Nouruddin W. Ali

Simultaneous HPTLC and RP‐HPLC methods for determination of bumadizone in the presence of its alkaline‐induced degradation product

Accurate, selective, sensitive and precise HPTLC-densitometric and RP-HPLC methods were developed and validated for determination of bumadizone calcium semi-hydrate in the presence of its alkaline-induced degradation product and in pharmaceutical formulation. Method A uses HPTLC-densitometry, depending on separation and quantitation of bumadizone and its alkaline-induced degradation product on TLC silica gel 60 F(254) plates, using hexane-ethyl acetate-glacial acetic acid (8:2:0.2, v/v/v) as a mobile phase followed by densitometric measurement of the bands at 240 nm. Method B comprises RP-HPLC separation of bumadizone and its alkaline-induced degradation product using a mobile phase consisting of methanol-water-acetonitrile (20:30:50, v/v/v) on a Phenomenex C(18) column at a flow-rate of 2 mL/min and UV detection at 235 nm. The proposed methods were successfully applied to the analysis of bumadizone either in bulk powder or in pharmaceutical formulation without interference from other dosage form additives, and the results were statistically compared with the established method.

Validated stability indicating methods for determination of nitazoxanide in presence of its degradation products

Three sensitive, selective and reproducible stability-indicating methods are presented for determination of nitazoxanide (NTZ), a new anti-protozoal drug, in presence of its degradation products. Method A utilizes the first derivative of ratio spectra spectrophotometry by measurement of the amplitude at 364.4 nm using one of the degradation products as a divisor. Method B is a chemometric-assisted spectrophotometry, where principal component regression (PCR) and partial least squares (PLS) were applied. These two approaches were successfully applied to quantify NTZ in presence of degradation products using the information included in the absorption spectra in the range 260–360 nm. Method C is based on the separation of NTZ from its degradation products followed by densitometric measurement of the bands at 254 nm. The separation was carried out on silica gel 60F254, using chloroform–methanol–ammonia solution–glacial acetic acid (95:5:1:1 by volume, pH=5.80) as a developing system. These methods are suitable as stability-indicating methods for the determination of NTZ in presence of its degradation products either in bulk powder or in pharmaceutical formulations. Statistical analysis of the results has been carried out revealing high accuracy and good precision.

Simultaneous determination of methocarbamol and ibuprofen or diclofenac potassium using mean centering of the ratio spectra method

Simultaneous determination of methocarbamol and ibuprofen or diclofenac potassium using mean centering of the ratio spectra method Accurate and sensitive methods were developed for simultaneous determination of methocarbamol and ibuprofen or diclofenac potassium in their binary mixtures, and in the presence of a methocarbamol related substance (guaifenesin) using mean centering of the ratio spectra method. The results obtained were statistically compared with the reported HPLC methods; no significant difference between the proposed methods and the reported methods was found regarding either accuracy or precision. Simultano određivanje metokarbamola i ibuprofena ili diklofenak kalija metodom centriranja srednjih vrijednosti spektralnih omjera (mean centering of the ratio spectra method) U radu su opisane točne i osjetljive metode za simultano određivanje metokarbamola i ibuprofena ili diklofenak kalija u njihovim binarnim smjesama, te u prisutnosti gvajfenezina, supstancije srodne metokarbamolu koristeći metodu centriranja srednjih vrijednosti spektralnih omjera. Dobiveni rezultati su statistički uspoređeni s objavljenim HPLC metodama. Nije pronađena značajna razlika u točnosti i preciznosti između predložene metode i objavljenih metoda.

Validated Stability Indicating TLC-Densitometric Method for the Determination of Diacerein

This work presents an accurate, sensitive and selective thin-layer chromatography-densitometry method for the simultaneous determination of diacerein in the presence of rhein, the active metabolite and hydrolytic degradation product of diacerein, and emodin, the diacerein impurity, in bulk powder and different pharmaceutical formulations. Chromatographic separation was performed on aluminum plates precoated with 60 F254 silica gel using hexane-ethyl acetate-acetic acid (60:40:0.8, by volume) as a developing system and with detection at 230 nm. The retention factor values of diacerein, rhein and emodin were 0.12, 0.44 and 0.6, respectively. The method was successfully applied for the determination of these compounds with high sensitivity; the linearity ranges were found to be 0.5-10 µg/band (for diacerein and rhein) and 0.5-7 µg/band (for emodin). The developed method was validated according to International Conference on Harmonization guidelines and was applied for the determination of diacerein in different pharmaceutical formulations. Moreover, a statistical comparison between the results of the developed method and those of the reported reversed-phase high-performance liquid chromatography method showed no significant differences. This method can be used for the routine analysis of diacerein, rhein and emodin in quality control laboratories.

