Two green and sensitive spectrofluorimetric approaches for determination of Ambroxol and guaifenesin in their single and combined pharmaceutical formulations

Ambroxol hydrochloride (AMX) and guaifenesin (GFN) are approved drugs utilized to treat coughs through their potent mucolytic and expectorant properties. Due to their massive, combined administration in many illnesses, there is a persistent need for their concurrent estimation in different pharmaceutical formulations. Two sensitive, environmentally friendly spectrofluorimetric methods were developed. AMX was determined using the first method (I) without interference from GFN. This method depends on the quenching of Erythrosine B (EB) native fluorescence at 552 nm after excitation at 527 nm due to the formation of a non-fluorescent AMX-EB ion-pair complex in Britton–Robinson buffer (BRB) solution pH (3.5). The concentration plot is linear over the 0.25–5.0 μg/mL range, with a mean percent found value of 99.74%. Method (II) depends on measuring the native fluorescence of aqueous GFN solution at two analytical wavelengths, either 300 or 600 nm, after excitation at 274 nm. Relative fluorescence intensity (RFI)–concentration plots are linear over the ranges of 0.02–0.5 and 0.1–2.0 μg/ml, with mean percent found at 99.96% and 99.91% at dual wavelengths, respectively. The proposed methods were successfully applied to assay both drugs in raw materials and different single and combined pharmaceutical formulations. These methods have been thoroughly validated following International Committee on Harmonisation (ICH) guidelines. National Environmental Methods Index, Analytical Eco-Scale, and Green Analytical Procedure Index were used to prove greenness, thereby enhancing their applicability. The proposed techniques provide straightforward, precise, and cost-effective solutions for routine formulation analysis in quality control laboratories.     

Second‐derivative synchronous spectrofluorimetric determination of nebivolol hydrochloride and amlodipine besylate in their combined dosage form

A rapid, simple, accurate and highly sensitive spectrofluorimetric method was developed for the simultaneous analysis of nebivolol hydrochloride (NEB) and amlodipine besylate (AML). The method was based on measuring the synchronous fluorescence intensity of the drugs at Δλ = 40 nm in methanol. Various experimental parameters affecting the synchronous fluorescence of the studied drugs were carefully studied and optimized. The calibration plots were rectilinear over concentration ranges of 0.05–1.5 µg/mL and 0.5–10 µg/mL for NEB and AML with limits of detection (LOD) of 0.010 and 0.051 µg/mL and limits of quantitation (LOQ) of 0.031 and 0.156, respectively. The peak amplitudes (²D) of the second derivative synchronous fluorimetry (SDSF) were estimated at 282 nm for NEB and at 393 nm for AML. Good linearity was obtained over the concentration ranges. The proposed method was successfully applied to the determination of the studied compounds in laboratory‐prepared mixtures, commercial single and laboratory‐prepared tablets. The results were in good agreement with those obtained using the comparison method. The mean percent recoveries were found to be 100.12 ± 0.77 and 99.91 ± 0.77 for NEB and AML, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

Study on the interaction between erythrosine B and the cardiac drug amiodarone using fluorescence,scattering, and absorbance spectra and their analytical application

In an acidic buffered solution, erythrosine B can react with amiodarone to form an association complex, which not only generates great enhancement in resonance Rayleigh scattering (RRS) spectrum of erythrosine B at 346.5 nm but also results in quenching of fluorescence spectra of erythrosine B at λ_emission = 550.4 nm/λ_excitation = 528.5 nm. In addition, the formed erythrosine B–amiodarone complex produces a new absorbance peak at 555 nm. The spectral characteristics of the RRS, absorbance, and fluorescence spectra, as well as the optimum analytical conditions, were studied and investigated. As a result, new spectroscopic methods were developed to determine amiodarone by utilizing erythrosine B as a probe. Moreover, the ICH guidelines were used to validate the developed RRS, photometric, and fluorimetric methods. The enhancements in the absorbance and the RRS intensity and the decrease in the fluorescence intensity of the used probe were proportional to the concentration of amiodarone in ranges of 2.5–20.0, 0.2–2.5, and 0.25–1.75 μg/mL, respectively. Furthermore, limit of detection values were 0.52 ng/mL for the spectrophotometric method, 0.051 μg/mL for the RRS method, and 0.075 μg/mL for the fluorimetric method. Moreover, with good recoveries, the developed spectroscopic procedures were applied to analyze amiodarone in its commercial tablets.     

