A stability-indicating LC method for the simultaneous determination of ramipril and hydrochlorothiazide in dosage forms

A simple, rapid and sensitive HPLC method has been developed for the simultaneous determination of ramipril and hydrochlorothiazide in their dosage forms. Acetonitrile: sodium perchlorate solution (0.1 M) adjusted to pH 2.5+/-0.2 with phosphoric acid (46:54 v/v), was used as the mobile phase, at a flow rate of 1.5 ml/min. A supelcosil LC-8 column (5 microm), 15 cm x 4.6 mm i.d. was utilized as stationary phase. Detection was affected spectrophotometrically at 210 nm. Clobazam was used as an internal standard. The method was also applied for the determination of ramipril in the presence of its degradation products. Linearity ranges for ramipril and hydrochlorothiazide were 4.5-45 and 0.6-14 microg/ml, respectively. Minimum detection limits (S/N = 2) obtained were 180 and 23 ng/ml for ramipril and hydrochlorothiazide, respectively. The proposed method was further applied to the analysis of tablets containing the two drugs, the percentage recoveries +/- S.D. (n = 5) were 100.45%+/-0.63 and 99.55%+/-0.78 for ramipril and hydrochlorothiazide, respectively.     

Simultaneous determination of valsartan and hydrochlorothiazide in tablets by first-derivative ultraviolet spectrophotometry and LC

First-derivative ultraviolet spectrophotometry and high-performance liquid chromatography (HPLC) were used to determine valsartan and hydrochlorothiazide simultaneously in combined pharmaceutical dosage forms. The derivative procedure was based on the linear relationship between the drug concentration and the first derivative amplitudes at 270.6 and 335 nm for valsartan and hydrochlorothiazide, respectively. The calibration graphs were linear in the range of 12.0–36.1 μg ml⁻¹ for valsartan and 4.0–12.1 μg ml⁻¹ for hydrochlorothiazide. Furthermore, a high- performance liquid chromatographic procedure with ultraviolet detection at 225 nm was developed for a comparison method. For the HPLC procedure, a reversed phase column with a mobile phase of 0.02 M phosphate buffer (pH 3.2)-acetonitrile (55: 45; v/v), was used to separate for valsartan and hydrochlorothiazide. The plot of peak area ratio of each drug to the internal standard versus the respective concentrations of valsartan and hydrochlorothiazide were found to be linear in the range of 0.06–1.8 and 0.07–0.5 μg ml⁻¹, respectively. The proposed methods were successfully applied to the determination of these drugs in laboratory-prepared mixtures and commercial tablets.     

Spectrophotometric and HPLC Methods for Simultaneous Estimation of Amlodipine Besilate, Losartan Potassium and Hydrochlorothiazide in Tablets

Two UV-spectrophotometric and one reverse phase high performance liquid chromatography methods have been developed for the simultaneous estimation of amlodipine besilate, losartan potassium and hydrochlorothiazide in tablet dosage form. The first UV spectrophotometric method was a determination using the simultaneous equation method at 236.5, 254 and 271 nm over the concentration range 5-25, 10-50 and 5-25 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. The second UV method was a determination using the area under curve method at 231.5-241.5, 249-259 and 266-276 nm over the concentration range of 5-25, 5-25 and 10-50 μg/ml for amlodipine besilate, hydrochlorothiazide and losartan potassium, respectively. In reverse phase high performance liquid chromatography analysis is carried out using 0.025 M phosphate buffer (pH 3.7):acetonitrile (57:43 v/v) as the mobile phase and Kromasil C18 (4.6 mm i.d×250 mm) column as stationery phase with detection wavelength of 232 nm linearity was obtained in the concentration range of 2-14, 20-140 and 5-40 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. Both UV-spectrophotometric and reverse phase high performance liquid chromatography methods were statistically validated and can be used for analysis of combined dose tablet formulation containing amlodipine besilate, losartan potassium and hydrochlorothiazide.     

