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1.  Development and Validation of a Rapid RP-UPLC Method for the Simultaneous Estimation of Bambuterol Hydrochloride and Montelukast Sodium from Tablets 
A rapid, simple, sensitive and selective analytical method was developed by using reverse phase ultra performance liquid chromatographic technique for the simultaneous estimation of bambuterol hydrochloride and montelukast sodium in combined tablet dosage form. The developed method is superior in technology to conventional high performance liquid chromatography with respect to speed, resolution, solvent consumption, time, and cost of analysis. Elution time for the separation was 6 min and ultra violet detection was carried out at 210 nm. Efficient separation was achieved on BEH C18 sub-2-μm Acquity UPLC column using 0.025% (v/v) trifluoro acetic acid in water and acetonitrile as organic solvent in a linear gradient program. Resolutions between bambuterol hydrochloride and montelukast sodium were found to be more than 31. The active pharmaceutical ingredient was extracted from tablet dosage from using a mixture of methanol, acetonitrile and water as diluent. The calibration graphs were linear for bambuterol hydrochloride and montelukast sodium in the range of 6.25-37.5 μg/ml. The percentage recoveries for bambuterol hydrochloride and montelukast sodium were found to be in the range of 99.1-100.0% and 98.0-101.6%, respectively. The test solution was found to be stable for 7 days when stored in the refrigerator between 2-8°. Developed UPLC method was validated as per International Conference on Harmonization specifications for method validation. This method can be successfully employed for simultaneous estimation of bambuterol hydrochloride and montelukast sodium in bulk drugs and formulations.
doi:10.4103/0250-474X.103841
PMCID: PMC3546327  PMID: 23325991
Bambuterol hydrochloride; column liquid chromatography; montelukast sodium; Ultra Performance Liquid Chromatography (UPLC); validation and simultaneous estimation
2.  Development and Validation of an Ultra Performance Liquid Chromatography Method for Venlafaxine Hydrochloride in Bulk and Capsule Dosage Form 
A simple, specific, accurate, and precise ultra performance liquid chromatographic method was developed and validated for the estimation of venlafaxine hydrochloride in tablet dosage forms. A acquity TM BEH column having C18, 100×2.1 mm i.d. in isocratic mode, with mobile phase containing dipotassium hydrogen phosphate: Acetonitrile (30:70 v/v; pH 7.00 with dilute o-phosphoric acid) was used. The flow rate was 0.75 ml/min and effluents were monitored at 227 nm. The retention time of venlafaxine hydrochloride was 0.548 min. The method was validated for specificity, linearity, accuracy, precision, limit of quantification, limit of detection, robustness and solution stability. Limit of detection and limit of quantification for estimation of venlafaxine hydrochloride were found to be 6.11 μg/ml and 20.33 μg/ml, respectively. Recoveries of venlafaxine hydrochloride in tablet formulations were found to be in the range of 99.3-99.5%. Proposed method was successfully applied for the quantitative determination of venlafaxine hydrochloride in tablet dosage forms.
doi:10.4103/0250-474X.84605
PMCID: PMC3178991  PMID: 21969762
UPLC; validation; venlafaxine hydrochloride
3.  Stability-indicating RP-HPLC Method for the Simultaneous Determination of Sitagliptin and Simvastatin in Tablets 
A new stability-indicating high-performance liquid chromatographic method for simultaneous analysis of sitagliptin and simvastatin in pharmaceutical dosage form was developed and validated. The mobile phase consisted of methanol and water (70:30, v/v) with 0.2 % of n-heptane sulfonic acid adjusted to pH 3.0 with ortho phosphoric acid was used. Retentions of sitagliptin and simvastatin were 4.3 min and 30.4 min, respectively with a flow rate of 1 ml/min on C8 (Qualisil BDS, 250×4.6 mm, 5 μ). Eluents were detected at 253 nm using photodiode diode array detector. The linear regression analysis data for the linearity plot showed correlation coefficient values of 0.9998 and 0.9993 for sitagliptin and simvastatin, with respective concentration ranges of 20-150 μg/ml and 8-60 μg/ml. The relative standard deviation for inter-day precision was lower than 2.0%. The assay of sitagliptin and simvastatin was determined in tablet dosage form was found to be within limits. Both drugs were subjected to a variety of stress conditions such as acidic, basic, oxidation, photolytic, neutral and thermal stress in order to achieve adequate degradation. Results revealed that considerable degradation was found in all stress conditions except oxidative degradations. The method has proven specificity for stability indicating assay method.