Fluorimetric determination of proteins using 4‐chloro‐(2′‐hydroxylophenylazo)rhodanine–Ti(IV) complex as a spectral probe

A novel method for the determination of proteins was developed, based on the enhancement of fluorescence with 4‐chloro‐(2′‐hydroxylophenylazo)rhodanine–Ti(IV) [ClHARP–Ti(IV)] complex as a fluorescence probe. The excitation and emission wavelengths of the system were 335 nm and 376 nm, respectively. The presence of bis(2‐ethylhexyl)sulphosuccinate sodium salt (AOT) microemulsion greatly increased the sensitivity of the system. Under optimal conditions, four kinds of proteins, including bovine serum albumin (BSA), human serum albumin (HSA), egg albumin (Ova), and γ‐globin (γ‐G) were studied. The detection limits were 0.182 µg/mL for BSA, 0.0788 µg/mL for HSA, 0.216 µg/mL for Ova and 0.484 µg/mL for γ‐G. The linear ranges of the calibration were 0–12.0, 0–10.0, 0–18.0 and 0–18.0 µg/mL, respectively. The method possessed high sensitivity, good selectivity and was applied to the analysis of protein in milk powder and cornmeal with satisfactory results. Copyright © 2008 John Wiley & Sons, Ltd.     

Spectrofluorimetric method for the determination of sulpiride in pharmaceutical preparations and human plasma through derivatization with 2‐cyanoacetamide

A sensitive and accurate spectrofluorimetric method has been developed for the determination of sulpiride in pharmaceutical preparations and human plasma. The developed method is based on the derivatization reaction of 2‐cyanoacetamide with sulpiride in 30% ammonical solution. The fluorescent derivatized reaction product exhibited maximum fluorescence intensity at 379 nm after excitation at 330 nm. The optimum conditions for derivatization reactions were studied and the fluorescence intensity versus concentration plot was found to be linear over the concentration range 0.2–20.0 µg/mL with a correlation coefficient of 0.9985. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.82 and 2.73 ng/mL, respectively. The proposed method was validated according to ICH guidelines. The effects of common excipients and co‐administered drugs were also studied. The accuracy of the method was checked using the standard addition method and percent recoveries were found to be in the range of 99.00–101.25% for pharmaceutical preparations and 97.00–97.80% for spiked human plasma. The method was successfully applied to commercial formulations and the results obtained for the proposed method were compared with a high‐performance liquid chromatography reference method and statistically evaluated using the Student's t‐test for accuracy and the variance ratio F‐test for precision. A reaction pathway was also proposed. Copyright © 2012 John Wiley & Sons, Ltd.     

Eco-friendly synchronous fluorescence spectrofluorimetric method for simultaneous determination of montelukast sodium and fexofenadine hydrochloride in their antiallergic rhinitis fixed-dose combination tablets

An innovative, simple, accurate, sensitive, and eco-friendly synchronous fluorescence spectrofluorimetric method has been developed for the simultaneous analysis of montelukast sodium (MON) and fexofenadine hydrochloride (FEX). The method relies on measuring the relative synchronous fluorescence intensity of both drugs using Δλ of 60 nm in methanol at 405 nm for MON and 288 nm for FEX. The experimental parameters influencing the developed method were investigated and optimized. The method was linear over the ranges 0.1–2.0 and 2.0–20.0 μg/ml for MON and FEX, respectively. The limits of detection were 0.018 and 0.441 μg/ml, and the limits of quantitation were 0.055 and 1.336 μg/ml for MON and FEX, respectively. The developed method was applied successfully for the determination of the two drugs in their newly released fixed-dose combination prescribed for the treatment of allergic rhinitis. The mean per cent recoveries were found to be 100.680 ± 0.890 and 100.110 ± 0.940 for MON and FEX, respectively. Furthermore, the method was found to be eco-friendly green as was evaluated according to the Green Analytical Procedure Index tool guidelines and analytical eco-scale.     

