Validated Spectrophotometric Methods for the Determination of Oxybuprocaine Hydrochloride

Simple, rapid, accurate and reliable spectrophotometric methods were developed and validated for determination of Oxybuprocaine hydrochloride (OXY) in pure form and in pharmaceutical preparation. The methods depend on charge transfer reaction of OXY as n-electron donor with p-chloranilic acid (p-CA), 2, 3 – dichloro 5, 6 – dicyano 1, 4 benzoquinone (DDQ) and iodine as π and σ acceptors, respectively. These reactions were studied under various conditions and the optimum parameters were selected. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9996, 0.9997, and 0.9998) were found between absorbance of the formed complexes and concentrations of OXY in the range of 20.0 - 220.0 μg/mL, 10.0-80.0 μg/mL and 4.0-44.0 μg/mL for (p-CA), DDQ and iodine methods, respectively. The methods were successfully applied for the determination of OXY in pure form and in dosage form. Job’s method was applied to determine the stoichiometry of the reactions. No significant difference was found at p = 0.05 when the obtained results of the proposed methods were statistically compared with those obtained by an official method

Development and validation of HPLC and CE methods for simultaneous determination of amlodipine and atorvastatin in the presence of their acidic degradation products in tablets

Two methods were developed for separation and quantitation of amlodipine (AML) and atorvastatin (ATV) in the presence of their acidic degradation products. The first method was a simple isocratic RP-HPLC method while the second was capillary electrophoresis (CE). Degradation products were obtained by acidic hydrolysis of the two drugs and their structures were elucidated for the first time by IR and MS spectra. Degradation products did not interfere with the determination of either drug and the assays were therefore stability-indicating. The linearity of the proposed methods was established over the ranges 1–50 μg mL–1 for AML and ATV in the HPLC method and in the range of 3–50 and 4–50 μg mL-1 for AML and ATV, respectively, in the CE method. The proposed methods were validated according to ICH guidelines. The methods were successfully applied to estimation of AML and ATV in bulk powder and in pharmaceutical dosage forms

Development and validation of HPLC and CE methods for simultaneous determination of amlodipine and atorvastatin in the presence of their acidic degradation products in tablets

Two methods were developed for separation and quantitation of amlodipine (AML) and atorvastatin (ATV) in the presence of their acidic degradation products. The first method was a simple isocratic RP-HPLC method while the second was capillary electrophoresis (CE). Degradation products were obtained by acidic hydrolysis of the two drugs and their structures were elucidated for the first time by IR and MS spectra. Degradation products did not interfere with the determination of either drug and the assays were therefore stability-indicating. The linearity of the proposed methods was established over the ranges 1-50 μg mL-1 for AML and ATV in the HPLC method and in the range of 3-50 and 4-50 μg mL-1 for AML and ATV, respectively, in the CE method. The proposed methods were validated according to ICH guidelines. The methods were successfully applied to estimation of AML and ATV in combined tablets

Novel stability indicating methods for the determination of certain synthetic estrogen level modifiers

Tamoxifen citrate (TC) and raloxifene hydrochloride (RH) are two selective estrogen receptor modifiers. TC is usually used in the treatment of breast cancer while RH is used in the treatment of osteoporosis. Two stability indicating methods, namely, first derivative of ratio spectra (1DD) and TLC-densitometric method are used for the determination of TC in the presence of its photodegradants and RH in the presence of its oxidative degradants. For the first derivative of ratio spectra method, TC was quantitatively measured at 263 nm and 298.2 nm in a concentration range of 10–60 μg/mL while RH was determined at 267.6 nm in a concentration range of 2–18 μg/mL. In the spectro-densitometric method, TC was separated from its photodegradants using a developing system consisting of acetonitrile: 33% ammonia solution (10: 0.1, v/v) in a concentration range of 6–20 μg/band while RH was separated from its oxidative degradants using ethyl acetate: methanol: 33% ammonia solution (7: 3: 0.1, by volume) as a developing system in a concentration range of 3–11 μg/band. The two methods were successfully applied for the stability indicating the determination of the two drugs in a pure powdered form and a pharmaceutical dosage form and showing good recoveries. Statistical comparison between the results obtained by applying the proposed methods and the official method or the reported method for TC and RH, respectively was done and no significant difference was found at p = 0.05