PMCID: PMC4243257  PMID: 25425754
Sitagliptin; simvastatin; reverse phase liquid chromatography
4.  Liquid Chromatographic Methods for the Determination of Vildagliptin in the Presence of its Synthetic Intermediate and the Simultaneous Determination of Pioglitazone Hydrochloride and Metformin Hydrochloride 
Two reversed-phase liquid chromatographic (RP-LC) methods are described for the determination of two binary mixtures of hypoglycemic agents. In the first method, vildagliptin (VDG) was determined in the presence of 3-amino-1-adamantanol (AAD), a synthetic intermediate and impurity of VDG. In the second method, pioglitazone hydrochloride (PGZ) and metformin hydrochloride (MET) were simultaneously determined in their binary mixture. Chromatographic separation in the two methods was achieved on a Symmetry® Waters C18 column (150 mm × 4.6 mm, 5 μm). In the first mixture, isocratic elution using a mobile phase of potassium dihydrogen phosphate buffer pH (4.6) - acetonitrile - methanol (30:50:20, v/v/v) at a flow rate of 1 mL min-1 with UV detection at 220 nm was performed. In the second method, isocratic elution based on potassium dihydrogen phosphate buffer pH (4.6) - acetonitrile (60:40, v/v) at a flow rate of 1 mL min-1 with UV detection at 210 nm was performed. Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 5-200 μg mL-1, 0.5-3 μg mL-1 and 10-150 μg mL-1 for VDG, PGZ and MET, respectively. The optimized methods were validated and proved to be specific, robust, precise and accurate for the quality control of the drugs in their pharmaceutical preparations.
PMCID: PMC3614836  PMID: 23675237
vildagliptin; pioglitazone hydrochloride; metformin hydrochloride; reversed-phase liquid chromatography; tablets
5.  Comparison between ultra-performance liquid chromatography with tandem mass spectrometry and a chemiluminescence immunoassay in the determination of cyclosporin A and tacrolimus levels in whole blood 
Regular immunosuppressant drug monitoring is important for maintaining the drug concentrations of organ recipients within the therapeutic range. The standardized liquid chromatography-tandem mass spectrometry (LC-TMS) technique has been used for the accurate analysis of immunosuppressive drugs. In the present study, the performance of the recently developed high-throughput, rapid ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-TMS) method was validated for the simultaneous measurement of cyclosporin A and tacrolimus in whole blood. The method of measuring cyclosporin A and tacrolimus using UPLC-TMS was established and the precision, limit of detection (LOD), limit of quantitation (LOQ) and matrix effect were validated. In addition, the performance of UPLC-TMS was compared with that of a chemiluminescence immunoassay (CLIA) in >3,400 clinical specimens. The UPLC-TMS revealed a within-run and between-run precision of <8% and showed a bias of <5%. The LOD and LOQ were 2.0 and 2.5 ng/ml for cyclosporin A, and 0.3 and 0.4 ng/ml for tacrolimus, respectively. Interference from the matrix was not observed. The CLIA measurements of cyclosporin A and tacrolimus showed correlations corresponding with the formulae: Concentration(CLIA) = 1.18 × UPLC-TMS – 5.85; [95% CI: proportional, 1.16–1.19; constant, −6.86–(−4.81)] and Concentration(CLIA) = 1.14 × UPLC-TMS – 0.38; [(95% CI: proportional, 1.13–1.14; constant, −0.35–(−0.43)], respectively. The majority of results were higher for the immunoassay than for the UPLC-TMS. The newly developed rapid UPLC-TMS method was suitable for use with a large therapeutic concentration range of the analyzed immunosuppressive drugs. Sample preparation was simple and it was possible to detect several immunosuppressants simultaneously, thus significantly lowering the cost of analysis. In conclusion, this method may contribute to improved accuracy and may be preferred to immunoassays for the routine clinical measurement of immunosuppressive drug concentrations in whole blood.
doi:10.3892/etm.2013.1325
PMCID: PMC3829750  PMID: 24255687
cyclosporin A; tacrolimus; ultra-performance liquid chromatography; tandem mass spectrometry; chemiluminescence immunoassay
6.  A validated ultra high-pressure liquid chromatography method for separation of candesartan cilexetil impurities and its degradents in drug product 
Pharmaceutical Methods  2012;3(1):31-39.
Introduction:
A selective, specific, and sensitive “Ultra High-Pressure Liquid Chromatography” (UPLC) method was developed for determination of candesartan cilexetil impurities as well asits degradent in tablet formulation.
Materials and Methods:
The chromatographic separation was performed on Waters Acquity UPLC system and BEH Shield RP18 column using gradient elution of mobile phase A and B. 0.01 M phosphate buffer adjusted pH 3.0 with Orthophosphoric acid was used as mobile phase A and 95% acetonitrile with 5% Milli Q Water was used as mobile phase B. Ultraviolet (UV) detection was performed at 254 nm and 210 nm, where (CDS-6), (CDS-5), (CDS-7), (Ethyl Candesartan), (Desethyl CCX), (N-Ethyl), (CCX-1), (1 N Ethyl Oxo CCX), (2 N Ethyl Oxo CCX), (2 N Ethyl) and any unknown impurity were monitored at 254 nm wavelength, and two process-related impurities, trityl alcohol and MTE impurity, were estimated at 210 nm. Candesartan cilexetil andimpurities were chromatographed with a total run time of 20 min.
Results:
Calibration showed that the response of impurity was a linear function of concentration over the range limit of quantification to 2 μg/mL (r2≥0.999) and the method was validated over this range for precision, intermediate precision, accuracy, linearity, and specificity. For the precision study, percentage relative standard deviation of each impurity was <15% (n=6).
