Muhammad Ashfaq

Global risk of pharmaceutical contamination from highly populated developing countries

Global pharmaceutical industry has relocated from the west to Asian countries to ensure competitive advantage. This industrial relocation has posed serious threats to the environment. The present study was carried out to assess the possible pharmaceutical contamination in the environment of emerging pharmaceutical manufacturing countries (Bangladesh, China, India and Pakistan). Although these countries have made tremendous progress in the pharmaceutical sector but most of their industrial units discharge wastewater into domestic sewage network without any treatment. The application of untreated wastewater (industrial and domestic) and biosolids (sewage sludge and manure) in agriculture causes the contamination of surface water, soil, groundwater, and the entire food web with pharmaceutical compounds (PCs), their metabolites and transformed products (TPs), and multidrug resistant microbes. This pharmaceutical contamination in Asian countries poses global risks via product export and international traveling. Several prospective research hypotheses including the development of new analytical methods to monitor these PCs/TPs and their metabolites, highly resistant microbial strains, and mixture toxicity as a consequence of pharmaceutical contamination in these emerging pharmaceutical exporters have also been proposed based on the available literature.

HPLC DETERMINATION OF EZETIMIBE AND SIMVASTATIN IN PHARMACEUTICAL FORMULATIONS

ABSTRACT A simple, precise and sensitive reverse-phase high performance liquid chromatographic method was developed and validated for the simultaneous determination of ezetimibe and simvastatin in pharmaceutical formulations. Chromatographic separation was performed on a Merck C18 column at a wavelength of 240 nm using a mixture of 0.1M ammonium acetate buffer pH 5.0 and acetonitrile in the ratio of (30:70, v/v). The method results in excellent separation with good resolution between the two analytes. The within day variation was between 0.28 and 1.10 % and between day variation was between 0.56 and 1.32 %. The recovery was greater than 99.12 % with RSD less than 1.38 %. The method was validated according to ICH guidelines by performing linearity, accuracy, precision, limits of quantitation and selectivity. The results show that the method is suitable for its intended use.Key words: HPLC, acetonitrile, isocratic, ezetimibe, simvastatin.Corresponding author: e-mail: ashfaqchemist@hotmail.com

SIMULTANEOUS QUANTITATION OF OLMESARTAN MEDOXOMIL AND AMLODIPINE BESYLATE IN COMBINED TABLETS USING HPLC

ABSTRACT A simple, sensitive and isocratic reverse phase high performance liquid chromatographic (RP-HPLC) method has been developed for the simultaneous determination of olmesartan medoxomil and amlodipine in pharmaceutical tablet formulations. HPLC analysis was carried out using reverse phase isocratic elution with a C18 column and a mobile phase of 0.05 M ammonium acetate pH 6.8 and acetonitrile in the ratio of 40:60, v/v. Detection of the analytes was achieved using UV detector at 239 nm. The retention times of olmesartan medoxomil and amlodipine were 2.50 and 3.94 respectively. Linearity of the method was found to be in the concentration range of 16-112 µgml -1 for olmesartan medoximil and 4-28 µgml for amlodipine. The correlation coefficient value was greater than 0.9999 for both the analytes. The method is suitable for the estimation of both the components simultaneously in pharmaceutical tablet formulations. Key words: HPLC, acetonitrile, olmesartan, amlodipine e-mail: ashfaqchemist@hotmail.com

Development and validation of a high performance liquid chromatographic method for the simultaneous determination of potassium clavulanate and cefadroxil in synthetically prepared tablets

A simple, sensitive and rapid high performance liquid chromatographic method was developed and validated for the simultaneous determination of potassium clavulanate and cefadroxil in synthetically prepared tablets. Chromatographic separation and detection was carried out on a C-18 column using 0.05 M potassium dihydrogen phosphate buffer (pH 5.0) and acetonitrile in the ratio of 94: 06 (v/v) as mobile phase at wavelength of 225 nm. The method was linear in the concentration range of 3.75–22.5 μg/mL for potassium clavulanate and 15–90 μg/mL for cefadroxil. The flow rate was 1.0 mL/min and the total analysis time was less than 10 min. The mean recoveries was found to be greater than 99% with RSD less than 1.0%. The proposed method was validated by performing linearity, recovery, specificity, robustness, LOD/LOQ and within-day and between-day precision. The chromatographic results obtained from the synthetically prepared tablets show that the method is highly precise and accurate for the simultaneous quantitation of clavulanate potassium and cefadroxil.

