Nariman A. El-Ragehy

Stability-indicating determination of meropenem in presence of its degradation product

Stability-indicative determination of meropenem (MERM) in the presence of its open-ring degradation product, the metabolite, is investigated. The degradation product has been isolated, via acid-degradation, characterized and confirmed. Selective quantification of MERM, singly in bulk form, pharmaceutical formulations and/or in the presence of its major degradate is demonstrated. The indication of stability has been undertaken under conditions likely to be expected at normal storage. Among the analytical techniques adopted for quantification are spectrophotometry [first-derivative ((1)D), first-derivative of ratio spectra ((1)DD) and bivariate analysis], as well as chromatography [coupled TLC-densitometry and HPLC].

Selective determination of ertapenem in the presence of its degradation product

Stability-indicative determination of ertapenem (ERTM) in the presence of its beta-lactam open-ring degradation product, which is also the metabolite, is investigated. The degradation product has been isolated, via acid-degradation, characterized and elucidated. Selective quantification of ERTM, singly in bulk form, pharmaceutical formulations and/or in the presence of its major degradant is demonstrated. The indication of stability has been undertaken under conditions likely to be expected at normal storage conditions. Among the spectrophotometric methods adopted for quantification are first derivative ((1)D), first derivative of ratio spectra ((1)DD) and bivariate analysis.

Novel potentiometric application for the determination of pantoprazole sodium and itopride hydrochloride in their pure and combined dosage form

Three sensitive and selective polyvinyl chloride (PVC) matrix membrane electrodes were developed and investigated. Sensor I was developed using tetraheptylammonium bromide (THB) as an anion exchanger with 2-nitrophenyl octyl ether (2-NPOE) as a plasticizer for the determination of the anionic drug pantoprazole sodium sesquihydrate (PAN). To determine the cationic drug itopride hydrochloride (ITH), two electrodes (sensors II and III) were developed using potassium tetrakis(4-chlorophenyl) borate (KTCPB) as a cation exchanger with dioctyl phthalate (DOP) as a plasticizer. Selective molecular recognition components, 2-hydroxypropyl-β-cyclodextrin (2-HP βCD) and 4-tert-butylcalix[8]arene (tBC8), were used as ionophores to improve the selectivity of sensors II and III, respectively. The proposed sensors had a linear dynamic range of 1×10(-5) to 1×10(-2) mol L(-1) with Nernstian slopes of -54.83±0.451, 56.90±0.300, and 51.03±1.909 mV/decade for sensors I, II and III, respectively. The Nernstian slopes were also estimated over the pH ranges of 11-13, 3.5-8 and 4-7 for the three sensors, respectively. The proposed sensors displayed useful analytical characteristics for the determination of PAN and ITH in bulk powder, in laboratory prepared mixtures and in combined dosage forms with clear discrimination from several ions, sugars and some common drug excipients. The method was validated according to ICH guidelines. Statistical comparison between the results from the proposed method and the results from the reference methods showed no significant difference regarding accuracy and precision.

SPECTROPHOTOMETRIC AND STABILITY INDICATING HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC DETERMINATION OF NORTRIPTYLINE HYDROCHLORIDE AND FLUPHENAZINE HYDROCHLORIDE

ABSTRACT Spectrophotometric and high performance liquid chromatographic procedures are described for determination of nortriptyline hydrochloride and fluphenazine hydrochloride. The first procedure is based on application of first derivative of ratio spectra (1DD) for quantitative determination of nortriptyline hydrochloride in presence of fluphenazine hydrochloride. Secondly, an accurate, sensitive and stability indicating method has been introduced for determination of nortriptyline hydrochloride and fluphenazine hydrochloride in both bulk powder and in dosage form. In the derivative ratio method, Beers law is obeyed in the concentration ranges of 8–32 µg mL−1 and 4–32 µg mL−1 of nortriptyline hydrochloride at wavelengths 271.4 and 284.2 nm, respectively. In high performance liquid chromatographic method, linear relationship in the range of 0.6–3.6 µg mL−1 and 1.2–4.2 µg mL−1 for nortriptyline hydrochloride and fluphenazine hydrochloride, respectively, was obtained. The mobile phase used was 0.05 M ammonium acetate : methanol : acetonitrile (4 : 1 : 5 v/v/v), and detection was done spectrophotometrically at 254 nm. Results were statistically analyzed and compared with those obtained by applying the British Pharmacopoeia (2000) method.

Simultaneous determination of olanzapine and fluoxetine hydrochloride in capsules by spectrophotometry, TLC-spectrodensitometry and HPLC

This paper describes sensitive, accurate and precise spectrophotometric, TLC-spectrodensitometric and high performance liquid chromatographic (HPLC) methods for simultaneous determination of olanzapine and fluoxetine HCl. Two spectrophotometric methods were developed, namely; first derivative (D1) and derivative ratio (DD1) methods. The TLC method employed aluminum TLC plates precoated with silica gel GF254 as the stationary phase and methanol:toluene:ammonia (7:3:0.1, by volume) as the mobile phase, where the chromatogram was scanned at 235 nm. The developed HPLC method used a reversed phase C18 column with isocratic elution. The mobile phase composed of phosphate buffer pH 4.0:acetonitrile:triethylamine (53:47:0.03, by volume) at flow rate of 1.0 mL min−1. Quantitation was achieved with UV detection at 235 nm. The methods were validated according to the International Conference on Harmonization (ICH) guidelines. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The developed methods were successfully applied for the determination of olanzapine and fluoxetine HCl in bulk powder and combined capsule dosage form.

