A Stability Indicating LC Method for Vardenafil HCl

A simple, sensitive gradient RP-LC assay method has been developed for the quantitative determination of vardenafil HCl in bulk drug and in pharmaceutical dosage forms, used to treat erectile dysfunction. The developed method is also applicable for the related substances determination. Efficient chromatographic separation was achieved on a C18 stationary phase with simple mobile phase combination delivered in a gradient mode and quantification was carried out using ultraviolet detection at a flow rate of 1.0 mL min^?1. In the developed LC method the resolution between vardenafil and its four potential impurities was found to be greater than 3.0. Regression analysis shows an r ² value (correlation coefficient) greater than 0.99 for vardenafil and its four impurities. This method was capable of detecting all four impurities of vardenafil at a level of 0.009% with respect to test concentration of 1.0 mg mL^?1 for a 10 μL injection volume. The method has shown good and consistent recoveries for vardenafil (98.4–100.6%) and its four impurities (93.5–106.2%). The test solution was found to be stable in the diluent for 48 h. Mass balance was found close to 99.4%.     

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.     

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.     

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.     

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.

     

Development and Validation of a New Analytical Method for the Determination of Related Components and Assay of Ranolazine in Bulk Drug and Pharmaceutical Dosage Forms by LC

A novel liquid chromatographic method has been developed and validated for the determination of ranolazine, its potential four impurities in drug substance and drug products. Efficient chromatographic separation was achieved on a C18 stationary phase (150 × 4.6 mm, 3.0 microns particles) with simple mobile phase combination delivered in gradient mode at a flow rate of 1.0 mL min^?1 at 210 nm. In the developed method, the resolution between ranolazine and its four potential impurities was found to be greater than 2.0. Regression analysis shows an r value (correlation coefficient) greater than 0.999 for ranolazine and for its four impurities. This method was capable to detect all four impurities of ranolazine at a level below 0.004% with respect to test concentration of 1.0 mg mL^?1 for a 10 μL injection volume. The method has shown good, consistent recoveries for ranolazine (98.8–101.1%) and for its four impurities (97.2–100.3). The test solution was found to be stable in the diluent for 48 h. The drug was subjected to stress conditions. The mass balance was found close to 99.5%.     

Simultaneous Determination of Etodolac and Acetaminophen in Tablet Dosage Form by RP-LC

A simple, specific, precise and accurate reverse phase liquid chromatographic (RP-LC) method has been developed for the simultaneous determination of etodolac and acetaminophen in tablet dosage form. The chromatographic separation was achieved on a BDS Hypersil C18, 100 mm × 4.6 mm, 5 μm column at a detector wavelength of 274 nm using an isocratic mobile phase consisting of a mixture of 0.05% aqueous orthophosphoric acid and acetonitrile in the ratio of 50:50 (v/v) at a flow rate of 1.0 mL min^?1. The retention times for etodolac and acetaminophen were found to be 1.32 and 4.24 min, respectively. The method was validated for the parameters like specificity, linearity, precision, accuracy and robustness. The method was found to be specific and stability indicating as no interfering peaks of impurities, degradent and excipients were observed. The square of correlation coefficients (R ²) for etodolac and acetaminophen were 0.9996 and 0.9998 while percentage recoveries were 101.32 and 100.94%, respectively. Intra- and inter-day relative standard deviations for both the components were <2.0%. The proposed RP-LC method can be applied for the routine analysis of commercially available formulations of these drugs either as such or in combination.     

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.

     

Stress Degradation Behavior of Desipramine Hydrochloride and Development of Suitable Stability-Indicating LC Method

A simple reverse phase liquid chromatographic method was developed for the quantitative determination of desipramine hydrochloride and its related impurities in bulk drugs which is also stability-indicating. During the forced degradation at hydrolysis, oxidative, photolytic and thermal stressed conditions, the degradation results were only observed in the oxidative stress condition. The blend of the degradation product and potential impurities were used to optimize the method by an YMC Pack Pro C₁₈ stationary phase. The LC method employs a linear gradient elution with the water–acetonitrile–trifluoroacetic acid as mobile phase. The flow rate was 1.0 mL min^?1 and the detection wavelength 215 nm. The stressed samples were quantified against a qualified reference standard and the mass balance was found close to 99.0% (w/w) when the response of the degradant was considered to be equal to the analyte (i.e. desipramine). The developed RP-LC method was validated in agreement with ICH requirements.     

