Simultaneous determination of benazepril hydrochloride and hydrochlorothiazide in tablets by second-order derivative spectrophotometry

A second-order derivative spectrophotometric method for the simultaneous determination of benazepril hydrochloride and hydrochlorothiazide in pharmaceutical dosage forms is described. The determination of benazepril hydrochloride in the presence of hydrochlorothiazide was achieved by measuring the second-order derivative signals at 253.6 and 282.6 nm, while the second-order derivative signal at 282.6 nm was measured for the determination of hydrochlorothiazide. The linear dynamic ranges were 14.80-33.80 microg ml(-1) for benazepril hydrochloride and 18.50-42.20 microg ml(-1) for hydrochlorothiazide, the correlation coefficient for the calibration graphs were better than 0.9998, n = 5, the precision (%RSD) was better than 1.43% and the accuracy was satisfactory (Er < 0.99%). The detection limits were found to be 2.46 and 1.57 microg ml(-1) for benazepril hydrochloride and hydrochlorothiazide, respectively. The method was applied in the quality control of commercial tablets and proved to be suitable for rapid and reliable quality control.     

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.     

Spectrophotometric determination of benazepril in tablets

A simple and sensitive spectrophotometric method has been developed for the determination of benazepril HCl in pharmaceutical formulations. The method is based on the reaction of the drug with potassium permanganate in the presence of sodium hydroxide to produce a bluish-green colored species measurable at 609.4 nm. The absorbance-concentration plot is linear over the range 1-8 microg ml(-1) with minimum detectability of 0.1 microg ml(-1) (2.17 x 10(-7) M). The molar absorptivity was 4.07 x 10(4) l mol(-1) cm(-1) with correlation coefficient (n = 6) of 0.9991. The different experimental parameters affecting the development and stability of the color were studied carefully and optimized. The proposed method was applied successfully to the determination of benazepril in its dosage forms, the percentage recoveries +/- SD (n = 9) were 99.79 +/- 1.40 and 100.50 +/- 1.48 for tablets containing 10 and 20 mg, respectively. The results obtained were in good agreement with those obtained using a reference spectrophotometric method. The proposed method could be applied to the determination of benazepril in presence of the co-formulated drug, hydrochlorothiazide. A proposal of the reaction pathway was presented.     

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%.     

Simultaneous determinations of paeonol and palmatine hydrochloride in Shangshi Aerosols by HPLC method

A simple and rapid HPLC method was described for the simultaneous determination of paeonol and palmatine hydrochloride in Shangshi Aerosols. The optimum separation for these analytes was achieved using the mixture of 0.025 M sodium dihydrogen phosphate-acetonitrile-diethylamine (64:35:1, v/v/v) as the mobile phase and a Nova-Pak((R)) C8 column. The linear ranges of paeonol and palmatine hydrochloride were 0.2-80 and 0.06-60 microg/ml with the regression equations being Y=11716.4+2.96 x 10(6)X (R=0.99969), Y=-6388.8+1.89 x 10(5)X (R=0.99976), and limit of quantifications (LOQ) for paeonol and palmatine hydrochloride were 0.2 and 0.06 microg/ml, respectively (n=6). Other validation parameters: intra-day precision (R.S.D.: 0.71-1.65%) and inter-day precision (R.S.D.: 0.89-2.11%), and reproducibility (recoveries values: 94.6-98.2% for paeonol, 94.85-97.58% for palmatine hydrochloride) were found to be satisfactory. The proposed HPLC method had been applied for the determination of paeonol and palmatine hydrochloride in Shangshi Aerosols; R.S.D. values were 1.45 and 1.13%, respectively. In short, this method was rapid and convenient, which could be used for the routine control of paeonol and palmatine hydrochloride in Shangshi Aerosols.     

Simultaneous determination of moexipril hydrochloride and hydrochlorothiazide in tablets by derivative spectrophotometric and high-performance liquid chromatographic methods

Two new simple and selective assay methods have been presented for the binary mixtures of moexipril hydrochloride (MOEX) and hydrochlorothiazide (HCTZ) in pharmaceutical formulations. The first method depends on second-derivative ultraviolet spectrophotometry with zero-crossing measurements at 215 and 234 nm for MOEX and HCTZ, respectively. The assay was linear over the concentration ranges 1.0-11.0 microg ml(-1) for MOEX and 0.5-9.0 microg ml(-1) for HCTZ. The determination limits for MOEX and HCTZ were found to be 1.0 and 0.5 microg ml(-1), respectively; while the detection limits were 0.2 microg ml(-1) for MOEX and 0.1 microg ml(-1) for HCTZ. The second method was based on isocratic reversed-phase liquid chromatography by using a mobile phase acetonitrile-20 mM phosphate buffer (pH 4.0) (50:50, v/v). Lisinopril was used as an internal standard (IS) and the substances were detected at 212 nm. The linearity range for both drugs was 0.5-12.0 microg ml(-1). The determination and detection limits were found to be 0.100 and 0.010 microg ml(-1) for MOEX and 0.025 and 0.005 microg ml(-1) for HCTZ, respectively. The proposed methods were successfully applied to the determination of these drugs in synthetic mixtures and commercially available tablets with a high percentage recovery, good accuracy and precision.     