A very simple high‐performance liquid chromatographic method with fluorescence detection for the determination of gemifloxacin in human breast milk

A high‐performance liquid chromatographic method with fluorescence detection was developed and validated for the determination of gemifloxacin in human breast milk. The proposed method allows the determination of gemifloxacin in breast milk samples without complex sample preparation. The samples were mixed with a mobile phase and filtered with a 0.45 µm polytetrafluoroethylene filter before analysis. Chromatographic separation was carried out on a C18 column (150 × 4.6 mm, 5 µm I.D.) using methanol:50 mM ortho‐phosphoric acid solution (40:60) as the mobile phase with a 1.0 mL/min flow rate. Quantitation was performed using fluorescence detection with an excitation wavelength at 272 nm and an emission wavelength at 395 nm. The linear range was found to be 0.1–2.5 µg/mL. The method was applied successfully for the determination of gemifloxacin in breast milk obtained from a breastfeeding mother after oral administration of a single tablet that included 320 mg gemifloxacin per gemifloxacin tablet. Copyright © 2015 John Wiley & Sons, Ltd.     

Validated spectrofluorimetric determination of two pharmaceutical antihypertensive mixtures containing amlodipine besylate together with either candesartan cilexetil or telmisartan

Amlodipine besylate (AML) is available in fixed‐dose combination tablets with either candesartan cilexetil (CAN) or telmisartan (TEL). This work describes a simple, selective and sensitive spectrofluorimetric method for analysis of AML/CAN and AML/TEL binary mixtures without prior separation. The method involves measurement of the native fluorescence of AML at excitation and emission wavelengths of 367 and 454 nm, respectively, in water without interference from either of the two drugs. By contrast, the intrinsic fluorescence of CAN was measured at excitation and emission wavelengths of 265 and 392 nm, respectively, in ethanol, while TEL was measured at 366 nm in 0.05 M sodium hydroxide solution using 294 nm as the excitation wavelength. The proposed spectrofluorimetric procedure was validated with respect to linearity, ranges, precision, accuracy, selectivity, robustness, detection and quantification limits. Regression analysis showed a good correlation between fluorescence intensity and concentration over the ranges 0.1–1.4, 0.025–0.25 and 0.0025–0.05 µg/mL for AML, CAN and TEL, respectively. Limits of detection were 0.034, 0.0063 and 0.0007 µg/mL for AML, CAN and TEL, respectively. The proposed method was successfully applied for the analysis of several synthetic binary mixtures of different ratios and laboratory‐prepared tablets with good recoveries, and no interference from common pharmaceutical additives was observed. Copyright © 2014 John Wiley & Sons, Ltd.     

Fluorimetric determination of febuxostat in dosage forms and in real human plasma via Förster resonance energy transfer

A rapid, simple, selective and precise fluorimetric method was developed and validated for determination of a selective xanthine oxidase inhibitor; febuxostat (FBX) in pharmaceutical formulations and in human plasma. The proposed method is based on quenching effect of FBX on the fluorescence intensity of terbium (Tb³⁺) through fluorescence resonance energy transfer (FRET) from Tb³⁺ to FBX. The formed complex was measured at λ_ex. 320 nm/λ_em. 490 nm against a reagent blank. Fluorescence intensity of Tb³⁺ was diminished when FBX was added. A linear relationship between the fluorescence quenching value of the formed complex and the concentration of FBX was investigated. The reaction conditions and the fluorescence spectral properties of the complex have been studied. The linearity range of the developed method was 1.0–16.0 μg/ml. The suggested method was applied successfully for the estimation of FBX in bulk powder, dosage forms and spiked plasma samples with excellent recoveries (96.79–98.89%). In addition, the developed method has been successfully applied for determination of FBX in real plasma samples collected from healthy volunteers with good recoveries (82.06–85.65%). All obtained results of the developed method were statistically analyzed and validated according to ICH (International Conference on Harmonization) guidelines.     

Micellar-emphasized simultaneous determination of ivabradine hydrochloride and felodipine using synchronous spectrofluorimetry

A sensitive and green micellar spectrofluorimetric approach was applied for the simultaneous estimation of ivabradine hydrochloride (IVB) and felodipine (FLD) in the ng/ml concentration range. The approach depended on measuring the first derivative synchronous peak amplitude (¹D) of both drugs at ∆λ = 60 nm in a Tween-80 micellar system. The method was rectilinear alongside the concentration ranges 0.02–0.4 μg/ml and 0.05–1.0 μg/ml at 269.5 nm and 378.5 nm for IVB and FLD, respectively. The proposed method was validated by following the International Council for Harmonization guidelines. The method was successfully applied without interference for laboratory-prepared synthetic mixtures, single pharmaceutical preparations, and within spiked biological fluids with acceptable percentage recoveries. A comparison of the performance of the suggested method with other methods, showed no discrepancy. The method’s ecofriendly property evaluated using three different tools, confirming an excellent green method.     