RP-HPLC Method for Simultaneous Estimation of Nitazoxanide and Ofloxacin in Tablets

A reverse phase high performance liquid chromatography method was developed for simultaneous estimation of nitazoxanide and ofloxacin in tablet formulation. The separation and quantification was achieved by Hiq Sil C₁₈V Size 4.6 mm Ø ^*250 mm column in isocratic mode, with mobile phase consisting of acetonitrile-methanol-0.4 M citric acid, (60:30:10, v/v/v). Citric acid used to stabilize nitazoxanide and ofloxacin in mobile phase. The mobile phase was pumped at a rate of 0.6 ml/min and the detection was carried out at 304 nm. The retention time of ofloxacin and nitazoxanide was found to be 3.122 and 5.902 min, respectively. The method was validated for linearity, accuracy, and precision. Linearity for ofloxacin and nitazoxanide were in the range 2-36 μg/ml and 5-90 μg/ml, respectively. The developed method was found to be accurate, precise and selective for simultaneous estimation of ofloxacin and nitazoxanide in tablets.     

Estimation of Amlodipine Besylate, Valsartan and Hydrochlorothiazide in Bulk Mixture and Tablet by UV Spectrophotometry

A simple, precise, accurate and economic simultaneous UV spectrophotometric method has been developed for the estimation of amlodipine besylate, valsartan and hydrochlorothiazide in combination in bulk mixture and tablet. The estimation was based upon measurement of absorbance at absorbance maxima of 359 nm, 317 nm and 250 nm for amlodipine besylate, hydrochlorothiazide and valsartan in methanol, respectively in bulk mixture and tablet. The Beer Lambert''s law obeyed in the concentration range 5-25 μg/ml, 10-50 μg/ml and 5-25 μg/ml for amlodipine besylate, hydrochlorothiazide and valsartan, respectively. The estimation of bulk mixture and tablet was carried out by simultaneous equation, Q-analysis and area under curve method for estimation of amlodipine besylate and hydrochlorothiazide and standard curve method for estimation of valsartan. The results were found to be in the range of 99.6±1.52% to 102±0.51%. Method was validated with respect to specificity, linearity, range, accuracy, precision, LOD, LOQ, robustness, ruggedness and can be applied for routine analysis of tablet dosage forms.     

Simultaneous determination of benazepril hydrochloride and hydrochlorothiazide by micro-bore liquid chromatography

A micro-bore liquid chromatographic method was developed for the simultaneous determination of benazepril hydrochloride and hydrochlorothiazide in pharmaceutical dosage forms. The use of a BDS C-18 micro-bore analytical column, results in substantial reduction in solvent consumption and increased sensitivity. The mobile phase consisted of a mixture of 0.025 M sodium dihydrogen phosphate (pH 4.8) and acetonitrile (55:45, v/v), pumped at a flow rate of 0.40 ml min(-1). Detection was set at 250 nm using an ultraviolet detector. Calibration graphs are linear (r better than 0.9991, n = 5), in concentration range 5.0-20.0 microg ml(-1) for benazepril hydrochloride and 6.2-25.0 microg ml(-1) for hydrochlorothiazide. The intra- and interday R.S.D. values were <1.25% (n = 5), while the relative percentage error (Er) was <0.9% (n = 5). The detection limits attained according to IUPAC definition were 0.88 and 0.58 microg ml(-1) for benazepril hydrochloride and hydrochlorothiazide, respectively. The method was applied in the quality control of commercial tablets and content uniformity test and proved to be suitable for rapid and reliable quality control.     

Development and Validation of a Simultaneous HPLC Method for Estimation of Bisoprolol Fumarate and Amlodipine Besylate from Tablets

A fast, robust and stability indicating RP-HPLC method was developed for simultaneous determination of bisoprolol fumarate and amlodipine besylate in tablets. The mobile phase was mixture of 25 mM ammonium acetate adjusted to pH 5.0 and methanol (65: 35) at 0.8 ml/min. The stationary phase was Luna C18-2 column (3 μ, 50×4.6 mm ID). UV detection was performed at 230 nm. Retention time was 1.45 min and 3.91 min for bisoprolol and amlodipine, respectively. Linearity was established in the range of 8–33 μg/ml. Mean recovery was 99.1% and 98.6% for bisoprolol fumarate and amlodipine besylate, respectively.     