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.     

A validated LC method for the determination of clopidogrel in pharmaceutical preparations

A stability indicating, reversed-phase high-performance liquid chromatographic method was developed and validated for the determination of clopidogrel in pharmaceutical dosage forms. The determination was performed on a semi-micro column, BDS C8 (250 x 2.1 mm i.d., 5 microm particle size); the mobile phase consisted of a mixture of 0.010 M sodium dihydrogen phosphate (pH 3.0) and acetonitrile (35:65, v/v), pumped at a flow rate 0.30 ml min(-1). The UV detector was operated at 235 nm. The retention times for clopidogrel and naproxen, which was used as internal standard, were 3.08 and 6.28 min, respectively. Calibration graphs are linear (r better than 0.9991, n=6), in concentration range 1.00-3.00 microg ml(-1) for clopidogrel. The intra- and inter-day RSD values were less than 1.96%, while the relative percentage error E(r) was less than 2.0% (n=5). Detection and quantitation limits were 0.12 and 0.39 micro ml(-1), 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.     

Rapid and sensitive HPLC method for the simultaneous determination of dorzolamide hydrochloride and timolol maleate in eye drops with diode-array and UV detection

A rapid and sensitive HPLC method has been developed for the simultaneous determination of dorzolamide hydrochloride and timolol maleate. The drugs were monitored with a diode-array detector at two fixed wavelengths (lambda = 250.0 nm for dorzolamide hydrochloride and 300.0 nm for timolol maleate). Liquid chromatography was performed on a RP-YMC pack ODS A-132 C18 (5 microm, 15 cm x 6.0 mm) column and the mobile phase consisted of an acetonitrile: phosphate buffer (pH 2.5): methanol (5:85:10 v/v/v) mix and a flow rate of 1.2 ml x min(-1). The linearity of the method ranged between 4.0-45.0 microg x ml(-1) for dorzolamide hydrochloride and and 2.0-20.6 microg x ml(-1) for timolol maleate in binary mixture. The procedure was successfully applied to the determination of these compounds in pharmaceutical preparations and gave a high recovery, good accuracy and precision without any interference by the excipients.     

Simultaneous determination of fexofenadine and its related compounds by HPLC

A simple reversed phase liquid chromatographic (RPLC) method has been developed and subsequently validated for the determination of fexofenadine hydrochloride and its related compounds A and B. The method utilizes a C8 column for the separation and determination of meta-isomer (related compound B). The separation was achieved using an Eclipse XDB C8, 5 microm, 4.6 x 150 mm column and a mobile phase comprising 1% triethylamine phosphate (pH 3.7), acetonitrile and methanol in the ratio 60:20:20 (v/v/v). 5-Methyl 2-nitrophenol has been used as internal standard for the purpose of quantitation of fexofenadine. The described method was linear over a range of 0.7-18.7 microg/ml for related compounds A and B and 60-750 microg/ml for assay of fexofenadine. The relative standard deviation (n=3) was 0.5% for the drug and 3.4% for related compounds. The intermediate precision was 0.79% (n=9) for assay and 5.16% (n=9) for related impurities. The mean recovery of both the related compounds were in the range of 94-103%. Limits of detection (LOD) and quantification (LOQ) for the related compounds A and B were 0.18, 0.12 and 0.56, 0.48 microg/ml, respectively. The precision of the method was checked by F-test using a reported method as reference and the calculated value (1.35) was found to be less than the table value at 95% confidence levels. The obtained results confirm that the method is highly suitable for its intended purpose.     

A validated method for the determination and purity evaluation of benazepril hydrochloride in bulk and in pharmaceutical dosage forms by liquid chromatography

A gradient liquid chromatographic (LC) method has been developed for the determination and purity evaluation of benazepril hydrochloride in bulk and pharmaceutical dosage forms. The method is simple, rapid and selective. 5-Methyl-2-nitro phenol has been used as internal standard. The method is linear in the range of 50-800 microg. The precision for inter and intra-day assay variation of benazepril hydrochloride is below 1.6% RSD. The accuracy determined as relative mean error (RME) for the intra-day assay is within +/- 2.0%. The method is stability indicating, and is useful in the quality control of bulk manufacturing and also in pharmaceutical formulations.     