Simultaneous determination of methocarbamol and its related substance (Guaifenesin) in two ternary mixtures with ibuprofen and diclofenac potassium by HPTLC spectrodensitometric method

Accurate, sensitive, and precise high-performance thin-layer chromatographic (HPTLC) method was developed and validated for the determination of Methocarbamol (ME) and its related substance (guaifenesin (GU)) in two ternary mixtures with ibuprofen (IB) and diclofenac potassium. The method depends on separation and quantification of the studied drugs on TLC silica gel 60 F254 plates using ethyl acetate-acetone-triethylamine-formic acid (62:35:6:0.3, by volume) as the developing system followed by densitometric measurement of the bands at 222 nm for the first mixture containing methocarbmol, IB, and GU and at 278 nm for the second mixture containing methocarbmol, diclofenac potassium, and GU. The proposed methods were successfully applied for the determination of ME, IB, and diclofenac potassium in the presence of ME-related substance (GU) either in bulk powder or in their pharmaceutical formulations.

Kinetic study and mechanism of Niclosamide degradation

A spectrophotometric kinetic study of Niclosamide alkaline degradation as a function of drug concentration, alkaline concentration and temperature has been established utilizing double divisor-ratio spectra spectrophotometric method. The developed method allowed determination of Niclosamide in presence of its alkaline degradation products; namely; 2-chloro-4-nitro aniline (DEG I) and 5-chloro salicylic acid (DEG II) with characterization of its degradation mechanism. It was found that degradation kinetic of Niclosamide followed pseudo-first order under the established experimental conditions with a degradation rate constant (k) of 0.0829 mol/h and half life (t1/2) of 8.35 h. The overall degradation rate constant as a function of the temperature under the given conditions obeyed Arrhenius equation where the activation energy was calculated to be 3.41 kcal/mol.

Development and Validation of Different Chromatographic Methods for Determination of Two Hypouricemic Drugs in Their Combined Dosage Form

Two sensitive, selective and precise chromatographic methods have been developed, optimized and validated for Allopurinol (ALP) and Benzbromarone (BENZ) determination in their pure form, laboratory prepared mixtures and pharmaceutical dosage form. The first developed method was based on thin layer chromatographic (TLC) combined with densitometric determination of the separated spots. The separation was achieved using silica gel 60F254 TLC plates. The mobile phase used was chloroform: methanol (9.2:0.8, v/v) and UV detection at 240 nm. Good correlations were obtained between the integrated peak area of the studied analytes and their corresponding concentrations in different ranges. The second developed method was based on the high-performance liquid chromatography with ultraviolet detection, by which the proposed components were separated using Zorbax C 18 column using a mobile phase consisting of sodium acetate buffer (pH=4.5, adjusted with acetic acid): acetonitrile : triethylamine (50:50:0.5, by volume) maintaining the mobile phase flow rate at 1 mLmin -1 with UV detection at 260 nm. Different parameters affecting the suggested methods were optimized for maximum separation of the cited components. System suitability parameters of the two developed methods were also tested. Validation of the methods has been carried out according to USP requirements and ICH guidelines, accuracy, precision and repeatability were found to be within the acceptable limits. The results obtained by TLC-Densitometric and RP-HPLC methods were statistically compared with those obtained by the reported RP-HPLC method and no significant difference was found regarding both accuracy and precision.