Simultaneous determination of cinnarizine and domepiridone maleate from tablet dosage form by reverse phase ion pair high performance liquid chromatography

A new simple, precise, rapid and selective reverse phase ion pair high performance liquid chromatography (HPLC-RP) method has been developed for the simultaneous determination of cinnarizine (CINN) and domepiridone maleate (DOME) from tablets using acetonitrile–methanol–water–0.1 N sulfuric acid (37:10:48:5 v/v/v/v) containing sodium lauryl sulfate (0.01 M), as a mobile phase and a Machery Nagel nitrile column (10 μ, 25 cm×4.0 mm i.d.) as the stationary phase. The flow of mobile phase through the column was kept at 1.0 ml min⁻¹ through out the analysis. Detection was carried out using a UV detector at 225 nm. The retention times for CINN and DOME were 4.73 and 9.41 min, respectively. The linearity range and percentage recoveries for CINN and DOME were 4–1000 and 60–750 μg ml⁻¹ and 99.90 and 99.60%, respectively.     

Simultaneous Estimation of Nebivolol Hydrochloride and Valsartan using RP HPLC

In this study, a rapid, precise, accurate, specific and sensitive ion-paired reverse phase liquid chromatographic method has been developed for the simultaneous estimation of nebivolol hydrochloride and valsartan in their capsule formulation. The chromatographic method was standardized using a HIQ sil C₁₈ column (250×4.6 mm i.d., 5 μm particle size) with UV detection at 289 nm and flow rate of 1 ml/min. The mobile phase consisting of methanol:water (80:20 v/v) with addition of 0.1 percent 1-hexanesulfonic acid monohydrate sodium salt as an ion-pairing reagent was selected. The method was validated and produced accurate and precise results for estimation of the two drugs.     

Application of LC and HPTLC-densitometry for the simultaneous determination of benazepril hydrochloride and hydrochlorothiazide

Two methods are described for the simultaneous determination of benazepril HCl and hydrochlorothiazide in binary mixture. The first method was based on HPTLC separation of the two drugs followed by densitometric measurements of their spots at 238 and 275 nm for benazepril HCl and hydrochlorothiazide, respectively. The separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F(254,) using ethyl acetate-methanol-chloroform (10:3:2 v/v) as mobile phase. Second order polynomial equation was used for the regression line in the range 2-20 and 2.5-25 microg/spot for benazepril HCl and hydrochlorothiazide, respectively. The second method was based on HPLC separation of the two drugs on reversed phase, ODS column at ambient temperature using a mobile phase consisting of acetonitrile and water (35:65 v/v) and adjusting to pH 3.3 with acetic acid. Quantitation was achieved with UV detection at 240 nm based on peak area with linear calibration curves at concentration ranges 10-60 and 12.5-75 microg ml(-1) for benazepril HCl and hydrochlorothiazide, respectively. The two proposed methods were successfully applied to the determination of both drugs in laboratory prepared mixtures and in commercial tablets. No chromatographic interference from the tablets excipients was found.     

RP-HPLC Method for the Determination of Losartan Potassium and Ramipril in Combined Dosage Form

A simple, specific and accurate reverse phase liquid chromatographic method was developed for the simultaneous determination of losartan potassium and ramipril in table dosage forms. A hypersil ODS C18, 4.6×250 mm, 5 μm column in isocratic mode, with mobile phase acetonitrile:methanol:10 mM tetra butyl ammonium hydrogen sulphate in water in the ratio of 30:30:40% v/v/v was used. The flow rate was 1.0 ml/min and effluent was monitored at 210 nm. The retention times of losartan potassium and ramipril were 4.7 and 3.3 min, respectively. The linearity range for losartan potassium and ramipril were in the range of 0.04-100 μg/ml and 0.2-300 μg/ml, respectively. The proposed method was also validated and successfully applied to the estimation of losartan potassium and ramipril in combined tablet formulations.     

Development and Validation of RP-HPLC Method for Simultaneous Estimation of Atorvastatin Calcium and Fenofibrate in Tablet Dosage Forms

A reverse phase high performance liquid chromatographic method was developed for the simultaneous estimation of atorvastatin calcium and fenofibrate in tablet formulation. The separation was achieved by Luna C18 column and methanol:acetate buffer pH 3.7 (82:18 v/v) as mobile phase, at a flow rate of 1.5 ml/min. Detection was carried out at 248 nm. Retention time of atorvastatin calcium and fenofibrate was found to be 3.02+0.1 and 9.05+0.2 min, respectively. The method has been validated for linearity, accuracy and precision. Linearity for atorvastatin calcium and Fenofibrate were in the range of 1-5 μg/ml and 16-80 μg/ml, respectively. The mean recoveries obtained for Atorvastatin calcium and fenofibrate were 101.76% and 100.06%, respectively. Developed method was found to be accurate, precise, selective and rapid for simultaneous estimation of atorvastatin calcium and fenofibrate in tablets.     

