Mohie K. Sharaf El-Din

Validated stability-indicating spectrofluorimetric methods for the determination of ebastine in pharmaceutical preparations

Two sensitive, selective, economic, and validated spectrofluorimetric methods were developed for the determination of ebastine (EBS) in pharmaceutical preparations depending on reaction with its tertiary amino group. Method I involves condensation of the drug with mixed anhydrides (citric and acetic anhydrides) producing a product with intense fluorescence, which was measured at 496 nm after excitation at 388 nm.Method (IIA) describes quantitative fluorescence quenching of eosin upon addition of the studied drug where the decrease in the fluorescence intensity was directly proportional to the concentration of ebastine; the fluorescence quenching was measured at 553 nm after excitation at 457 nm. This method was extended to (Method IIB) to apply first and second derivative synchronous spectrofluorimetric method (FDSFS & SDSFS) for the simultaneous analysis of EBS in presence of its alkaline, acidic, and UV degradation products.The proposed methods were successfully applied for the determination of the studied compound in its dosage forms. The results obtained were in good agreement with those obtained by a comparison method. Both methods were utilized to investigate the kinetics of the degradation of the drug.

Simultaneous Determination of Acetaminophen with Orphenadrine Citrate, Ibuprofen or Chlorzoxazone in Combined Dosage Forms by Zero-Crossing Derivative Spectrophotometry

Abstract A derivative spectrophotmetric procedure for the simultaneous determination of acetaminophen-orphenadrine citrate, acetaminophen-ibuprofen and acetaminophen-chlorzoxazone, binary mixtures is described. The procedure minimises the mutual interference between these drugs in mixtures and allows the determination of these compounds without a previous extraction step. The precision of the method, expressed as the relative standard deviation, is better than 4%. The method has been successfully applied to laboratory mixtures and commercial tablets containing these drugs.

Colorimetric determination of simvastatin and lovastatin in pure form and in pharmaceutical formulations.

Simple, accurate and precise colorimetric method for the determination of simvastatin and lovastatin in tablets is described. The method is based on the reaction of simvastatin or lovastatin with hydroxylamine in alkaline medium to form the corresponding hydroxamic acid derivatives which, on treatment with ferric ion in acid medium, yield highly colored ferric-chelate complex with maximum absorption at 513nm. Beers law is obeyed in the concentration ranges 0.04-0.4mgml(-1) for both simvastatin and lovastatin, respectively. Molar absorptivity values, as calculated from Beers law data, were found to be 1.15x10(3) and 1.09x10(3)lmol(-1)cm(-1) for simvastatin and lovastatin, respectively. Optimal experimental parameters for the reaction have been studied. The validity of the described procedures was assessed. Statistical analysis of the results reflects that the proposed procedures are precise, accurate and easily applicable for the determination of simvastatin and lovastatin in pure form and in pharmaceutical preparation.

Validated spectrofluorimetric method for the determination of atorvastatin in pharmaceutical preparations

A rapid, sensitive and simple spectrofluorimetric method was developed for the estimation of atorvastatin. In this method, the native fluorescence characteristics of atorvastatin have been studied in both acidic and basic media. High sensitivity was obtained with 5% acetic acid at 389 nm using 276 nm for excitation. Regression analysis showed a good correlation coefficient (r=0.9995) between fluorescence intensity and concentration over the range of 1.5–4 μg/mL with detection limit of 0.012 μg/mL. The proposed method was successfully applied to the analysis of atorvastatin in pure and pharmaceutical dosage forms with average recovery of 100.29±0.47%. The results were compared favorably with those of the reported method.