Spectrophotometric Methods for Simultaneous Determination of Two Hypouricemic Drugs in their Combined Dosage Form

Four simple, precise and accurate spectrophotometric methods have been developed for simultaneous determination of Allopurinol (ALP) and Benzbromarone (BENZ) in their bulk powder and pharmaceutical dosage form. Method (I) is dual wavelength analysis, method (II) is Q-analysis (graphical absorbance ratio) method, method (III) is the mean centering of ratio spectrophotometric (MCR) method while method (IV) is the extended ratio subtraction method (EXRSM). In method (I) two wavelengths were selected for each drug in such a way that the difference in absorbance was zero for the second drug. At wavelengths 238.2 and 261.2 nm ALP had equal absorbance values; therefore, these two wavelengths have been used to determine BENZ; on a similar basis 253 and 274.4 nm were selected to determine ALP. Method (II) involves the formation of Q-absorbance equation using the respective absorptivity values at 245.8 nm (isoabsorptive point) and 250 nm (λmax of ALP). In method (III) the absorption spectra of both ALP and BENZ with different concentrations were recorded over 210-280 and 210-275 nm, respectively, divided by the spectrum of suitable divisor of both ALP and BENZ and then they obtained ratio spectra were mean centered. Method (IV) starts with the normal ratio subtraction method (RSM) for determination of ALP at its λmax (250 nm), while an extension of the already developed method has been established as a new approach for BENZ determination at its λmax (238 nm). Accuracy, precision and recovery studies of the developed methods have been carried out in order to confirm their accuracy. Specificity of the methods was also tested by their application for determination of different synthetic mixtures and they have been successfully used for drugs determination in their combined dosage form. Statistical comparison of the developed methods with the reported HPLC one showed no significant difference.

HPTLC and RP-HPLC methods for simultaneous determination of Paracetamol and Pamabrom in presence of their potential impurities.

Two chromatgraphic methods were developed for determination of Paracetamol (PCM) and Pamabrom (PAM) in presence of P-aminophenol (PAP) and Theophylline (THEO) as potential impurities of both drugs respectively. First method is HPTLC which depends on separation and quantitation of the studied drugs on aluminum plates pre-coated with silica gel 60 F₂₅₄ as a stationary phase using chloroform:methanol:ethyl acetate:glacial acetic acid (8:0.8:0.6:0.2, v/v/v/v) as mobile phase followed by densitometric measurement of the bands at 254 nm. Second method is RP-HPLC which comprises separation of the studied drugs on a Phenomenex C8 column by gradient elution using mobile phase consisting of sodium dihydrogen phosphate buffer (0.05 M): methanol:acetonitrile (85:10:5, v/v/v) at a flow rate of 1 mL/min for first 7.5 min and (70:20:10, v/v/v) at a flow rate of 1.5 mL/min for the next 5 min. The proposed methods were successfully applied for determination of the potential impurities of PCM and PAM after resolving them from the pure drugs. The developed methods have been validated and proved to meet the requirements delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. The validated methods were successfully applied for determination of the studied drugs in their pharmaceutical formulation. The results were statistically compared to those obtained by the reported RP-HPLC method where no significant difference was found; indicating the ability of proposed methods to be used for routine quality control analysis of these drugs.

Validated Chromatographic Methods for Simultaneous Determination of Amlodipine Besylate and Perindopril Arginine in Binary Mixtures and in Pharmaceutical Dosage Form

Two accurate, selective and precise chromatographic methods, namely TLC-densitometric method & RP-HPLC method & were developed and validated for the simultaneous determination of Amlodipine besylate and Perindopril Arginine in their binary mixtures. The developed TLC-densitometric method depends on separation and quantitation of the studied drugs on silica gel 60F254 TLC plates. Chloroform:methanol:deionized water:glacial acetic acid:triethylamine (10:7:5:0.3:0.2, by volume) was used as developing system and the separated bands were scanned at 208 nm. Linear relationship was obtained in the range 1-10 μg for both drugs. The developed RP-HPLC depends on quantitative chromatographic separation of the studied drugs on a C18 column using phosphate Buffer:acetonitrile (60:40, v/v), pH=4.6 as a mobile phase delivered at constant flow rate of 1 mL.min-1 with UV detection at 210 nm. Calibration curves for Amlodipine besylate and Perindopril Arginine were constructed over the concentration range of 1-50 μg.mL-1 for both drugs. The proposed methods were successfully applied for determination of the studied drugs in their bulk powder and in pharmaceutical formulations. The proposed methods were statistically compared to each other using student’s t test and F-test and no significant difference was found between them.