used for analysis of ciprofloxacin hydrochloride from pharmaceutical formulations in the presence of its degradation products and commonly used excipients.     

Boronate-Containing Copolymer Grafted on Eupergit C as Matrix for Affinity Chromatography: Isotherms and Kinetics Study

A stability-indicating HPLC method has been developed and subsequently validated for the simultaneous determination of domperidone and pantoprazole in commercial tablets. The proposed HPLC method utilizes Phenomenex^® Gemini C₁₈ column (150 mm × 4.6 mm i.d., 5 μm) and mobile phase consisting of methanol-acetonitrile-20 mM dipotassium hydrogen phosphate and phosphoric acid buffer pH 7.0 (20:33:47, v/v/v) at a flow rate of 1.19 mL min^?1. Quantitation was achieved with UV detection at 285 nm based on peak area with linear calibration curves at concentration ranges 0.5–5.0 μg mL^?1 for domperidone and 1.0–10 μg mL^?1 for pantoprazole (R ² > 0.999 for both drugs). The method was validated in terms of accuracy, precision, linearity, limits of detection, limits of quantitation and robustness. This method has been successively applied to pharmaceutical formulation and no interference from the tablet excipients was found. Domperidone, pantoprazole and their combination drug product were exposed to acid, base and neutral hydrolysis, oxidation, dry heat and photolytic stress conditions and the stressed samples were analyzed by the proposed method. As the proposed method could effectively separate the drug from its degradation products, it can be employed as stability-indicating method for the determination of instability of these drugs in bulk and commercial products.     

A Stability Indicating LC Method for Deferasirox in Bulk Drugs and Pharmaceutical Dosage Forms

A novel, sensitive, stability indicating RP-LC method has been developed for the quantitative determination of deferasirox, its related impurities in both bulk drugs and pharmaceutical dosage forms. Efficient chromatographic separation was achieved on a C18 stationary phase with simple mobile phase combination delivered in an isocratic mode and quantitation was by ultraviolet detection at 245 nm. The mobile phase consisted of buffer, acetonitrile and methanol (50:45:5, v/v) delivered at a flow rate of 1.0 mL min^?1. Buffer consisted of 10 mM potassium dihydrogen orthophosphate monohydrate, pH adjusted to 3.0 by using orthophosphoric acid. In the developed LC method the resolution (R _s ) between deferasirox and its four potential impurities was found to be greater than 2.0. Regression analysis showed an r value (correlation coefficient) greater than 0.999 for deferasirox and its four impurities. This method was capable to detect all four impurities of deferasirox at a level of 0.002% with respect to test concentration of 0.5 mg mL^?1 for a 10 μL injection volume. The inter- and intra-day precision values for all four impurities and for deferasirox was found to be within 2.0% RSD. The method showed good and consistent recoveries for deferasirox in bulk drugs (98.3–101.1%), pharmaceutical dosage forms (100.2–103.1%) and for its all the four impurities (99.7–102.1%). The test solution was found to be stable in methanol for 48 h. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in acid stress hydrolysis. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.95%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.     

Enantiomeric Separation of Moxifloxacin and Its (R,R)-Isomer by Ligand-Exchange Chiral Chromatography

A new stereospecific LC method for the separation and quantification of moxifloxacin and its (R,R)-enantiomer in bulk drug was developed and validated by ligand-exchange liquid chromatography on a reversed phase column using aqueous mobile phase containing the chiral reagent l-isoleucine-Cu(II). The UV detector was operated at 293 nm. The flow rate of mobile phase was set at 0.9 mL min^?1. The achiral ODS column offers good separation of the two enantiomers in less than 20 min. The test concentration was 1,000 μg mL^?1 in the mobile phase. This method was capable of detecting the (R,R)-enantiomer of moxifloxacin up to 0.1 μg mL^?1 for a 20 μL injection volume. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. There was no interference of degradants with the (R,R)-enantiomer in the developed method. The developed chiral RP-LC method was validated with respect to linearity, accuracy, precision and robustness. The percentage recovery for the (R,R)-enantiomer in bulk drug samples ranged from 98.1 to 104.4%. The test solution was found to be stable in the mobile phase for 48 h after preparation.     