Spectrophotometric and spectrofluorimetric determination of indacaterol maleate in pure form and pharmaceutical preparations: application to content uniformity

Two simple, rapid, sensitive and precise spectrophotometric and spectrofluorimetric methods were developed for the determination of indacaterol maleate in bulk powder and capsules. Both methods were based on the direct measurement of the drug in methanol. In the spectrophotometric merthod (Method I) the absorbance was measured at 259 nm. The absorbance‐concentration plot was rectilinear over the range 1.0–10.0 µg mL^?1 with a lower detection limit (LOD) of 0.078 µg mL^?1 and lower quantification limit (LOQ) of 0.238 µg mL^?1. Meanwhile in the spectrofluorimetric method (Method II) the native fluorescence was measured at 358 nm after excitation at 258 nm. The fluorescence‐concentration plot was rectilinear over the range of 1.0–40.0 ng mL^?1 with an LOD of 0.075 ng mL^?1and an LOQ of 0.226 ng mL^?1. The proposed methods were successfully applied to the determination of indacaterol maleate in capsules with average percent recoveries ± RSD% of 99.94 ± 0.96 for Method I and 99.97 ± 0.81 for Method II. In addition, the proposed methods were extended to a content uniformity test according to the United States Pharmacopoeia (USP) guidelines and were accurate, precise for the capsules studied with acceptance value 3.98 for Method I and 2.616 for Method II. Copyright © 2015 John Wiley & Sons, Ltd.     

An eco‐friendly direct spectrofluorimetric method for the determination of irreversible tyrosine kinase inhibitors,neratinib and pelitinib: application to stability studies

A new rapid and simple stability‐indicating spectrofluorimetric method has been developed for the determination of two irreversible tyrosine kinase inhibitors (TKIs), neratinib (NER) and pelitinib (PEL). The method is based upon measurement of the native fluorescence intensity of both drugs at λ_ex 270 nm in aqueous borate buffer solutions (pH 10.5). The fluorescence intensity recorded at 545 nm (NER) and 465 nm (PEL) were rectilinear over the concentration range of 0.1–10 μg/mL for both drugs with a high correlation coefficient (r > 0.999). The proposed method provided low limits of detection and of quantitation of 0.07, 0.11 μg/mL (NER) and 0.02, 0.05 μg/mL (PEL), respectively. The method was successfully applied for the determination of NER and PEL in bulk powder. The proposed methods were fully validated as per the International Conference on Harmonisation (ICH) guidelines. The application of the method was extended to stability studies of both NER and PEL under different forced‐degradation conditions (acidic‐induced, base‐induced, oxidative, wet heat, and photolytic degradation). Moreover, the kinetics of the base‐induced and oxidative degradation of both drugs was investigated and the pseudo‐first‐order rate constants and half‐lives were estimated at different temperatures. Also, an Arrhenius plot was applied to predict the stability behaviour of the two drugs at room temperature. Copyright © 2016 John Wiley & Sons, Ltd.     

Simultaneous estimation of levodopa and carbidopa by RP‐HPLC using a fluorescence detector: its application to a pharmaceutical dosage form

A reverse‐phase high‐performance liquid chromatographic (RP‐HPLC) method was developed and validated for the simultaneous estimation of levodopa and carbidopa in bulk and pharmaceutical formulations. Chromatographic separation was achieved by using a C₁₈ reverse‐phase column and a mixture of an aqueous phase (10 mM potassium dihydrogen phosphate buffer, pH 4.0) and methanol (90:10 v/v) as the mobile phase. Quantitative analysis of levodopa and carbidopa was performed using a fluorescence detector at an excitation wavelength of 280 nm and an emission wavelength of 310 nm. The method was linear between 5 and 500 ng/mL for both levodopa and carbidopa. The detection limits for levodopa and carbidopa were 0.30 and 0.60 ng/mL, respectively, whereas the quantitation limit was 0.80 ng/mL for levodopa and 1.2 ng/mL for carbidopa. The method demonstrated good and consistent recoveries (99.63–100.80% for levodopa and 98.97–100.94% for carbidopa) with low interday and intraday relative standard deviation. The validated method was successfully applied to quantify levodopa and carbidopa simultaneously in a pharmaceutical formulation. The method was found to be precise, sensitive and accurate for the simultaneous determination levodopa and carbidopa in bulk and pharmaceutical formulations. Copyright © 2014 John Wiley & Sons, Ltd.     