Conclusion:
The method was found to be precise, accurate, linear, and specific. The proposed method was successfully employed for estimation of candesartan cilexetil impurities in pharmaceutical preparations.
doi:10.4103/2229-4708.97718
PMCID: PMC3658068  PMID: 23781475
Degradent; impurities; method validation; ultra high-pressure liquid chromatography – candesartan cilexetil
7.  Development and validation of the liquid chromatographic method for simultaneous estimation of metformin, pioglitazone, and glimepiride in pharmaceutical dosage forms 
Pharmaceutical Methods  2012;3(1):9-13.
Introduction:
A simple, precise, and accurate HPLC method for simultaneous estimation of metformin hydrochloride (MET), pioglitazone hydrochloride (PIO), and glimepiride (GLIMP) was developed and validated.
Materials and Methods:
Chromatographic separation of the drugs was performed by using a Phenomenex-ODS-3 (C-18) column (250 × 4.60 mm, 5 μm) with a mobile phase consisting of methanol:acetonitrile:15 mM potassium dihydrogen phosphate (pH 4) in the proportion of 40:35:25 (v/v) at a flow rate of 1 ml/min. Detection was carried out using a UV-SPD-10AVP detector at 240 nm.
Results:
The retention time for MET, PIO, and GLIMP were 2.85 ± 0.03 min, 4.52 ± 0.03 min, and 7.08 ± 0.02min, respectively. Parameters such as linearity (0.2–50 μg/ ml for MET, 0.2–30 μg/ml for PIO, and GLIMP, respectively), precision (intra-day % RSD was 1.01–3.24 and inter-day % RSD was 1.54–4.09 for MET; intra-day % RSD was 1.03–2.09 and inter-day % RSD was 2.26–3.10 for PIO; and intra-day% RSD was 1.00–3.15 and inter-day % RSD was 1.58–3.07 for GLIMP), accuracy (99.66 ± 0.14 for MET, 98.46 ± 0.40 for PIO, and 98.62 ± 0.39 for GLIMP), specificity and robustness were calculated in accordance with ICH guidelines.
Conclusions:
The method was proved to be simple, rapid, precise, accurate, and cost effective.
doi:10.4103/2229-4708.97707
PMCID: PMC3658067  PMID: 23781471
Glimepiride; ICH guidelines ;  metformin hydrochloride; pioglitazone hydrochloride; simultaneous
8.  A New Rapid and Sensitive Stability-Indicating UPLC Assay Method for Tolterodine Tartrate: Application in Pharmaceuticals, Human Plasma and Urine Samples 
Scientia Pharmaceutica  2011;80(1):101-114.
A new rapid, simple, sensitive, selective and accurate reversed-phase stability-indicating Ultra Performance Liquid Chromatography (RP-UPLC) technique was developed for the assay of Tolterodine Tartrate in pharmaceutical dosage form, human plasma and urine samples. The developed UPLC method is superior in technology to conventional HPLC with respect to speed, solvent consumption, resolution and cost of analysis. Chromatographic run time was 6 min in reversed-phase mode and ultraviolet detection was carried out at 220 nm for quantification. Efficient separation was achieved for all the degradants of Tolterodine Tartrate on BEH C18 sub-2-μm Acquity UPLC column using Trifluoroacetic acid and acetonitrile as organic solvent in a linear gradient program. The active pharmaceutical ingredient was extracted from tablet dosage form using a mixture of acetonitrile and water as diluent. The calibration graphs were linear and the method showed excellent recoveries for bulk and tablet dosage form. The test solution was found to be stable for 40 days when stored in the refrigerator between 2 and 8 °C. The developed UPLC method was validated and meets the requirements delineated by the International Conference on Harmonization (ICH) guidelines with respect to linearity, accuracy, precision, specificity and robustness. The intra-day and inter-day variation was found be less than 1%. The method was reproducible and selective for the estimation of Tolterodine Tartrate. Because the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one.
doi:10.3797/scipharm.1110-14
PMCID: PMC3293361  PMID: 22396907
Column liquid chromatography; Ultra Performance Liquid Chromatography; UPLC; Tolterodine Tartrate; Validation and quantification
9.  A Rapid, Stability Indicating RP-UPLC Method for Simultaneous Determination of Ambroxol Hydrochloride, Cetirizine Hydrochloride and Antimicrobial Preservatives in Liquid Pharmaceutical Formulation 
Scientia Pharmaceutica  2011;79(3):525-543.