Derivative Spectrophotometric and Liquid Chromatographic Methods for the Simultaneous Determination of Metoclopramide Hydrochloride and Aspirin in Pharmaceuticals

Two simple analytical methods were developed and validated for the analysis of a binary mixture of metoclopramide (MET) and aspirin (ASP). The first method depends on measuring the first derivative amplitudes at 257 nm for MET and at 310 nm for ASP, respectively. The calibration graphs were linear in the range of 0.25-20.0 µg/mL for MET and 10.0-200.0 µg/mL for ASP. For the second method, good chromatographic separation was achieved using Promosil C18 column (250 × 4.6 mm i.d., 5 µm particle size). Mobile phase consisting of methanol and 0.02 M phosphate buffer in the ratio of 60:40 (v/v) at pH 4.0 was pumped at a flow rate of 1 mL/min with UV detection at 260 nm. Indapamide was used as an internal standard. The method showed good linearity over the concentration ranges of 0.20-10.0 and 10.0-200.0 μg/mL with limits of detection of 0.06, 1.81 μg/mL and limits of quantification of 0.17, 5.46 μg/mL for MET and ASP, respectively. The results of the proposed methods were statistically compared with those obtained by the official United States Pharmacopeia method revealing non-significant differences in the performance of the methods regarding accuracy and precision. The suggested methods were successfully applied for the simultaneous analysis of the studied drugs in their co-formulated tablets as well as in their single dosage forms.

Determination of Two Ternary Mixtures for Migraine Treatment Using HPLC Method with Ultra Violet Detection

New, selective, and accurate HPLC methods are described for the analysis of two ternary mixtures used for migraine treatment containing drotaverine hydrochloride (DRT) with caffeine (CAF), and dipyrone (DIP) (mixture I), or paracetamol (PAR) (mixture II). The described methods used a mobile phase consisting of methanol: 0.02 M sodium dihydrogen phosphate in two different ratios. The pH of the mobile phases was adjusted to 4 and UV detection at 220 nm was used. Good chromatographic separations were achieved using Promosil C18 column. Spironolactone (SPL) and propranolol (PRP) were used as internal standards (ISs) for mix. I and II, respectively.

Simultaneous determination of four vasoactive phytochemicals in different pharmaceutical preparations by a simple HPLC-DAD method

A new, simple isocratic HPLC method was developed and validated for the simultaneous estimation of four vasoactive phytochemicals: ascorbic acid (ASC), rutin (RUT), hesperidin (HSP), and diosmin (DSM) in different pharmaceutical preparations. Separation of the four compounds was achieved in about 8 min on a phenomenex-C18 column (250 mm × 4.6 mm, 5 μm particle size) using a mobile phase consists of 50 mM phosphate buffer (pH 4.0) : acetonitrile (75 : 25, v/v) eluted at 1.0 mL min−1 with diode array detection at 275 nm. Linear correlation was obeyed over the concentration ranges of 2.0–60.0, 1.0–20.0, 2.0–50.0, and 5.0–100.0 μg mL−1 for ASC, RUT, HSP, and DSM, respectively. The developed method is efficient, reproducible and appropriate as a versatile method for quality control of various combinations of these drugs in different pharmaceutical preparations with high values of %recoveries which agreed well with the labeled claim. The method is also a stability-indicating one for DSM in its pure state and single-component tablets. A comparison of the results obtained by the developed method with those of the comparison methods confirmed no significant differences between them with respect to accuracy and precision.

Enhanced spectrofluorimetric determination of esomeprazole and pantoprazole in dosage forms and spiked human plasma using organized media

A simple, sensitive and rapid spectrofluorimetric method was developed for the determination of esomeprazole (EMZ) and pantoprazole (PRZ) in their pharmaceutical formulations and human plasma. The proposed method is based on the fluorescence spectral behavior of EMZ in methanol in the presence of 0.1 m NaOH containing 0.5% methyl cellulose (MC) at 306/345 nm. The fluorescence intensity of EMZ was enhanced about 1.3-fold and good linearity in the range 0.4-4.0 µg/mL with a lower detection limit of 0.04 µg/mL and lower quantification limit of 0.14 µg/mL. For PRZ, its methanolic solution exhibited marked native fluorescence at 290/325 nm after enhancement (about 2.1- or 1.4-fold) using either 0.025% sodium dodecyl sulfate (SDS) or 0.05% MC in the presence of 0.2 m borate buffer of pH 9.5. The fluorescence-concentration plots of PRZ were rectilinear over the ranges 0.2-2.0 and 0.3-3.0 µg/mL with lower detection limits of 0.02 and 0.03 µg/mL and lower quantification limits of 0.07 and 0.09 µg/mL using sodium dodecyl sulfate and MC, respectively. The method was successfully applied to the analysis of EMZ and PRZ in their commercial dosage forms and the results were in good agreement with those obtained with the comparison method. Furthermore, in a preliminary investigation, the proposed method was extended to the in vitro determination of the two drugs in spiked human plasma and the results were satisfactory.