An Improved Narrow-Bore LC Method for Quantification of Alfuzosin in Pharmaceutical Formulations

A simple rapid and stability-indicating LC method using a narrow-bore column has been developed, fully validated, and applied to the quantification of alfuzosin in pharmaceutical formulations. Chromatography was achieved isocratically on a narrow-bore, 5-μm particle size, C₈ analytical column. The mobile phase was a 35:65 (v/v) 0.0125 m ammonium formate–acetonitrile at a flow rate of 0.35 mL min^?1. Detection was by UV absorption at 245 nm. Evaluation over the range 200–800 ng mL^?1 revealed linearity was good. Limits of detection and quantification for alfuzosin were 22.9 and 69.5 ng mL^?1, respectively. Intra-day and inter-day RSD were less than 6.4%, and the relative percentage error was less than ?1.7% (n = 5). Accelerated degradation performed under different stress conditions including oxidation, hydrolysis, and heat, proved the selectivity of the procedure. The method was successfully used for quality-control and content-uniformity testing of commercial tablets.     

Forced Degradation Study to Develop and Validate Stability-Indicating RP-LC for Quantification of Ropinirole Hydrochloride in Its Modified Release Tablets

A forced degradation study on ropinirole hydrochloride in bulk and in its modified release tablets was conducted under the conditions of hydrolysis, oxidation and photolysis in order to develop an isocratic stability-indicating LC-UV method for quantification of the drug in tablets. An impurity peak in standard solution was found to increase under acidic and neutral hydrolytic conditions while another degradation product was formed under alkaline condition. The drug and its degradation products were optimally resolved on a Hypersil C₁₈ column with mobile phase composed of diammonium hydrogen orthophosphate (0.05 M; pH 7.2), tetrahydrofuran and methanol (80:15:5% v/v) at a flow rate of 1.0 mL min^?1 at 30 °C using 250 nm as detection wavelength. The method was linear in the range of 0.05–50 μg mL^?1 drug concentrations. The %RSD of inter- and intra-day precision studies was <1. The system suitability parameters remained unaffected during quantification of the drug on three different LC systems. Excellent recoveries (101.59–102.28%) proved that the method was sufficiently accurate. The LOD and LOQ were found to be 0.012 and 0.040 μg mL^?1, respectively. Degradation behaviour of the drug in both bulk and tablets was similar. The drug was very unstable to hydrolytic conditions but stable to oxidative and photolytic conditions. The method can be used for rapid and accurate quantification of ropinirole hydrochloride in tablets during stability testing. Based on chemical reactivity of ropinirole in different media, the degradation products were suspected to be different from the known impurities of the drug.     

A Validated Stability Indicating LC Method for Mitotane in Bulk Drugs and Pharmaceutical Dosage Forms

A novel, sensitive, stability indicating RP-LC method has been developed for the quantitative determination of mitotane, its impurity in both bulk drugs and pharmaceutical dosage forms. Efficient chromatographic separation was achieved using a C18 stationary phase with simple mobile phase combination delivered in an isocratic mode and quantitation was by ultraviolet detection at a wavelength of 230 nm. The mobile phase consisted of buffer and acetonitrile (25:75, v/v) delivered at a flow rate of 1.0 mL min^?1. Buffer consisted of 10 mM potassium dihydrogen orthophosphate monohydrate, pH adjusted to 2.5 by orthophosphoric acid. In the developed LC method the resolution (R _s ) between mitotane and its impurity namely Imp-1 was found to be greater than 2.5. Regression analysis shows an r value (correlation coefficient) greater than 0.999 for mitotane and its impurity. This method was capable to detect the impurity of mitotane at a level of 0.003% with respect to test a concentration of 0.2 mg mL^?1 for a 10 μL injection volume. The inter- and intra-day precision values for mitotane and its impurity was found to be within 2.0% RSD. The method has shown good and consistent recoveries for mitotane in bulk drugs (99.2–101.5%), pharmaceutical dosage forms (98.2–103.1%) and for its impurity (99.7–102.1%). The test solution was found to be stable in diluent for 48 h. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in basic stress hydrolysis. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.97%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.     

Study of the Degradation Kinetics of Carvedilol by Use of a Validated Stability-Indicating LC Method

The objectives of this investigation were to establish a validated stability-indicating LC method for assay of carvedilol and to study the degradation behaviour of the drug under different ICH-recommended stress conditions. Chromatographic separation was achieved on a C₁₈ column with 55:45 (%, v/v) acetonitrile–0.02 m phosphate buffer, pH 3.5, as mobile phase at a flow rate of 1.0 mL min^?1; detection was by UV absorbance at 242 nm. The method was validated for linearity, precision, accuracy, robustness, specificity, and sensitivity, with the bulk drug. The drug was subjected to forced degradation and peaks of all the degradation products were well resolved from that of the pure drug, with significantly different retention times, which indicates the specificity and stability-indicating properties of the method. First-order degradation kinetics of carvedilol were observed under acidic and alkaline conditions. When the utility of the method was verified by analysis of the drug in marketed tablets and a nano-emulsion formulation, the assay was found to be 98.60–99.61 and 99.52–99.87, respectively. These results indicate the method can be successfully used for routine analysis of carvedilol in the bulk drug and in pharmaceutical dosage forms.     