A stability indicating reversed phase ultra performance liquid chromatography (RP-UPLC) method was developed for simultaneous determination of ambroxol hydrochloride (AMB), cetirizine hydrochloride (CTZ), methylparaben (MP) and propylparaben (PP) in liquid pharmaceutical formulation. The desired chromatographic separation was achieved on an Agilent Eclipse plus C18, 1.8 μm (50 × 2.1 mm) column using gradient elution at 237 nm detector wavelength. The optimized mobile phase consists of a mixture of 0.01 M phosphate buffer and 0.1 % triethylamine as a solvent-A and acetonitrile as a solvent-B. The developed method separates AMB, CTZ, MP and PP in presence of twelve known impurities/degradation products and one unknown degradation product within 3.5 min. Stability indicating capability was established by forced degradation experiments and seperation of known and unknown degradation products. The lower limit of quantification was established for AMB, CTZ, MP and PP. The developed RP-UPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. This validated method is applied for simultaneous estimation of AMB, CTZ, MP and PP in commercially available syrup samples. Further, the method can be extended for estimation of AMB, CTZ, MP, PP and levo-cetirizine (LCTZ) in various commercially available dosage forms.
doi:10.3797/scipharm.1103-19
PMCID: PMC3163363  PMID: 21886901
Cetirizine dihydrochloride; Methylparaben; Propylparaben; Levo-cetirizine; Bromhexine; Method validation; Forced degradation; Oral solution; Assay; Chromatography; UV spectra
10.  Development and Validation of a UPLC Method by the QbD-Approach for the Estimation of Rabeprazole and Levosulpiride from Capsules 
Scientia Pharmaceutica  2014;82(2):307-326.
Statistical experimental design was used to optimize the chromatographic separations of two pharmaceutical compounds from their respective potential impurities. A fractional factorial design was utilized to study the effects of pH, organic solvent in mobile phases A&B, and flow rate on the resolution of Rabeprazole and Rabeprazole Sulfone, which had closely eluting peaks. A desirability function applied to the optimized conditions predicted the peak resolution between 2.2 and 2.7 for the Rabeprazole & Rabeprazole Sulfone impurity. The chromatographic method employed an Acquity UPLC, BEH C18 column (100 × 2.1 mm i.d., 1.7 μm particle size) with the mobile phase consisting of a phosphate buffer, pH 6.5, and acetonitrile in a gradient program. The flow rate and injection volumes were 0.45 mL/min & 5 μl, respectively, and detection was done at 254 nm. The chromatographic method was validated for linearity, accuracy, precision, specificity, and ruggedness according to ICH guidelines. The results clearly showed that the quality by design concept could be effectively applied to optimize a UPLC chromatographic method with fewer trials and error-free experimentation.
doi:10.3797/scipharm.1310-17
PMCID: PMC4065125  PMID: 24959404
Rabeprazole sodium; Levosulpiride; UPLC; Method Validation; Experimental design
11.  Simultaneous quantitation of chloroquine and primaquine by UPLC-DAD and comparison with a HPLC-DAD method 
Malaria Journal  2015;14:29.
Background
Chloroquine and primaquine are the first-line treatment recommended by World Health Organization for malaria caused by Plasmodium vivax. Since the problem of counterfeit or substandard anti-malarials is well established all over the world, the development of rapid and reliable methods for quality control analysis of these drugs is essential. Thus, the aim of this study was to develop and validate a novel UPLC-DAD method for simultaneously quantifying chloroquine and primaquine in tablet formulations.
Methods
The UPLC separation was carried out using a Hypersil C18 column (50 × 2.1 mm id; 1.9 μm particle size) and a mobile phase composed of acetonitrile (A) and 0.1% aqueous triethylamine, pH 3.0 adjusted with phosphoric acid (B), at a flow rate 0.6 mL/min. Gradient elution was employed. UV detection was performed at 260 nm. UPLC method was fully validated and the results were compared to a conventional HPLC-DAD method for the analysis of chloroquine and primaquine in tablet formulations.
Results
UPLC method was shown to be linear (r2 > 0.99), precise (CV < 2.0%), accurate (recovery rates from 98.11 to 99.83%), specific, and robust. No significant differences were observed between the chloroquine and primaquine contents obtained by UPLC and HPLC methods. However, UPLC method promoted faster analyses, better chromatographic performance and lower solvent consumption.
Conclusions
The developed UPLC method was shown to be a rapid and suitable technique to quantify chloroquine and primaquine in pharmaceutical preparations and may be successfully employed for quality control analysis.
doi:10.1186/s12936-015-0570-1
PMCID: PMC4318193  PMID: 25626728
Chloroquine; Primaquine; Anti-malarials; UPLC-DAD; Tablets
12.  Development and validation of a repharsed phase- HPLC method for simultaneous determination of rosiglitazone and glimepiride in combined dosage forms and human plasma 
Background
Rosiglitazone (ROZ) and glimepiride (GLM) are antidiabetic agents used in the treatment of type 2 diabetes mellitus. A survey of the literature reveals that only one spectrophotometric method has been reported for the simultaneous determination of ROS and GLM in pharmaceutical preparations. However the reported method suffers from the low sensitivity, for this reason, our target was to develop a simple sensitive HPLC method for the simultaneous determination of ROZ and GLM in their combined dosage forms and plasma.