Development of the HPLC Method for Simultaneous Determination of Lidocaine Hydrochloride and Tribenoside Along with Their Impurities Supported by the QSRR Approach

A new liquid chromatographic (LC) method for simultaneous determination of lidocaine hydrochloride (LH) and tribenoside (TR) along with their related compounds in pharmaceutical preparations is described. Satisfactory LC separation of all analytes after the liquid–liquid extraction (LLE) procedure with ethanol was performed on a C₁₈ column using a gradient elution of a mixture of acetonitrile and 0.1 % orthophosphoric acid as the mobile phase. The procedure was validated according to the ICH guidelines. The limits of detection (LOD) and quantification (LOQ) were 4.36 and 13.21 μg mL^?1 for LH, 7.60 and 23.04 μg mL^?1 for TR, and below 0.11 and 0.33 μg mL^?1 for their impurities, respectively. Intra- and inter-day precision was below 1.97 %, whereas accuracy for all analytes ranged from 98.17 to 101.94 %. The proposed method was sensitive, robust, and specific allowing reliable simultaneous quantification of all mentioned compounds. Moreover, a comparative study of the RP-LC column classification based on the quantitative structure-retention relationships (QSRR) and column selectivity obtained in real pharmaceutical analysis was innovatively applied using factor analysis (FA). In the column performance test, the analysis of LH and TR in the presence of their impurities was carried out according to the developed method with the use of 12 RP-LC stationary phases previously tested under the QSRR conditions. The obtained results confirmed that the classes of the stationary phases selected in accordance with the QSRR models provided comparable separation for LH, TR, and their impurities. Hence, it was concluded that the proposed QSRR approach could be considered a supportive tool in the selection of the suitable column for the pharmaceutical analysis.     

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.     

Simultaneous Determination of Impurities in Ropinirole Tablets by an Improved HPLC Method Coupled with Diode Array Detection

A gradient HPLC method coupled with diode array detection was developed and fully validated for the analysis of impurities in ropinirole using a Kromasil^® C8 100 Å (250 × 4.6 mm, 5 μm) column with a flow rate 1.0 mL min^?1 and detection at 250 nm. The mobile phase component A consisted of a mixture of 19.6 mM aqueous potassium dihydrogen phosphate–acetonitrile (98:2 v/v), pH adjusted to 7.0 with triethylamine and the mobile phase component B consisted of acetonitrile. The method was validated in terms of linearity, sensitivity, precision, accuracy and stability. The calibration curves for ropinirole and its five impurities showed good linearity (r > 0.998) within the calibration ranges tested. The intra- and inter-day RSD values were <3.9 %, while the relative percentage error E _r was <5.8 % for all compounds. Accelerated stability studies performed under various stress conditions including oxidation, hydrolysis and UV light irradiation at 254 nm proved the selectivity of the procedure. Long-term stability studies performed on blistered tablets and under various conditions of heat and humidity indicate the presence of four of the studied impurities in less than 0.07 %. The method was applied successfully to the detection and determination of ropinirole impurities in pharmaceutical formulations.     

A Stability Indicating LC Method for Amtolmetin Guacyl

A simple, sensitive gradient RP-LC assay method has been developed for the quantitative determination of amtolmetin guacyl in bulk drug, used as anti-inflammatory drug. The developed method is also applicable for related substances determination. Efficient chromatographic separation was achieved on a C18 stationary phase with simple mobile phase combination delivered in a gradient mode and quantification was carried out using ultraviolet detection at 313 nm at a flow rate of 1.0 mL min^?1. In the developed LC method the resolution between Amtolmetin Guacyl and its three potential impurities was found to be greater than 2.0. Regression analysis shows an r value (correlation coefficient) greater than 0.99 for amtolmetin guacyl and its three impurities. This method was capable to detect all three impurities of amtolmetin guacyl 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 three impurities and for amtolmetin guacyl was found to be within 2.0% RSD at its specification level. The method has shown good and consistent recoveries for amtolmetin guacyl (99.2–101.5%) and its three impurities (94.5–104.8%). 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 oxidative stress conditions. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.6%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.     