A Stability-Indicating LC Method for Analysis of Balsalazide Disodium in the Bulk Drug and in Pharmaceutical Dosage Forms

A novel, sensitive, stability-indicating gradient RP-LC method has been developed for quantitative analysis of balsalazide disodium and its related impurities both in the bulk drug and in pharmaceutical dosage forms. Efficient chromatographic separation was achieved on a C₁₈ stationary phase with a simple mobile-phase gradient prepared from methanol and phosphate buffer (10 mm potassium dihydrogen orthophosphate monohydrate, adjusted to pH 2.5 by addition of orthophosphoric acid). The mobile-phase flow rate was 1.0 mL min^?1. Quantification was achieved by use of ultraviolet detection at 240 nm. Under these conditions resolution of balsalazide disodium from its three potential impurities was greater than 2.0. Regression analysis resulted in a correlation coefficient greater than 0.99 for balsalazide disodium and all three impurities. This method was capable of detecting the three impurities at 0.003% of the test concentration of 0.3 mg mL^?1, using an injection volume of 10 μL. Inter-day and intra-day precision for all three impurities and for balsalazide disodium was within 2.0% RSD. Recovery of balsalazide disodium from the bulk drug (99.2–101.5%) and from pharmaceutical dosage forms (99.8–101.3%), and recovery of the three impurities (99.1–102.1%) was consistently good. The test solution was found to be stable in 70:30 (v/v) methanol–water for 48 h. When the drug was subjected to hydrolytic, oxidative, photolytic, and thermal stress, acidic and alkaline hydrolysis and oxidizing conditions led to substantial degradation. The RP-LC method was validated for linearity, accuracy, precision, and robustness.     

Stability-Indicating LC Determination of a New Antihypertensive, Olmesartan Medoxomil in Tablets

A stability-indicating liquid chromatographic method was developed and validated for quantitative determination of olmesartan medoxomil (OLM) in coated tablets in the presence of degradation products generated under stress conditions. An isocratic LC separation was performed using a Phenomenex RP-18 column using a mobile phase consisting of water:triethylamine:acetonitrile (60:0.3:40 v/v/v, pH adjusted to 6.3 with phosphoric acid). The flow rate was 1.2 mL min^?1 and the detection was achieved with a photodiode array detector set at 257 nm. The response was linear over a range of 10.0 to 30.0 μg mL^?1 (r = 0.9999). The specificity and stability-indicating capability of the method was verified subjecting the reference substance and drug product to hydrolytic, oxidative, photolytic, and thermal stress conditions. The method showed a good and consistent recovery (100.2%) with low intra- and inter-day relative standard deviation (RSD) (≤1.0%). A considerable degradation occurred in all stress conditions and the degradation product was well resolved from the main peak. There was no interference of the excipients in the determination of the active pharmaceutical ingredient. Thus, the proposed method was found to be stability-indicating and can be used for routine analysis for quantitative determination of OLM in coated tablets without the interference of major degradation products.     

Stability-Indicating LC Method for Assay of Cholecalciferol

This paper discusses the development of a stability-indicating reversed-phase LC method for analysis of cholecalciferol as the bulk drug and in formulations. The mobile phase was acetonitrile–methanol–water 50:50:2 (v/v). The calibration plot for the drug was linear in the range 0.4–10 μg mL⁻¹. The method was accurate and precise with limits of detection and quantitation of 64 and 215 ng, respectively. Mean recovery was 100.71%. The method was used for analysis of cholecalciferol in pharmaceutical formulations in the presence of its degradation products and commonly used excipients.