Results
A simple reversed phase high performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous determination of Rosiglitazone (ROS) and Glimepiride (GLM) in combined dosage forms and human plasma. The separation was achieved using a 150 mm × 4.6 mm i.d., 5 μm particle size Symmetry® C18 column. Mobile phase containing a mixture of acetonitrile and 0.02 M phosphate buffer of pH 5 (60: 40, V/V) was pumped at a flow rate of 1 mL/min. UV detection was performed at 235 nm using nicardipine as an internal standard. The method was validated for accuracy, precision, specificity, linearity, and sensitivity. The developed and validated method was successfully used for quantitative analysis of Avandaryl™ tablets. The chromatographic analysis time was approximately 7 min per sample with complete resolution of ROS (tR = 3.7 min.), GLM (tR = 4.66 min.), and nicardipine (tR, 6.37 min). Validation studieswas performed according to ICH Guidelines revealed that the proposed method is specific, rapid, reliable and reproducible. The calibration plots were linear over the concentration ranges 0.10-25 μg/mL and 0.125-12.5 μg/mL with LOD of 0.04 μg/mL for both compounds and limits of quantification 0.13 and 0.11 μg/mL for ROS and GLM respectively.
Conclusion
The suggested method was successfully applied for the simultaneous analysis of the studied drugs in their co-formulated tablets and human plasma. The mean percentage recoveries in Avandaryl™ tablets were 100.88 ± 1.14 and 100.31 ± 1.93 for ROS and GLM respectively. Statistical comparison of the results with those of the reference method revealed good agreement and proved that there were no significant difference in the accuracy and precision between the two methods respectively. The interference likely to be introduced from some co-administered drugs such as glibenclamide, gliclazide, metformine, pioglitazone and nateglinide was investigated.
doi:10.1186/1752-153X-6-9
PMCID: PMC3292994  PMID: 22277722
HPLC; rosiglitazone (ROS); glimepiride (GLM); human plasma
13.  Determination of Cephalexin Monohydrate in Pharmaceutical Dosage Form by Stability-Indicating RP-UFLC and UV Spectroscopic Methods 
Scientia Pharmaceutica  2013;81(4):1029-1041.
An ultra-fast liquid chromatographic method and two UV spectroscopic methods were developed for the determination of cephalexin monohydrate in pharmaceutical dosage forms. Isocratic separation was performed on an Enable C18G column (250 mm × 4.6 mm i.d., 5 μm) using methanol:0.01 M TBAHS (50:50, v/v) as the mobile phase at a flow rate of 1.0 ml/min. The PDA detection wavelength was set at 254 nm. The UV spectroscopic method was performed at 261 nm and at 256–266 nm for the AUC method using a phosphate buffer (pH=5.5). The linearity was observed over a concentration range of 1.0–120 μg/ml for UFLC and both of the UV spectroscopic methods (correlation coefficient=0.999). The developed methods were validated according to ICH guidelines. The relative standard deviation values for the intraday and interday precision studies were < 2%, and the accuracy was > 99% for all of the three methods. The developed methods were used successfully for the determination of cephalexin in dry syrup formulation.
doi:10.3797/scipharm.1306-07
PMCID: PMC3867238  PMID: 24482771
AUC; Cefalexin; Spectroscopy; UFLC-PDA; Chromatography
14.  Simultaneous Determination of Sitagliptin and Metformin in Pharmaceutical Preparations by Capillary Zone Electrophoresis and its Application to Human Plasma Analysis 
A novel, quick, reliable and simple capillary zone electrophoresis CZE method was developed and validated for the simultaneous determination of sitagliptin (SG) and metformin (MF) in pharmaceutical preparations. Separation was carried out in fused silica capillary (50.0 cm total length and 43.0 cm effective length, 49 μm i.d.) by applying a potential of 15 KV (positive polarity) and a running buffer containing 60 mM phosphate buffer at pH 4.0 with UV detection at 203 nm. The samples were injected hydrodynamically for 3 s at 0.5 psi and the temperature of the capillary cartridge was kept at 25 °C. Phenformin was used as internal standard (IS). The method was suitably validated with respect to specificity, linearity, limit of detection and quantitation, accuracy, precision, and robustness. The method showed good linearity in the ranges of 10–100 μg/mL and 50–500 μg/mL with limits of detection of 0.49, 2.11 μg/mL and limits of quantification of 1.48, 6.39 μg/mL for SG and MF, respectively. The proposed method was successfully applied for the analysis of the studied drugs in their synthetic mixtures and co-formulated tablets without interfering peaks due to the excipients present in the pharmaceutical tablets. The method was further extended to the in-vitro determination of the two drugs in spiked human plasma. The estimated amounts of SG/MF were almost identical with the certified values, and their percentage relative standard deviation values (% R.S.D.) were found to be ≤1.50% (n = 3). The results were compared to a reference method reported in the literature and no significant difference was found statistically.
doi:10.4137/ACI.S9940
PMCID: PMC3418147  PMID: 22904611
sitagliptin; metformin; simultaneous determination; capillary zone electrophoresis; validation; pharmaceutical preparations; human plasma
15.  Identification and Characterization of an Oxidative Degradation Product of Fexofenadine, Development and Validation of a Stability-Indicating RP-UPLC Method for the Estimation of Process Related Impurities and Degradation Products of Fexofenadine in Pharmaceutical Formulations 
Scientia Pharmaceutica  2012;80(2):295-309.