Sequential Spectrophotometric Method for the Simultaneous Determination of Amlodipine, Valsartan, and Hydrochlorothiazide in Coformulated Tablets

A new, simple and specific spectrophotometric method was developed and validated in accordance with ICH guidelines for the simultaneous estimation of Amlodipine (AML), Valsartan (VAL), and Hydrochlorothiazide (HCT) in their ternary mixture. In this method three techniques were used, namely, direct spectrophotometry, ratio subtraction, and isoabsorptive point. Amlodipine (AML) was first determined by direct spectrophotometry and then ratio subtraction was applied to remove the AML spectrum from the mixture spectrum. Hydrochlorothiazide (HCT) could then be determined directly without interference from Valsartan (VAL) which could be determined using the isoabsorptive point theory. The calibration curve is linear over the concentration ranges of 4–32, 4–44 and 6–20 μg/mL for AML, VAL, and HCT, respectively. This method was tested by analyzing synthetic mixtures of the above drugs and was successfully applied to commercial pharmaceutical preparation of the drugs, where the standard deviation is <2 in the assay of raw materials and tablets. The method was validated according to the ICH guidelines and accuracy, precision, repeatability, and robustness were found to be within the acceptable limits

Development and validation of two chromatographic methods for the simultaneous determination of raubasine and almitrine besmesylate in pharmaceutical dosage form

A binary mixture of almitrine besmesylate (A) and raubasine (R) was determined by two different chromatographic methods. The first method was based on HPTLC separation of the two drugs followed by densitometric measurement of their spots at 245 and 285 nm for A and R, respectively. The separation was carried out using HPTLC silica gel F254 nanoplates with methanol:ammonia (10:8, v/v) as developing solvent. The linearity was achieved over concentration range of 0.5–8 μg/spot and 0.5–10 μg/spot with mean accuracy 100.79 ± 1.58 and 100.68 ± 1.78, for A and R, respectively. The second method involved the determination of A and R using reversed phase high performance liquid chromatography (HPLC) on C18 column using acetonitrile:potassium dihydrogen orthophosphate buffer pH = 4.7 (70:30, v/v) as mobile phase with flow rate at 2 ml/min. Quantitation was achieved using UV detection at 220 nm. A linear relationship was obtained over a concentration range of 0.75–105 μg ml−1 for both drugs with mean accuracy 100.85 ± 1.74 and 98.82 ± 1.31, for A and R, respectively. The methods were successfully applied for the determination of the cited drugs in dosage forms. The proposed methods were validated according to USP and were found to be valid and suitable for the assay of the cited drugs in dosage forms in quality control laboratories

Adsorptive Removal of Fluoroquinolones from Water by Pectin-Functionalized Magnetic Nanoparticles: Process Optimization Using a Spectrofluorimetric Assay

The efficiency of adsorption of two photosensitive fluoroquinolones; Ciprofloxacin (CIP) and Moxifloxacin (MOX), on the surface of synthesized magnetite/pectin nanoparticles (MPNPs) and magnetite/silica/pectin nanoparticles (MSPNPs) was studied from aqueous solution under varying experimental conditions. A validated spectrofluorimetric assay was developed for monitoring of CIP and MOX intact drugs and their photodegraded molecules concentrations. To optimize the working conditions which influence the drugs sorption, a 2⁴ full factorial experimental design was implemented. The maximum percentage of removal was attained as 89% (type of sorbent = MSPNPs, pH = 7.0, initial drug concentration = 5 mg/L, and contact time = 30 min). The studied factorspH, NPs loading, initial drug concentration, and contact timewere significant for both types of sorbents. The most significant variable was pH, and the highest CIP and MOX adsorption occurred at pH = 7.0. Equilibrium isotherm data were fitted to Langmuir, Freundlich, and Sips equations, and the Sips model showed the best fit with equilibrium isotherm data. Furthermore, pseudo-first- and pseudo-second-order kinetic models were used to analyze sorption kinetics, and it was found that adsorption of the investigated fluoroquinolones followed pseudo-second-order kinetics. We believe that our synthesized NPs can be used as effective adsorbents for fluoroquinolones and their photodegraded molecules removal from aqueous solutions