Simultaneous determination of losartan and hydrochlorothiazide in tablets by high-performance liquid chromatography

A method for the simultaneous determination of losartan potassium and hydrochlorothiazide in tablets is described. The procedure, based on the use of reversed-phase high-performance liquid chromatography, is linear in the concentration range 3.0-7.0 microg ml(-1) for losartan and 0.5-2.0 microg ml(-1) for hydrochlorothiazide, is simple and rapid and allows accurate and precise results. The limit of detection was 0.08 microg ml(-1) for losartan and 0.05 microg ml(-1) for hydrochlorothiazide.     

Rapid and simple methods for quantitative analysis of some antidepressant in pharmaceutical formulations by using first derivative spectrophotometry and HPLC

Two rapid, simple and accurate first derivative spectrophotometry and HPLC method for the determination of nefazodone hydrochloride and sertraline hydrochloride in pharmaceutical formulations are discussed. The first one is a derivative spectrophotometric procedure and the second one is based on a HPLC method with a UV detector. In the first method, first derivative spectrophotometry, nefazodone hydrochloride or sertraline hydrochloride by measurement of their first derivative signals at 241.8-256.7 nm (peak-to-peak amplitude), or 271.6-275.5 nm (peak-to-peak amplitude), respectively. Calibration graphs were established for 10.0-42.0 microg ml(-1) nefazodone hydrochloride, or 8.0-46.0 microg ml(-1) sertraline hydrochloride. In the other method, HPLC, the UV detection was carried out at 265.0 nm (nefazodone hydrochloride) and 270.0 nm (sertraline hydrochloride). The samples were chromatographed on a Supercosil RP-18 column. The mobile phases were methanol:acetonitrile:phosphate buffer at pH 5.5 (10:50:40 v/v/v) (nefazodone hydrochloride) and methanol:phosphate buffer at pH 4.5 (20:80 v/v) (sertraline hydrochloride). The results obtained from first derivative spectrophotometric method were comparable with those obtained by using HPLC. It was concluded that both the developed methods are equally accurate, sensitive, and precision could be applied directly and easily to the pharmaceutical formulations of nefazodone hydrochloride and sertraline hydrochloride, respectively.     

Stability indicating RP-HPLC method for simultaneous determination of amlodipine and benazepril hydrochloride from their combination drug product

A stability indicating reversed-phase HPLC method has been developed and subsequently validated for simultaneous estimation of amlodipine (AM) present as amlodipine besylate (AB), and benazepril hydrochloride (BH) from their combination product. The proposed RP-HPLC method utilizes a Zorbax SB C18, 5 microm, 250 mm x 4.6 mm i.d. column, mobile phase consisting of phosphate buffer and acetonitrile in the proportion of 65:35 (v/v) with apparent pH adjusted to 7.0, and UV detection at 240 nm using a photodiode array detector. AB, BH, and their combination drug product were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analysed by the proposed method. Peak homogeneity data of AM and BH peaks obtained using photodiode array detector, in the stressed sample chromatograms, demonstrated the specificity of the method for their estimation in presence of degradants. The described method was linear over a range of 6-14 microg/ml for AM and 12-28 microg/ml for BH. The mean recoveries were 99.91 and 100.53% for AM and BH, respectively. F-test and t-test at 95% confidence level were used to check the intermediate precision data obtained under different experimental setups; the calculated value was found to be less than critical value.     

HPLC法同时测定百喘朋中盐酸麻黄碱和盐酸苯海拉明的含量

目的 :建立HPLC法同时测定百喘朋中盐酸麻黄碱和盐酸苯海拉明的含量。方法 :采用DiamonsilC18(5μ,4.6mm×150mm)色谱柱 ,流动相为乙腈 -水 -磷酸 (60∶40∶0 1 ,每1000ml含4 0g 十二烷基硫酸钠 ) ,检测波长为254nm ,采用外标法。结果 :盐酸麻黄碱、盐酸苯海拉明的线性范围分别为2 69μg～32.28μg、2 54μg～30.48μg ,回收率 (n=5)分别为100 4 % (RSD=1.1 % )和99 8 % (RSD=0.9 % )。结论 :本法可同时准确测定百喘朋中盐酸麻黄碱和盐酸苯海拉明的含量。     

Application of TLC-densitometry, first-derivative UV-spectrophotometry and ratio derivative spectrophotometry for the determination of dorzolamide hydrochloride and timolol maleate