A novel stability-indicating gradient RP-UPLC method was developed for the quantitative determination of process related impurities and forced degradation products of fexofenadine HCl in pharmaceutical formulations. The method was developed by using Waters Aquity BEH C18 (100 mm x 2.1 mm) 1.7 μm column with mobile phase containing a gradient mixture of solvent A (0.05% triethyl amine, pH adjusted to 7.0 with ortho-phosphoric acid) and B (10:90 v/v mixture of water and acetonitrile). The flow rate of mobile phase was 0.4 mL/min with column temperature of 30°C and detection wavelength at 220nm. Fexofenadine HCl was subjected to the stress conditions including oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Fexofenadine HCl was found to degrade significantly in oxidative stress conditions, and degradation product was identified and characterized by ESI-MS/MS, 1H and 13C NMR spectroscopic method as the N-oxide 2-[4-(1-hydroxy-4-{4-[hydroxy(diphenyl)methyl]-1-oxido-piperidin-1-yl}butyl)phenyl]-2-methylpropanoic acid. The degradation products were well resolved from fexofenadine and its impurities. The mass balance was found to be satisfactory in all the stress conditions, thus proving the stability-indicating capability 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.
doi:10.3797/scipharm.1111-07
PMCID: PMC3383222  PMID: 22896817
Fexofenadine; Validation; Stability-indicating; Forced degradation; Identification; characterization; UPLC
16.  Spectroflourometric and Spectrophotometric Methods for the Determination of Sitagliptin in Binary Mixture with Metformin and Ternary Mixture with Metformin and Sitagliptin Alkaline Degradation Product 
Simple, accurate and precise spectroflourometric and spectrophotometric methods have been developed and validated for the determination of sitagliptin phosphate monohydrate (STG) and metformin HCL (MET). Zero order, first derivative, ratio derivative spectrophotometric methods and flourometric methods have been developed. The zero order spectrophotometric method was used for the determination of STG in the range of 50-300 μg mL-1. The first derivative spectrophotometric method was used for the determination of MET in the range of 2–12 μg mL-1 and STG in the range of 50-300 μg mL-1 by measuring the peak amplitude at 246.5 nm and 275 nm, respectively. The first derivative of ratio spectra spectrophotometric method used the peak amplitudes at 232 nm and 239 nm for the determination of MET in the range of 2–12 μg mL-1. The flourometric method was used for the determination of STG in the range of 0.25-110 μg mL-1. The proposed methods used to determine each drug in binary mixture with metformin and ternary mixture with metformin and sitagliptin alkaline degradation product that is obtained after alkaline hydrolysis of sitagliptin. The results were statistically compared using one-way analysis of variance (ANOVA). The methods developed were satisfactorily applied to the analysis of the pharmaceutical formulations and proved to be specific and accurate for the quality control of the cited drugs in pharmaceutical dosage forms.
PMCID: PMC3614813  PMID: 23675222
metformin; sitagliptin phosphate; spectrophotometry; stability indicating assay; flourometry; pharmaceutical preparation
17.  Validation of a Thin-Layer Chromatography for the Determination of Hydrocortisone Acetate and Lidocaine in a Pharmaceutical Preparation 
The Scientific World Journal  2014;2014:107879.
A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform + acetone + ammonia (25%) in volume composition 8 : 2 : 0.1 and silica gel 60F254 plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of 3.75 ÷ 12.50 μg·spot−1, and from 1.00 ÷ 2.50 μg·spot−1 for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198 μg·spot−1 and LOD is 0.066 μg·spot−1. LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090 μg·spot−1, respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia.
doi:10.1155/2014/107879
PMCID: PMC3913387  PMID: 24526880
18.  Simultaneous Estimation of Metformin Hydrochloride and Pioglitazone Hydrochloride by RPHPLC Method from Combined Tablet Dosage Form 
A high performance reverse phase liquid chromatographic procedure is developed for simultaneous estimation of metformin hydrochloride and pioglitazone hydrochloride in combined tablet dosage form. The mobile phase used was a combination of acetonitrile:water:acetic acid (60:40:0.3) and the pH was adjusted to 5.5 by adding triethylamine. The detection of the combined dosage form was carried out at 230 nm and a flow rate employed was 1 ml/min. Linearity was obtained in the concentration range of 0.015 to 0.120 μg/ml of pioglitazone hydrochloride and 0.5 to 4.0 μg/ml of metformin hydrochloride with a correlation coefficient of 0.9992 and 0.9975. The results of the analysis were validated statistically and recovery studies confirmed the accuracy and precision of the proposed method.