Simultaneous determination of a binary mixture of pantoprazole sodium and itopride hydrochloride by four spectrophotometric methods

Four simple, sensitive, accurate and precise spectrophotometric methods were developed for the simultaneous determination of a binary mixture containing Pantoprazole Sodium Sesquihydrate (PAN) and Itopride Hydrochloride (ITH). Method (A) is the derivative ratio method ((1)DD), method (B) is the mean centering of ratio spectra method (MCR), method (C) is the ratio difference method (RD) and method (D) is the isoabsorptive point coupled with third derivative method ((3)D). Linear correlation was obtained in range 8-44 μg/mL for PAN by the four proposed methods, 8-40 μg/mL for ITH by methods A, B and C and 10-40 μg/mL for ITH by method D. The suggested methods were validated according to ICH guidelines. The obtained results were statistically compared with those obtained by the official and a reported method for PAN and ITH, respectively, showing no significant difference with respect to accuracy and precision.

Simultaneous Determination of Aspirin, Dipyridamole and Two of Their Related Impurities in Capsules by Validated TLC-Densitometric and HPLC Methods

Aspirin (ASP) and dipyridamole (DIP) are widely used as a combination in pharmaceutical formulations for treatment of strokes. Many of these formulations are containing tartaric acid as an excipient (in DIP pellets formulation for sustained release), which increases the probability of formation of dipyridamole tartaric acid ester impurity (DIP-I). On the other hand, salicylic acid (SAL) is considered to be one of the synthesis impurities and a degradation product of ASP. In this work, two chromatographic methods, namely, TLC-densitometry and HPLC, have been established and validated for simultaneous determination of ASP, DIP, SAL and DIP-I. Good separation was achieved by using silica gel as stationary phase and toluene-methanol-ethyl acetate (2:3:5, by volume) as mobile phase in the case of TLC-densitometry and Zorbax ODS column with mobile phase consisting of phosphate buffer (pH 3.3)-acetonitrile-triethylamine (40:60:0.03, by volume) for HPLC. Influence of different organic solvents in mobile phase composition has been studied to optimize the separation efficiency in TLC densitometry. Moreover, factors affecting the efficiency of HPLC, like pH of the buffer used, organic solvent ratio in the mobile phase and flow rate, have been carefully studied using one variable at a time approach. Finally, the proposed methods were validated as per ICH guidelines.

Stability-indicating spectrophotometric methods for determination of the anticoagulant drug apixaban in the presence of its hydrolytic degradation product

Apixaban (a novel anticoagulant agent) was subjected to a stress stability study including acid, alkali, oxidative, photolytic, and thermal degradation. The drug was found to be only liable to acidic and alkaline hydrolysis. The degradation product was then isolated and identified by IR and GC-mass spectrometry. Four spectrophotometric methods, namely; first derivative (D(1)), derivative ratio (DR), ratio difference (RD) and mean centering of ratio spectra (MCR), have been suggested for the determination of apixaban in presence of its hydrolytic degradation product. The proposed methods do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the degradation product with the drug. The developed methods were successfully applied for the determination of apixaban in bulk powder and its tablet dosage form.

Stability-Indicating Chromatographic Methods for the Determination of Sertindole

In this work, two chromatographic methods have been developed and validated for the determination of sertindole (an antipsychotic agent) in the presence of its oxidative degradation product. Sertindole was subjected to stress stability studies, including acid, alkali, oxidative, photolytic and thermal degradation. The chromatographic methods included the use of thin-layer chromatography (TLC-densitometry) and high-performance liquid chromatography (HPLC). The TLC method employed aluminum TLC plates precoated with silica gel G.F254 as the stationary phase and methanol-ethyl acetate-33% ammonia (1:9:0.1, by volume) as the mobile phase, and the chromatograms were scanned at 227 nm. The developed HPLC method used a reversed-phase C18 column with isocratic elution. The mobile phase was composed of phosphate buffer pH 3.0-acetonitrile-triethylamine (45:55:0.03, by volume) and run at a flow rate of 1.0 mL/min. Quantitation was achieved with ultraviolet detection at 256 nm. The linearity ranges were found to be 2-14 µg/band and 5-200 µg/mL for TLC and HPLC, respectively. The developed methods were validated according to the International Conference on Harmonization guidelines and were applied for bulk powder and dosage forms.

Validated Chromatographic Methods for the Simultaneous Determination of Sulfacetamide Sodium and Prednisolone Acetate in their Ophthalmic Suspension

Two specific, sensitive, rapid and accurate chromatographic methods have been developed, optimized and validated for the simultaneous determination of sulfacetamide sodium and prednisolone acetate in pure forms and in their binary mixture. The first method is an isocratic Reversed phase-high performance liquid chromatography method where a rapid separation was achieved on a Zorbax ODS column using a green mobile phase of methanol: water (80:20, v/v) and pH adjusted to 5.0 ± 0.2 with orthophosphoric acid. The retention times (tR) were 2.21 and 3.64 min for sulfacetamide sodium and prednisolone acetate, respectively. The separated peaks were detected at 254 nm. The second method is a thin layer chromatography-densitometric method where the two drugs were separated on silica gel plates using a simple mobile phase of chloroform: methanol (90:10, v/v) and scanning of the separated bands was at 254 nm. The retardation factors (Rf) values were 0.37 and 0.64 for sulfacetamide sodium and prednisolone acetate, respectively. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied to determine both drugs in their pure forms, laboratory prepared mixtures and dosage form. The obtained results were statistically compared to the official method where no significant difference was obtained with respect to both accuracy and precision.