MICELLAR LIQUID CHROMATOGRAPHIC DETERMINATION OF RIBAVIRIN, SILYBIN, INTERFERON α 2A, LAMIVUDINE, AND URSODEOXYCHOLIC ACID IN DOSAGE FORMS AND BIOLOGICAL FLUIDS

□ A simple, reversed phase high performance liquid chromatographic method has been developed for the determination of ribavirin, silybin, interferonα2a, lamivudine, and ursodeoxycholic acid in pharmaceutical preparations, human plasma, and urine. The method was conducted using A Shim-pack VP-ODS (150×4.6 mm i.d) stainless steel column at ambient temperature with ultraviolet (UV) detection at 214 nm. Micellar mobile phase is consisting of of 0.1 M sodium dodecyl sulphate, 8%n-propanol, 0.3%triethylamine in 0.02 M phosphoric acid (pH 6.0) was used and it was pumped at a flow rate of 0.8 mL/min. The calibration curve was rectilinear over the concentration range of 0.01–0.1μg/mL, 0.01–0.2 µg/mL, 0.1–1.0 µg/mL, 0.05–1.0 µg/mL, and 0.01–0.5 µg/mL for ribavirin, silybin, interferonα2a, lamivudine, and ursodeoxycholic acid, respectively. The proposed method was successfully applied to the analysis of these drugs in some dosage forms. The method was extended to the in vitro, in vivo determination of these drugs in spiked human plasma samples with the mean%recoveries of 99.17 ± 1.10, 99.10 ± 0.88, 98.9 ± 0.80, and 99.10 ± 0.88 for ribavirin, silybin, lamivudine, and ursodeoxycholic acid, respectively.

Micellar liquid chromatographic method for the simultaneous determination of Levofloxacin and Ambroxol in combined tablets: Application to biological fluids

BackgroundLevofloxacin hemihydrate (LEV) and ambroxol HCl (AMB) are available for the treatment of upper and lower respiratory tract infections. A survey of the literature reveals that two reversed phase HPLC methods were e reported for the simultaneous determination of LEV and AMB in pharmaceutical preparations. However the reported methods suffers from the low sensitivity, no application of the method in the combined tablets and no application to biological fluids. Also the toxic effects of the used solvents which are harmful to human beings. For this reason, our target was to develop a simple sensitive, less hazardous micellar HPLC method for the simultaneous determination of LEV and AMB in their combined dosage forms and plasma.ResultsThe method showed good linearity over the ranges of 1–44 μg/mL and 1–20 μg/mL with limits of detection 0.26 and 0.07 μg/mL and limits of quantification 0.80 and 0.20 μg/mL for LEV and AMB, respectively. The method was further extended to the determination of LEV in spiked human plasma with mean percentage recoveries of 100.10% ± 1.14 as well as determination of LEV in real human plasma without prior extraction. Statistical evaluation of the data was performed according to ICH Guidelines.ConclusionThe 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 combined tablets were 100.20 ± 1.64 and 100.72 ± 1.11 for LEV and AMB, respectively and 100.10 ± 1.14 for LEV in spiked human plasma. Statistical comparison of the results with those of the comparison method revealed good agreement and proved that there were no significant difference in the accuracy and precision between the two methods respectively.