doi:10.4103/0250-474X.43010
PMCID: PMC2792515  PMID: 20046754
Pioglitazone hydrochloride; metformin hydrochloride; reverse-phase; simultaneous estimation
19.  HPLC Method for Estimation of Metformin Hydrochloride in Formulated Microspheres and Tablet Dosage Form 
A simple, accurate, economical and reproducible HPLC method has been developed for quantitative estimation of metformin hydrochloride from tablet dosage form and formulated microspheres. The developed HPLC method is a reverse phase chromatographic method using phenomenex C18 column and acetonitrile:phosphate buffer (65:35) pH adjusted to 5.75 with o-phosphoric acid as mobile phase and glipizide as internal standard. The linearity was observed in concentration range of 0-25 μg/ml for metformin hydrochloride. Results of analysis were validated statistically and by recovery studies.
doi:10.4103/0250-474X.56031
PMCID: PMC2865795  PMID: 20490303
HPLC; metformin hydrochloride; microspheres; recovery studies; tablet
20.  Development and validation of an high-performance liquid chromatographic, and a ultraviolet spectrophotometric method for determination of Ambroxol hydrochloride in pharmaceutical preparations 
A high-performance liquid chromatographic (HPLC) and ultraviolet (UV) methods were developed and validated for the quantitative determination of Ambroxol hydrochloride (AMH) in pharmaceutical dosage form. HPLC was carried out by reversed phase (RP) technique on an RP-18 column with a mobile phase composed of acetonitrile and water (pH 3.5 adjusted with orthophosphoric acid [60:40, v/v]). UV method was performed with the λmax at 250 nm. Both the methods showed good linearity, reproducibility, and precision. No spectral or chromatographic interferences from the tablet excipients were found in UV and HPLC. The method was successfully applied to commercial tablets. Validation parameters such as linearity, precision, accuracy, and specificity were determined. The HPLC Limit of detection (LOD) and Limit of quantification (LOQ) for Ambroxol were found to be 1 and 5 ng/ml, respectively. The UV LOD and LOQ for Ambroxol were found to be 1 and 4 μg/ml, respectively. The results were statistically compared using one-way analysis of variance. The proposed economical method could be applicable for routine analysis of AMH and monitoring of the quality of marketed drugs.
doi:10.4103/2231-4040.107503
PMCID: PMC3645355  PMID: 23662284
Ambroxol hydrochloride; high-performance liquid chromatographic; tablets; ultraviolet
21.  Stability Indicating RP-HPLC Estimation of Nebivolol Hydrochloride in Pharmaceutical Formulations 
A simple, specific, accurate and stability indicating reversed phase liquid chromatographic method was developed for the determination of nebivolol hydrochloride in tablet dosage forms. A phenomenex Gemini C-18, 5 μm column having 250×4.6 mm i.d., with mobile phase containing methanol: acetonitrile: 0.02 M potassium dihydrogen phosphate (60:30:10, v/v/v; pH 4.0) was used. The retention time of nebivolol hydrochloride was 2.6 min. The linearity for nebivolol hydrochloride was in the range of 0.2-10 μg/ml. The recovery was found to be in the range of 98.68-100.86%. The detection limit and quantification limit were found to be 0.06 μg/ml and 0.2 μg/ml, respectively. Nebivolol stock solutions were subjected to acid, alkali and neutral hydrolysis, chemical oxidation and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their retention time values. The proposed method was validated and successfully applied to the estimation of nebivolol hydrochloride in tablet formulations.
doi:10.4103/0250-474X.45396
PMCID: PMC3038282  PMID: 21394254
Nebivolol hydrochloride (NEB); degradation; reversed phase liquid chromatography; stability indicating; validation
22.  Development and validation of a UPLC method for the determination of duloxetine hydrochloride residues on pharmaceutical manufacturing equipment surfaces 
Pharmaceutical Methods  2011;2(3):161-166.
Background:
In pharmaceutical industries, it is very important to remove drug residues from the equipment and areas used. The cleaning procedure must be validated, so special attention must be devoted to the methods used for analysis of trace amounts of drugs. A rapid, sensitive, and specific reverse phase ultra-performance liquid chromatographic (UPLC) method was developed for the quantitative determination of duloxetine in cleaning validation swab samples.
Material and Methods:
The method was validated using an Acquity UPLC™ HSS T3 (100 × 2.1 mm2) 1.8 μm column with a isocratic mobile phase containing a mixture of 0.01 M potassium dihydrogen orthophosphate, pH adjusted to 3.0 with orthophosphoric acid and acetonitrile (60:40 v/v). The flow rate of the mobile phase was 0.4 ml/min with a column temperature of 40°C and detection wavelength at 230 nm. Cotton swabs, moisten with extraction solution (90% methanol and 10% water), were used to remove any residue of drug from stainless steel, glass and silica surfaces, and give recoveries >80% at four concentration levels.
Results:
The precision of the results, reported as the relative standard deviation, were below 1.5%. The calibration curve was linear over a concentration range from 0.02 to 5.0 μg/ml with a correlation coefficient of 0.999. The detection limit and quantitation limit were 0.006 and 0.02 μg/ml, respectively. The method was validated over a concentration range of 0.05–5.0 μg/ml.