RP-HPLC Method for the Estimation of Dutasteride in Tablet Dosage Form

A simple, sensitive and precise RP-HPLC method was developed for the determination of dutasteride in tablet dosage form. The RP-HPLC separation was achieved on phenomenex C₁₈ column (250 mm, id 4.6 mm, 5 μm) using mobile phase methanol:water (90:10 v/v) at a flow rate of 1 ml/min at an ambient temperature. Quantification was achieved with photodiode array detection at 235 nm over the concentration range 1-12 μg/ml. The method was validated statistically and was applied successfully for the determination of dutasteride in tablets.     

Determination and validation of ketoprofen, pantoprazole and valsartan together in human plasma by high performance liquid chromatography

A rapid and specific high-performance liquid chromatographic method was developed and validated for the simultaneous determination of ketoprofen, valsartan and pantoprazole in human plasma. Chromatographic separation of ketoprofen, valsartan and pantoprazole was performed using a Chromasil C18 column (250 mm x 4.6 mm i.d., 5 microm particle size). The mobile phase consisted of a mixture of 0.02 M sodium dihydrogen phosphate buffer (pH 3.15) and acetonitrile (58:42, v/v) pumped through the chromatographic system at a flow rate of 1 mL x min(-1). The Diode Array detector was operated at 225 and 272 nm. Rofecoxib was used as an internal standard. Sample treatment procedure consisted of deproteinisation with acetonitrile-methanol (50:50 v/v). Analytical recoveries were in the range of 79.00-118.00% of nominal values of valsartan, ketoprofen and pantoprazole. The method was reproducible and accurate with lower limits of quantification 250 microg x L(-1) for pantoprazole and 500 microg x L(-1) for ketoprofen and valsartan. This method was relatively easy to perform and allows simultaneous determination of these three drugs in plasma at nanogram levels.     

HPTLC Method for the Simultaneous Estimation of Valsartan and Hydrochlorothiazide in Tablet Dosage Form

A simple, precise, accurate and rapid high performance thin layer chromatographic method has been developed and validated for the simultaneous estimation of valsartan and hydrochlorothiazide in combined dosage forms. The stationary phase used was precoated silica gel 60F₂₅₄. The mobile phase used was a mixture of chloroform: methanol: toluene: glacial acetic acid (6:2:1:0.1 v/v/v/v). The detection of spots were carried out at 260 nm. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found to be linear between 300 to 800 ng/spot for valsartan and 100 to 600 ng/spot for hydrochlorothiazide. The limit of detection and the limit of quantification for the valsartan were found to be 100 and 300 ng/spot respectively and for hydrochlorothiazide 30 and 100 ng/spot respectively. The proposed method can be successfully used to determine the drug content of marketed formulation.     

Stability-indicating Reversed-phase Liquid Chromatographic Method for Simultaneous Determination of Losartan Potassium and Ramipril in Tablets

A stability-indicating reversed-phase liquid chromatographic method has been developed and validated for simultaneous determination of losartan potassium and ramipril. Separations were achieved using a C₁₈ column with mobile phase consisting of acetonitrile and (0.2% v/v, pH 2.5) aqueous trifluoroacetic acid (45:55, v/v) in isocratic mode at 1 ml/min flow rate. Column effluent was monitored at 210 nm using a UV detector. The method was validated for selectivity, linearity, accuracy, precision, sensitivity and robustness. Novel microwave-assisted forced degradation technique was employed for evaluation of selectivity. The method demonstrated excellent linearity for losartan potassium and ramipril with regression coefficients of 0.9999 and 0.9998, respectively. The linearity range was found to be 62.5-5000 ng/ml and 125-10,000 ng/ml with the mean percentage recoveries of 100.36% (±2.27) and 100.16% (±3.33) for losartan potassium and ramipril, respectively. In a robustness study, a full factorial design revealed that the analytical response remains unaffected by small variations in the critical chromatographic factors. The method was found to be sensitive with quantification limits of 44.30 and 79.93 ng/ml for losartan potassium and ramipril. The method was successfully employed for the determination of losartan potassium and ramipril in commercially available and in-house prepared tablets.     