Determination of glimepiride in pharmaceutical formulations using HPLC and first-derivative spectrophotometric methods

Two validated analytical methods have been developed to determine glimepiride in pharmaceutical formulations using HPLC and 1st order derivative spectrophotometric techniques. Employing reverse phase HPLC method, the drug was analyzed by pumping a mixture of acetonitrile and 2% formic acid solution, pH 3.5 (80: 20 v/v) through a C18 column (250 × 4.6 mm, 5 μm) and detecting the eluents at 228 nm. The linearity range was found to be 20–140 μg/mL with mean recovery of 100.52 ± 0.33%. The second method was based on the formation of a complex of the drug with 2,3,5-triphenyl-2H-tetrazolium chloride in basic media. 1st order derivative spectrum made it possible to detect the complex at 413.5 nm. The linearity range was found to be 40–160 μg/mL, with mean recovery of 100.33 ± 0.47%. Both the proposed methods can reliably be used for routine analysis of glimepiride in raw material as well as in pharmaceutical formulations.

DEVELOPMENT AND VALIDATION OF LIQUID CHROMATOGRAPHIC METHOD FOR NAPROXEN AND ESOMEPRAZOLE IN BINARY COMBINATION

The present study reports the development and validation of a simple, economic and sensitive HPLC method for the concurrent determination of naproxen and esomeprazole in pharmaceutical formulations. Isocratic chromatography was performed with C-18 column and mixture of phosphate buffer (pH 6.1) and acetonitrile in ratio of (40:60, v/v) at 1.5 mlmin-1. The eluents were monitored at 302 nm using UV detector. The method was isocratic in the range of 9.38 to 300 µgml-1 for naproxen and 0.5 to 16 µgml-1 for esomeprazole. Validation of the method was performed by testing parameters like linearity, accuracy, precision, robustness, specificity, LOD and LOQ values. In the specificity the drugs were subjected to forced degradation studies like acidic, basic, oxidative and thermal stresses. Both the analytes were separated within three minutes. As the method separates the degradation products produced during forced degradation studies from the active analytes so it can be used not only for regular determination of naproxen and esomeprazole but also for their stability studies.

DEVELOPMENT AND VALIDATION OF LIQUID CHROMATOGRAPHIC METHOD FOR GATIFLOXACIN AND KETOROLAC TROMETHAMINE IN COMBINED DOSAGE FORM

A fast, sensitive, and accurate stability indicating reverse phase high performance liquid chromatographic (RP-HPLC) method was developed and validated for simultaneous determination of gatifloxacin and ketorolac tromethamine in combined dosage form. Chromatographic separations were achieved on BDS Hypersil C8 column (250 × 4.6 mm) with mobile phase that consisted of methanol and phosphate buffer (pH 3.0) in the ratio of (55:45 v/v) at a flow rate of 1.5 m Lmin−1. The analytes were detected at 270 nm using ultraviolet detection. The retention times of gatifloxacin and ketorolac tromethamine were found to be 2.460 and 6.366 min, respectively. When forced degradation studies were applied to both the drugs in combination, it was found that both gatifloxacin and ketorolac tromethamine were very stable under the basic, acidic, wet heat and oxidative environment. The method was linear in the concentration range of 30–90 µg mL−1 for gatifloxacin and 50–110 µg mL−1 for ketorolac tromethamine. The correlation coefficients were found to be 0.9998 and 0.9999 for gatifloxacin and ketorolac tromethamine, respectively. The method resulted in good separation of both the analytes with acceptable tailing and resolution. The developed method can be used for routine determination of gatifloxacin and ketorolac tromethamine in commercial formulations.

DEVELOPMENT AND VALIDATION OF LIQUID CHROMATOGRAPHIC METHOD FOR THE SIMULTANEOUS ESTIMATION OF EZETIMIBE AND LOVASTATIN IN HUMAN PLASMA

In the present study conditions were optimized for the development and validation of a simple, sensitive and isocratic reverse phase high performance liquid chromatographic method for the simultaneous determination of ezetimibe and lovastatin in human plasma using gemfibrozil as internal standard. After a single step extraction with acetonitrile, satisfactory elution of both the analytes along with internal standard was achieved on a Merck C-18 column using a mixture of 0.1 M ammonium acetate pH 5.0 and acetonitrile in the ratio of (28:72, v/v) at a flow rate of 1.5 ml/min. The detection was carried out at a wavelength of 240 nm using a photodiode array detector. The method was linear in the concentration range of 0.2-25 |xg/ml for ezetimibe and 0.4-50 |xg/ml for lovastatin. The extraction recovery of analytes was greater than 85 % and within day and between day precision was also satisfactory. The method was validated by performing its linearity, recovery, precision, LOD/LOQ values and stability of solutions. The total eluting time for the analysis is less than twelve minutes. As the plasma peaks did not interfere with the peaks of analytes so the method can be used for the determination of ezetimibe and lovastatin in human plasma and may possibly be for the pharmacokinetic study.