Conclusion:
The developed method was validated with respect to specificity, linearity, limit of detection and quantification, accuracy, precision, and robustness.
doi:10.4103/2229-4708.90355
PMCID: PMC3658054  PMID: 23781449
Cleaning validation; duloxetine; residues; swab analysis; UPLC-UV
23.  Quantitative Thin-Layer Chromatographic Method for Determination of Amantadine Hydrochloride 
A simple and accurate thin-layer chromatographic (TLC) method for quantitative determination of amantadine hydrochloride (AMD) was developed and validated. The method employed TLC aluminum plates pre-coated with silica gel 60F-254 as a stationary phase. The solvent system used for development consisted of n-hexane-methanol-diethylamine (80: 40: 5, v/v/v). The separated spots were visualized as brown spots after spraying with modified Dragendorff’s reagent solution. Amantadine hydrochloride was subjected to accelerated stress conditions: boiling, acid and alkaline hydrolysis, oxidation, and irradiation with ultraviolet light. The drug was found to be stable under all the investigated stress conditions. The method was validated for linearity, limits of detection (LOD) and quantitation (LOQ), precision, robustness, selectivity and accuracy. The optical densities of the separated spots were found to be linear with the amount of AMD in the range of 5-40 µg/spot with good correlation coefficient (r=0.9994). The LOD and LOQ values were 0.72 and 2.38 µg/spot, respectively. Statistical analysis proved that the method is repeatable and accurate for the determination of AMD. The method, in terms of its sensitivity, accuracy, precision, and robustness met the International Conference of Harmonization/Federal Drug Administration regulatory requirements. The proposed TLC method was successfully applied for the determination of AMD in bulk and capsules with good accuracy and precision; the label claim percentages were 99.0 ± 1.0%. The results obtained by the proposed TLC method were comparable with those obtained by the official method. The proposed method is more advantageous than the previously published chromatographic methods as it involved the most simple chromatographic technique; TLC. In addition, method relies on the use of inexpensive equipment, a scanner and software, and not critical derivatizing reagent, thus maximizing the ability of laboratories worldwide to analyze samples of AMD.
PMCID: PMC3614699  PMID: 23675083
amantadine hydrochloride; thin-layer chromatography; stability-indicating; pharmaceutical analysis
24.  A UPLC–MS Method for the Determination of Ofloxacin Concentrations in Aqueous Humor 
A rapid, simple, and specific method based on ultra performance liquid chromatography (UPLC) with mass spectrometry detection has been developed for quantitative analysis of ofloxacin in human aqueous humor using tobramycin as internal standard (IS). Chromatographic separation was achieved on a Waters Acquity UPLC BEH C18 Shield column (150 × 2.1 mm, 1.7 μm) eluted with 95:5 water: acetonitrile (v/v) containing 0.1% formic acid and a flow rate of 0.3 mL/minute. The total analysis time was three minutes with ofloxacin eluting at 1.67 ± 0.03 minutes. The linearity of the method ranged from 0.1 to 8 μg/mL with r2 = 0.998. The method was validated according to FDA guidelines with respect to linearity, accuracy, precision, specificity, and stability. The limits of detection and quantification were 0.03 and 0.10 μg/mL, respectively. The developed method was successfully applied to the analysis of samples that have been obtained from patients.
doi:10.4137/ACI.S13857
PMCID: PMC4022703  PMID: 24868142
UPLC; ofloxacin; mass spectrometry; aqueous humor
25.  Development and Validation of a HPLC Method to Determine Griseofulvin in Rat Plasma: Application to Pharmacokinetic Studies 
A simple, specific, sensitive, and rapid high performance liquid chromatography (HPLC) method for the determination of griseofulvin in small volumes of rat plasma was developed and validated using warfarin as an internal standard. Biological sample preparation involved simple extraction with acetonitrile, followed by dilution with aqueous mobile phase buffer (20 mM sodium dihydrogen phosphate, pH 3.5) to eliminate any chromatographic solvent effects. Griseofulvin and warfarin were baseline separated and quantitated on a C18 reversed phase column (4.6 × 150 mm, 3.5 μm), using a mobile phase composed of a 20 mM aqueous solution of sodium dihydrogen phosphate-acetonitrile (55:45, v/v, pH 3.5) delivered at a flow rate of 1.0 mL/min, and with fluorescence detection (λexcitation = 300 nm, λemission = 418 nm). The method was proven to be linear over a plasma griseofulvin concentration range of 10 to 2500 ng/mL with a mean correlation coefficient of 0.9996. The intra-day and inter-day accuracy (relative error) were in the range of 0.89% to 9.26% and 0.71% to 7.68%, respectively. The within-day precision (coefficient of variation) was less than 3.0% and the between-day precision was less than 7.5%. The mean recovery of griseofulvin from rat plasma was found to be 99.2%. The limit of detection (LOD) and the limit of quantification (LOQ) of griseofulvin were determined to be 1 ng/mL and 10 ng/mL, respectively. The developed method was successfully applied to quantitatively assess the pharmacokinetics of griseofulvin in rats following a single 50 mg/kg oral dose of the drug.
PMCID: PMC2701169  PMID: 19609394
griseofulvin; HPLC; fluorescence; pharmacokinetics; rat plasma

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