Three methods are described for the simultaneous determination of dorzolamide hydrochloride (DORZ) and timolol maleate (TIM) in ophthalmic solutions. The first method is based on application of thin layer chromatographic separation of both drugs followed by the densitometric measurements of their spot areas. After separation on silica gel GF(254) plates, using methanol-ammonia 25% (100:1.5 v/v) as the mobile phase, the chromatographic zones corresponding to the spots were scanned at 253 and 297 nm, respectively. The calibration function was established in the ranges of 2-18 microg for DORZ and 0.5-4.5 microg for TIM. The second method depends on first derivative ultraviolet spectrophotometry, with zero-crossing measurement method. The first derivative values D(1) at 250.2 and 312.5 nm were selected for the assay of DORZ and TIM, respectively. Calibration graphs follow Beer's law in the range 10-64 and 2.5-16 microg ml(-1), respectively. The third method is based on ratio first derivative spectrophotometry. The signals in the first derivative of the ratio spectra at 244 and 306.2 nm were selected to determine DORZ and TIM in the mixture and calibration graphs are linear in the range of 5-40 and 5.0-17.5 microg ml(-1), respectively. The proposed methods were successfully applied to the determination of these compounds in synthetic mixtures and in pharmaceutical preparations. The proposed methods are simple, rapid and suitable for quality control application.     

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 micellar LC determination of lidocaine and tolperisone

A micellar liquid chromatography (MLC) procedure was developed for the simultaneous separation and determination of lidocaine hydrochloride (LD HCl) and tolperisone hydrochloride (TP HCl) using a short-column C18 (12.5 mm x 4.6 mm, 5 microm), sodium dodecyl sulfate (SDS) with a small amount of isopropanol, and diode array detector. The optimum conditions for the simultaneous determination of both drugs were 0.075 mol l(-1) SDS-7.5% (v/v) isopropanol with a flow rate of 0.7 ml min(-1) and detection at 210 nm. The LOD (2S/N) of LD HCl was 0.73 ng 20 microl(-1), whereas that of TP HCl was 1.43 ng 20 microl(-1). The calibration curves for LD HCl and TP HCl were linear over the ranges 0.125-500 microg ml(-1) (r(2)=0.9999) and 1.00-500 microg ml(-1) (r(2)=0.9997), respectively. The %recoveries of both drugs were in the range 98-103% and the %RSD values were less than 2. The proposed method has been successfully applied to the simultaneous determination of TP HCl and LD HCl in various pharmaceutical preparations.     

Spectrophotometric determination of benazepril hydrochloride and hydrochlorothiazide in binary mixture using second derivative, second derivative of the ratio spectra and chemometric methods

Different spectrophotometric methods are presented for the simultaneous determination of benazepril hydrochloride and hydrochlorothiazide in pharmaceutical tablets. The first method depends on second derivative (2D) ultraviolet spectrophotometry, with zero crossing and peak to base measurement. The second derivative amplitudes at 214.8 and 227.4 nm were selected for the assay of benazepril hydrochloride and hydrochlorothiazide, respectively. The second method depends on second derivative of the ratio spectra by measurement of the amplitudes at 241.2 and 273.2 nm for benazepril hydrochloride and hydrochlorothiazide, respectively. Chemometric methods, classical least squares and principal component regression, were applied to analyze the mixture. Both the chemometric methods were applied to the zero and first order spectra of the mixture. The proposed methods were successfully applied for the determination of the two drugs in laboratory prepared mixtures and in commercial tablets.     

The effect of enzyme inhibitor and absorption site following [D-ala2, D-leu5]enkephalin oral administration in rats

The effects of enzyme inhibitor, amastatin, and absorption site following intravenous (i.v.) oral (p.o.), jejunal and ileal administration of [D-ala(2), D-leu(5)]enkephalin (YdAGFdL) were investigated in rats. Model dependent and independent pharmacokinetic parameters were obtained and compared. Linear pharmacokinetics of YdAGFdL were evaluated at 0.28 and 500 microg doses for i.v. and at 1, 500, and 1000 microg for p.o. and ileal routes. Plasma samples were collected and assayed for intact YdAGFdL using a radiometric thin layer chromatography. The clearance (CL) and half lives of the distribution and elimination phases following the 0.28 microg (n=6) i.v. dose were 42.7+/-26.2 (S.D.) ml/min, 0.48+/-0.17 min, and 3.98+/-0.92 min, while those of the 500 microg dose (n=6) were 48.0+/-23.3 ml/min, 0.59+/-0.25, and 6.81+/-3.12 min, respectively, suggesting apparent linear kinetics. The CL values were close to the cardiac output of rats (50 ml/min) indicating very rapid elimination from the body. Mean bioavailability (F) values following p.o. (n=15), jejunal (n=4), and ileal (n=16) administration were 0.40+/-0.24% (S.E.), 1.25+/-0.39, and 1.78+/-0.40, respectively, and were not significantly different (p<0.05) among three doses (1, 1000, 5000 microg). The F value of YdAGFdL following ileal administration in the presence of amastatin was 8.76+/-4.47% (n=6), a 22 fold increase over po administration and a five fold increase over ileal administration without an inhibitor. These results indicate that 'effective' oral delivery of small peptides may be achievable.