DEVELOPMENT AND VALIDATION OF LIQUID CHROMATOGRAPHIC METHOD FOR GEMFIBROZIL AND SIMVASTATIN IN BINARY COMBINATION

ABSTRACT A simple, sensitive and validated HPLC method has been developed to determine gemfibrozil and simvastatin simultaneously in synthetic mixture form. Chromatographic separation was achieved on a C-18 column using a mixture of 0.1 M ammonium acetate pH 5.0 and acetonitrile in the ratio of 15:85 (v/v) at a wavelength of 237 nm. Linearity of the method was found to be in the concentration range of 60-420 µg/ml for gemfibrozil and 1-7 µg/ml for simvastatin with correlation coefficient greater than 0.9999. The total eluting time for the two components is less than ten minutes. The method can be used for simultaneous determination of gemfibrozil and simvastatin.Key words: HPLC, acetonitrile, gemfibrozil, simvastatine-mail: ashfaqchemist@hotmail.com INTRODUCTION Gemfibrozil (Fig. 1) chemically designated as 5-(2,5-dimethylphenoxy)-2,2-dimethylpentanoic acid is a cholesterol-lowering agent. It has been found effective not only for reducing serum cholesterol, triglyceride, and LDL levels, but also effective for increasing serum HDL levels [1]. It has also been demonstrated that this drug lowers the incidence of coronary heart disease in humans [2-3]. A number of analytical methods have been developed for its determination in pharmaceutical formulations or in biofluids either alone or in combination with other drugs. These include determination of gemfibrozil by liquid chromatography–tandem mass spectrometry [4], HPLC [5-13], flow injection and spectrofluorimetric analysis [14-15]. Simvastatin (Fig. 2), a hypolipidemic drug belonging to the class of pharmaceuticals called statins is chemically designated as [(1S,3R,7R,8S,8aR)-8-[2-[(2R,4R)-4-hydroxy-6-oxo-oxan-2-yl]ethyl]-3,7-dimethyl-1,2,3,7,8,8a-hexahydronaphthalen-1-yl] 2,2-dimethylbutanoate. It is used for the treatment of hypercholesterolemia [16]. Following conversion of this lactone prodrug to its hydroxyl acid form, the compound is a potent competitive inhibitor of HMG-CoA reductase, the rate limiting enzyme in cholesterol biosynthesis [17]. Different analytical methods have been reported for the determination of simvastatin, which include HPLC [18-21], HPLC-MS/MS [22], derivative spectrophotometry [23] and Voltammetric techniques [24]. Combination of statins with fibrates can be used for combined dyslipidemia and it can decrease low density lipoprotein cholesterol more than 40 % [33]. Controlled trials have not only shown regression of atherosclerotic lesions with this combination, but have also demonstrated increased risk of myopathy [34-35]. Experts believe myopathy risk is greater with gemfibrozil as compared to fenofibrate, [36]. The maximum approved daily doses of lovastatin, simvastatin and rosuvastatin are therefore lowered (20, 10 and 10 mg, respectively) when used with gemfibrozil [37].According to the information collected from literature there is no reported method for simultaneous determination of gemfibrozil and simvastatin. In the present work we are therefore focused on to achieve the optimum chromatographic conditions for the simultaneous determination of gemfibrozil and simvastatin in a synthetic mixture. We describe in this paper a simple, sensitive and validated HPLC method with total run time less than ten minutes for the simultaneous determination of gemfibrozil and simvastatin. The developed method can be applied successfully to quality control and for other analytical purposes.

Stability indicating HPLC method for the simultaneous determination of ofloxacin and ketorolac tromethamine in pharmaceutical formulations

A simple, specific and accurate stability indicating liquid chromatographic method is established for simultaneous determination of ofloxacin and ketorolac tromethamine in bulk drugs and pharmaceutical formulations. Optimum chromatographic separations among ofloxacin, ketorolac and stress-induced degradation products have been achieved within 15 min by using a BDS Hypersil C8 column (250 × 4.6 mm, 5 μm) as the stationary phase with methanol and phosphate buffer pH 3.0 (55:45 v/v) as the mobile phase at a flow rate of 0.8 mL min−1. Detection is performed at 270 nm using a diode array detector. The method is validated in accordance with ICH guidelines. The response is a linear function of concentration over the range of 12–84 μg mL−1 for ofloxacin and 20–140 μg mL−1 for ketorolac tromethamine. The method results in excellent separation of analytes and their stress induced degradation products with acceptable tailing and resolution. The peak purity index for both the analytes after all types of stress is >0.999 indicating complete separation of both analyte peaks from the stress induced degradation products. The method can therefore be regarded as stability-indicating. The developed method can be applied successfully for simultaneous determination of ofloxacin and ketorolac in pharmaceutical formulations and their stability studies.