     

Stability Indicating LC Assay Method for the Determination of Famciclovir in Bulk Drug and Pharmaceutical Dosage Forms

A simple isocratic stability indicating LC method was developed and validated for the determination of famciclovir in bulk drug and pharmaceutical dosage form. A mixture of 0.05 M potassium dihydrogen orthophosphate buffer and acetonitrile (80:20 v/v) was used as mobile phase at a flow rate of 1.0 mL min^?1. Hypersil BDS C18 (250 mm × 4.6 mm × 5 μm) column was used and the eluents were monitored at 220 nm. Forced degradation studies were performed for famciclovir active substance, reconstituted matrix and 500 mg tablets using the parameters like acid, base, peroxide, temperature, light, and relative humidity. Peak purity index was checked using PDA detection to demonstrate the specificity and stability indicating nature of the method. The developed method was validated for precision, ruggedness, linearity, LOD, LOQ, range, robustness and accuracy. The developed method can be used for regular quality control and stability study applications of famciclovir bulk drug and tablet dosage forms.     

Development and Validation of a New Analytical Method for the Determination of Related Components in Quetiapine Hemifumarate

A simple, sensitive isocratic rapid resolution liquid chromatographic assay method has been developed for the quantitative determination of quetiapine hemifumarate in bulk active pharmaceutical ingredient, used for the treatment of schizophrenia. The developed method is also applicable for the process related impurities determination. Efficient chromatographic separation was achieved on a C18 stationary phase with simple mobile phase combination delivered in a isocratic mode and quantification was by ultraviolet detection at 225 nm at a flow rate of 1.0 mL min^?1. In the developed LC method the resolution between quetiapine hemifumarate and its three potential impurities was found to be greater than 2.0. Regression analysis showed an r value (correlation coefficient) greater than 0.99 for quetiapine hemifumarate and its three impurities. This method was capable to detect all three impurities of quetiapine hemifumarate at a level of 0.003% with respect to test concentration of 1.0 mg mL^?1 for a 3 μL injection volume. The bulk active pharmaceutical ingredient was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in oxidative stress conditions. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.5%. The developed RR-LC method was validated with respect to linearity, accuracy, precision and robustness.     

A Stability-Indicating Assay of Brimonidine Tartrate Ophthalmic Solution and Stress Testing Using HILIC

A stability-indicating hydrophilic interaction liquid chromatography (HILIC) method has been developed and validated for the quantitative determination of Brimonidine tartrate (BT) formulated as an ophthalmic solution. Isocratic separation was achieved using an acetonitrile-buffer mixture (92:8, v/v) at pH 7.1 on an unmodified silica column (250 × 4.6 mm, 5 μm). The drug was subjected to oxidative, hydrolytic, photolytic and thermal stress conditions and complete separation was achieved for the parent compound and degradation products. The influence of acetonitrile, pH and ionic strength of the buffer was studied. Linearity range and recoveries for BT were 100–400 μg mL^?1 and 100.12%, respectively. The method was validated for BT and indicated that the method was sufficiently sensitive with a limit of detection at 0.005 μg mL^?1 and a limit of quantitation at 0.02 μg mL^?1, respectively.     

Stability-Indicating LC Method for the Determination of Olmesartan in Bulk Drug and in Pharmaceutical Dosage Form

A novel stability-indicating LC assay method was developed and validated for quantitative determination of olmesartan in bulk drugs and in pharmaceutical dosage form in the presence of degradation products generated from forced degradation studies. An isocratic, reversed phase LC method was developed to separate the drug from the degradation products, using an Ace5-C18 (250 mm × 4.6 mm, 5 μm) column, and 50 mM ammonium acetate (pH-5.5 by acetic acid) and acetonitrile (70:30 v/v) as a mobile phase. The detection was carried out at the wavelength of 235 nm. The olmesartan was subjected to stress conditions of hydrolysis (acid, base), oxidation, photolysis and thermal degradation. Degradation was observed for olmesartan in acid, base and in 30% H₂O₂ conditions. The drug was found to be stable in the other stress conditions attempted. The degradation products were well resolved from the main peak. The percentage recovery of olmesartan ranged from (99.89 to 100.95%) in pharmaceutical dosage form. The developed method was validated with respect to linearity, accuracy (recovery), precision, specificity and robustness. The forced degradation studies prove the stability-indicating power of the method.