Development and Validation of a New Analytical Method for the Determination of Related Components in Tolterodine Tartarate Using LC

A novel liquid chromatographic method has been developed, and validated for the determination of tolterodine tartarate, for its potential three impurities in drug substances and drug products. Efficient chromatographic separation was achieved on a C8 stationary phase (150 × 4.6 mm, 3.5 μm particles) with a simple mobile phase combination delivered in an isocratic mode at a flow rate of 0.8 mL min^?1 and quantitation was carried out using ultraviolet detection. Microwave assisted degradation procedure was employed for stress testing studies in addition to the conventional way of a refluxing method. The results of both studies were compared. In the developed LC method, the resolution between tolterodine and its three potential impurities was found to be greater than 2.0. Regression analysis shows an r value (correlation coefficient) greater than 0.999 for tolterodine and for its three impurities. This method was capable to detect all three impurities of tolterodine at a level below 0.0038% with respect to a test concentration of 0.5 mg mL^?1 for a 10 μL injection volume. The inter- and intra-day precisions for all three impurities and for tolterodine were found to be within 1.1% RSD at its specification level. The method has shown good, consistent recoveries for tolterodine (98.9–101.6%) and for its three impurities (94.5–103.0%). The test solution was found to be stable in the diluent for 48 h. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation, as prescribed by ICH. Degradation was found to occur in alkaline stress condition, while the drug was stable to water hydrolysis, acid hydrolysis, oxidative stress, photolytic and thermal stress. The assay of stressed samples was calculated against a qualified reference standard and the mass balance was found close to 99.5%. Microwave degradations were very fast and comparable to the conventional way of the refluxing method. Robustness studies were carried out and suggested that system suitability parameters were unaffected by small changes in critical factors. The validated method was successfully applied for the determination of tolterodine tartarate in drug substances and drug products.     

Development and Validation of a New LC Method for Analysis of Brimonidine Tartrate and Related Compounds

A novel liquid chromatographic method for analysis three potential impurities in brimonidine tartrate drug substance has been developed and validated. Efficient chromatographic separation was achieved on a C₈ column (250 mm × 4.6 mm, 5-μm particles) with a simple mobile-phase gradient at a flow rate of 1.0 mL min^?1. Quantification was achieved by use of ultraviolet detection at 248 nm. Resolution between brimonidine tartrate and its three potential impurities was greater than 3.0. Regression analysis showed the r value (correlation coefficient) was >0.999 for brimonidine and its three impurities. The method was capable of detecting all three impurities of brimonidine tartrate at levels below 0.07 μg in a test concentration of brimonidine tartrate of 1.0 mg mL^?1 and for an injection volume of 10 μL. A solution of brimonidine tartrate in acetonitrile–water 2:8 (v/v) was stable for 48 h. The drug was subjected to stress conditions as prescribed by the ICH. Degradation was found to occur slightly under oxidative stress conditions but the drug was stable to aqueous, acidic, and basic hydrolysis, and photolytic and thermal stress. The assay of the stressed samples was calculated relative to a qualified reference standard and the mass balance was found close to 99.8%. The method was validated for linearity, accuracy, precision, and robustness.     

Development of a New Analytical Method for Determination of Related Components in Nateglinide

An isocratic reverse phase liquid chromatographic (RP-LC) assay method has been developed for the quantitative determination of nateglinide and its related components namely imp-1 and imp-2 in bulk drug and in pharmaceutical dosage form, used for the treatment of type II diabetes mellitus. The developed method is stability indicating and also can be used for stability testing. The chromatographic separation was achieved on C-8, 150 × 4.6 mm, 3.5 μm stationary phase. The LC method employs solution A as mobile phase. Solution A contains a mixture of phosphate buffer pH 3.0: acetonitrile (50:50 v/v). The flow rate was 1.0 mL min⁻¹ and the detection wavelength was 210 nm. In the developed LC method the resolution between nateglinide and its potential impurities namely imp-1 and imp-2 was found to be greater than 5.0. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in acid medium, alkaline medium and oxidative stress conditions. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.2%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.     

Development and Validation of a Novel Stability Indicating UPLC <Emphasis Type="SmallCaps">M</Emphasis>ethod for Analysis of Related Compounds and Assay of Bexarotene,an Anti-Cancer Agent