A simple and rapid high-performance liquid chromatographic method for the determination of bisoprolol fumarate and hydrochlorothiazide in a tablet dosage form

A simple and precise high performance liquid chromatographic method has been developed and validated for the simultaneous determination of bisoprolol fumarate (BF), and hydrochlorothiazide (HCTZ) in a tablet formulation. Chromatography was carried out at 25 degrees C on a 4.6 mm x 250 mm, 5 microm cyano column with the isocratic mobile phase of 0.1M aqueous phosphate buffer, acetonitrile and tetrahydrofuran (85:10:5, v/v/v) at a flow rate of 1.0 ml/min. The UV detection was carried out at 225 nm. HCTZ and BF were separated in less than 10 min with good resolution and minimal tailing, without interference of excipients. The method was validated according to ICH guidelines and the acceptance criteria for accuracy, precision, linearity, specificity and system suitability were met in all cases. The method was linear in the range of 50-150 microg/ml for BF and 125-375 microg/ml for HCTZ.     

Simultaneous Determination of Salbutamol Sulphate and Bromhexine Hydrochloride in Tablets by Reverse Phase Liquid Chromatography

A simple reverse phase liquid chromatographic method has been developed and subsequently validated for simultaneous determination of salbutamol sulphate and bromhexine hydrochloride. The separation was carried out using a mobile phase consisting of acetonitrile, methanol and phosphate buffer, pH 4 in the ratio 60:20:20 v/v. The column used was SS Wakosil-II C-18 with a flow rate of 1 ml/min and UV detection at 224 nm. The described method was linear over a concentration range of 10-110 μg/ml and 20-140 μg/ml for the assay of salbutamol sulphate and bromhexine hydrochloride, respectively. The mean recovery was found to be 95-105% for salbutamol sulphate and 96.2-102.1% for bromhexine hydrochloride when determined at five different levels.     

Determination of cetylpyridinium chloride and tetracaine hydrochloride in buccal tablets by RP-HPLC

The HPLC method for simultaneous determination of cetylpyridinium chloride (CPC), tetracaine hydrochloride (TTC) in Xipiluan buccal tablets was developed and validated. The HPLC method was performed on a CN column (150 x 4.6 mm i.d., 5 microm particle size); the mobile phase was methanol-tetramethylammonium hydroxide (20 mM)-potassium dihydrogen phosphate (3 mM) (90:10:3, v/v/v) (pH* 5.0), pumped at a flow rate 1.5 ml min(-1). The UV detector was set at 230 nm. The retention time for CPC and TTC was 3.52 and 3.10 min, respectively. Calibration curves were linear (r=0.9999, n=6) in the range of 5-2000 microg ml(-1) for CPC and 1-500 microg ml(-1) for TTC. Limit of detection and quantitation for CPC was 0.033 and 0.11 microg ml(-1), for TTC were 0.0056 and 0.019 microg ml(-1). The R.S.D. of repeatability and intermediate precision for CPC and TTC were less than 2.0%.     

RP-HPLC Method for Simultaneous Estimation of Frusemide and Amiloride Hydrochloride in Tablet Formulation

A new reverse phase high performance liquid chromatography method for the simultaneous estimation of frusemide and amiloride hydrochloride in tablet formulation is developed. The determination was carried out on a HIQ SIL, C18 (250×4.6 mm, 5 μm) column using a mobile phase of 50 mM phosphate buffer solution:acetonitrile (50:50 v/v, pH 3.0). The flow rate was 1.0 ml/min with detection at 283 nm. The retention time for frusemide was 3.038 min and for amiloride hydrochloride 10.002 min. Frusemide and amiloride hydrochloride showed a linear response in the concentration range of 20-200 μg/ml and 10-100 μg/ml, respectively. The results of analysis have been validated statistically and by recovery studies. The mean recoveries found for frusemide was 99.98% and for amiloride hydrochloride was 100.09%. Developed method was found to be simple, accurate, precise and selective for simultaneous estimation of frusemide and amiloride hydrochloride in tablets.