     

LC-ESI-MS-MS Determination of Rat Plasma Protein Binding of Major Flavonoids of Flos Lonicerae Japonicae by Centrifugal Ultrafiltration

A simple, precise, accurate, selective, and sensitive reversed-phase LC–UV method has been developed for simultaneous analysis of diltiazem and non-steroidal anti-inflammatory drugs (NSAIDs) in the bulk drug, tablet dosage forms, and human serum. Chromatographic separation of the drugs was performed at ambient temperature on a C₁₈ stationary phase with 80:20 (v/v) methanol–water, pH 3.1 ± 0.02, as isocratic mobile phase. The mobile phase flow rate was initially 0.5 mL min^?1 then increased to 1 mL min^?1. All the NSAIDs were well separated from each other and from diltiazem. Total run time was 10 min. The assay was successfully applied to pharmaceutical formulations and serum and there was no chromatographic interference from tablet excipients. The method was linear in the range 1.25–50 μg mL^?1 both for diltiazem and the NSAIDs. The suitability of this HPLC method for quantitative analysis of the drugs was proved by validation in accordance with International Conference on Harmonization (ICH) guidelines. The validation results, and results from statistical analysis of the data, demonstrated the method was reliable.     

Stability-Indicating LC Method for the Determination of Lacidipine in Tablets. Application to Degradation Kinetics and Content Uniformity Testing

A simple, stability-indicating, reversed-phase liquid chromatographic method was developed for the determination of lacidipine in the presence of its degradation products. The analysis was carried out using a 150 mm × 4.6 mm i.d., 5 μm particle size Nucleodur MN-C18 column. Mobile phase containing a mixture of acetonitrile and 0.02 M phosphate buffer (70:30) at pH = 5.0 was pumped at a flow rate of 1 mL min^?1 with UV-detection at 254 nm. The method showed good linearity in the range of 0.06–15 μg mL^?1 with a limit of detection (S/N = 3) of 0.016 μg mL^?1 (3.5 × 10^?8 M). The suggested method was successfully applied for the analysis of lacidipine in bulk and in commercial tablets with average recoveries of 100.19 ± 0.81% and 100.05 ± 0.69%, respectively. The results were favorably compared to those obtained by a reference method. The suggested method was utilized to investigate the kinetics of alkaline, acidic, peroxide and photo-induced degradation of the drug. The apparent first-order rate constant, half-life times and activation energies of the degradation process were calculated. The pH profile curve was derived. The proposed method was successfully applied to the content uniformity testing of tablets.     

Stress Degradation Behavior of Entacapone and Development of LC Stability-Indicating Related Substances and Assay Method

A new, sensitive, stability indicating gradient RP-LC related substances and assay method has been developed for the quantitative determination of entacapone in bulk drugs. Efficient chromatographic separation was achieved on a C18 stationary phase with simple mobile phase combination of buffer and acetonitrile. Buffer consisted of 0.1% orthophosphoric acid, delivered in a gradient mode and quantitation was carried out using ultraviolet detection at 220 nm with a flow rate of 1.5 mL min^?1. In the developed LC method the resolution (R _s ) between entacapone and its three potential process impurities were found to be >2.0. Regression analysis showed an r ² value (correlation coefficient) >0.99 for entacapone and its three potential impurities. This method was capable to detect all three process impurities of entacapone at a level of 0.003% with respect to test concentration of 0.5 mg mL^?1 for a 20 μL injection volume. The inter- and intra-day precision values for all three impurities and for entacapone was found to be within 2.0% RSD. The method has shown good and consistent recoveries for entacapone in bulk drugs (99.2–101.5%) and its three impurities (99.5–102.2%). The test solution was found to be stable in diluent for 48 h. The drug substances were subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in acid stress, base stress and oxidative conditions. The stressed test solutions were assayed against the qualified working standard of entacapone and the mass balance in each case was close to 99.7% indicating that the developed method was stability-indicating. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.     

Stability-Indicating LC-PDA Method for Determination of Idebenone in Nanoparticles Based on Chitosan and N-Carboxymethylchitosan

A forced degradation study of idebenone was conducted under conditions of UV irradiation, acid, basic and oxidative hydrolysis and in order to develop an isocratic stability-indicating LC-UV method for drug quantification in chitosan and N-carboxymethylchitosan nanoparticles obtained by spray drying. The drug was more labile to alkaline treatment than under the other forced degradation conditions. Idebenone and its degradation products were optimally resolved (resolution >4) on a Luna Phenomenex C₁₈ column with mobile phase composed by methanol:water: (80:20% v/v) at a flow rate of 1.0 mL min^?1, at 30 °C, using wavelength of 279 nm for drug detection. The method was linear, over a drug concentration range of 2 to 10 μg mL^?1. The RSD% value of intra- and inter-day precision studies was <1.5. The method showed excellent recoveries (99.4 to 101.1%). The LOD and LOQ values were found to be 0.18 and 0.59 μg mL^?1, respectively. In conclusion this method can be used as a rapid and accurate assay of idebenone in the nanoparticles during stability tests.