A novel liquid chromatographic method for the analysis of four potential impurities in the anti-cancer agent Bexarotene has been developed and validated using efficient chromatographic separation, achieved on a C₁₈ column (50 mm × 2.1 mm, 1.7-μm particles) with a simple isocratic mobile phase at a flow rate of 0.5 mL min^?1. The mobile phase consisted of a 70:30:0.1 (v/v/v) mixture of acetonitrile, water and trifluoroacetic acid, and quantification was achieved by use of ultraviolet detection at 260 nm. Resolution between Bexarotene and its four potential impurities was greater than 2.0. Regression analysis showed the r value (correlation coefficient) was >0.999 for Bexarotene and its four impurities. The method was capable of detecting all four impurities of Bexarotene at levels below 0.10 μg in a Bexarotene test concentration of 0.5 mg mL^?1 using an injection volume of 5 μL. The recovery for Bexarotene in assay method at a 100% level was observed to be 99.1 ± 0.32% with % RSD value of 0.5% for drug substance and 98.9 ± 0.46% for Bexarotene capsules with % RSD value of 0.4%. Recovery of imp-1, imp-2, imp-3, and imp-4 from bulk drug samples ranged from 96.3 to 102.0%. Recovery of imp-1, imp-2, imp-3, and imp-4 from Bexarotene Capsule samples ranged from 97.2 to 101.4%. A solution of Bexarotene in ethanol was stable for 48 h. The drug was also subjected to stress conditions as prescribed by ICH Guidelines. Degradation was found to occur under acidic and basic hydrolysis stress conditions; however, the drug was stable to oxidative, photolytic, and thermal stress. Assay of the stressed samples was calculated relative to a qualified reference standard and the mass balance was found to be close to 99.8%. The method was validated for linearity, accuracy, precision, and robustness.     

Stress Degradation Behavior of Desipramine Hydrochloride and Development of Suitable Stability-Indicating LC Method

A simple reverse phase liquid chromatographic method was developed for the quantitative determination of desipramine hydrochloride and its related impurities in bulk drugs which is also stability-indicating. During the forced degradation at hydrolysis, oxidative, photolytic and thermal stressed conditions, the degradation results were only observed in the oxidative stress condition. The blend of the degradation product and potential impurities were used to optimize the method by an YMC Pack Pro C₁₈ stationary phase. The LC method employs a linear gradient elution with the water–acetonitrile–trifluoroacetic acid as mobile phase. The flow rate was 1.0 mL min⁻¹ and the detection wavelength 215 nm. The stressed samples were quantified against a qualified reference standard and the mass balance was found close to 99.0% (w/w) when the response of the degradant was considered to be equal to the analyte (i.e. desipramine). The developed RP-LC method was validated in agreement with ICH requirements.

     

Development and Validation of a Stability-Indicating LC Method for the Determination of Rupatadine in Pharmaceutical Formulations

A reversed-phase liquid chromatography (RP-LC) method was validated for the determination of rupatadine in pharmaceutical dosage forms. The LC method was carried out on a Gemini C₁₈ column (150 mm × 4.6 mm I.D.), maintained at 30 °C. The mobile phase consisted of ammonium acetate buffer (pH 3.0; 0.01 M) with 0.05% of 1-heptanesulfonic acid–acetonitrile (71.5:28.5, v/v), run at a flow rate of 1.0 mL min^?1 and using photodiode array (PDA) detection at 242 nm. The chromatographic separation was obtained with retention time of 5.15 min, and was linear in the range of 0.5–400 μg mL^?1 (r ² = 0.9999). The specificity and stability-indicating capability of the method was proven through the degradation studies and showing also, that there was no interference of the excipients. The accuracy was 100.39% with bias lower than 0.58%. The limits of detection and quantitation were 0.01 and 0.5 μg mL^?1, respectively. Moreover, method validation demonstrated acceptable results for precision, sensitivity and robustness. The proposed method was applied for the analysis of pharmaceutical dosage forms assuring the therapeutic efficacy.     

Simultaneous Determination of Clobetasol Propionate and Calcipotriol in a Novel Fixed Dose Emulgel Formulation by LC-UV

A new, rapid, selective, cheap and simple RP-LC method has been developed and validated for the simultaneous determination of clobetasol propionate and calcipotriol mixtures in bulk drugs (raw materials) and in a novel-fixed dose emulgel formulation. Separation was carried out using a NovaPak C18 column with methanol:water (74:26 v/v) as mobile phase for isocratic elution at a flow rate of 1.0 mL min^?1. The column temperature was set at 25 °C. Calibration curves were established ranging between 0.5 and 20 μg mL^?1 and 0.5 and 10 μg mL^?1 for clobetasol propionate and calcipotriol, respectively. Limit of detection and limit of quantification values of the method was found as 0.16 and 0.48 μg mL^?1 for clobetasol propionate and 0.10 and 0.30 μg mL^?1 for calcipotriol, respectively. The method was validated in accordance with ICH guidelines and obtained results proved that the proposed method was precise, accurate, selective and sensitive for the simultaneous analysis of clobetasol propionate and calcipotriol. The proposed method can be easily applied for the simultaneous determination of clobetasol propionate and calcipotriol in prepared emulgel formulations. The obtained validation results showed that the RP-LC method is suitable for routine quantification of clobetasol propionate and calcipotriol in emulgel formulations with high precision and accuracy.