Spectrofluorimetric determination of amisulpride and bumidazone in raw materials and tablets

A highly sensitive, simple and rapid spectrofluorimetric method was developed for the determination of amisulpride (AMS) and bumidazone (BUM) in tablet form. The proposed method is based on measuring the native fluorescence of the studied drugs in methanol at 360 and 344 nm after excitation at 276 and 232 nm for AMS and BUM, respectively. The fluorescence–concentration plots were rectilinear over the ranges of 5.0–60.0 ng/mL for AMS and 0.5–5.0 µg/mL for BUM. The lower detection limits were 0.70 ng/mL and 0.06 µg/mL, and the lower quantification limits were 2.0 ng/mL and 0.18 µg/mL for AMS and BUM, respectively. The method was successfully applied for the analysis of AMS and BUM in commercial tablets. Statistical evaluation and comparison of the data obtained using the proposed and comparison methods revealed good accuracy and precision for the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.     

Application of liquid chromatographic method with fluorescence detection for the determination of triclabendazole in tablets and biological fluids

A simple and rapid liquid chromatographic method was developed and validated for the determination of triclabendazole with high accuracy and precision within 6 min. Good chromatographic separation was achieved using a CLC Shim‐pack C₈ (250 × 4.6 mm, 5 µm particle size) using the mobile phase containing a mixture of 0.02 m phosphate buffer and methanol with a ratio of (20 : 80 v/v) at pH 4.0 was pumped at a flow rate of 1.2 mL/min with fluorescence detection for the first time at 338 nm after excitation at 298 nm. Losartan potassium was used as an internal standard. The method showed good linearity in the ranges of 0.05–2.0 µg/mL with limits of detection and quantification of 14.1 and 42.6 ng/mL, respectively. The suggested method was successfully applied for the analysis of triclabendazole in tablets. The high sensitivity of the method enabled the determination of the studied drug in spiked human plasma with mean percentage of recoveries of 99.79 ± 5.09. Statistical evaluation of the data was performed according to ICH Guidelines. Copyright © 2013 John Wiley & Sons, Ltd.     

Spectrofluorimetric determination of dopamine receptor antagonist LE 300 in mice plasma

A simple, rapid and highly sensitive spectrofluorimetric method was developed for determination of a novel type of dopamine receptor antagonist LE300 in mouse plasma. The method is based on measuring the native fluorescence of LE‐300 in methanol at 343 nm after excitation at 280 nm. The fluorescence concentration plot was rectilinear over the range of 3.5–100 ng/mL with a lower detection limit of 1.0 ng/mL and quantification limit of 3.5 ng/mL. The method was statistically validated for linearity, accuracy, precision and selectivity according to the International Conference on Harmonization guidelines. The accuracy and precision results was expressed as % recovery and relative standard deviation (RSD). The accuracy for LE‐300 was in the range 95.5–103.6% and RSD values were in the range of 0.21–1.55% of the theoretical value. The method was successfully applied to the analysis of LE‐300 in mice plasma. The results were compared statistically with those obtained by the reported method and were found to be in good agreement, which could be applied in a pharmacokinetic study. Copyright © 2015 John Wiley & Sons, Ltd.     

Spectrofluorimetric analysis of ethopabate in veterinary formulations with application to residue determination in chicken muscles and liver

Ethopabate is a veterinary drug used in the prophylaxis and treatment of coccidiosis in chickens. The presence of drug residues in edible tissues can be dangerous to human consumers. It may cause direct toxic effects, allergic reactions and increased bacterial resistance. A highly sensitive, simple and rapid spectrofluorimetric method was developed for the determination of ethopabate in its veterinary formulations. The proposed method is based on measuring the native fluorescence of ethopabate in water at 364 nm after excitation at 270 nm. The fluorescence–concentration plot was rectilinear over the range of 2–100 ng/mL, with a limit of detection of 2.9 ng/g and a limit of quantification of 9.8 ng/g for ethopabate. The method was successfully applied to the analysis of ethopabate in its commercial veterinary formulations and the results were in good agreement with those obtained with the reference method. The method was extended to the determination of ethopabate residues in chicken muscles and liver, and the results were satisfactory. The recoveries obtained were in the 108.36–113.42% range. No organic solvents are used in the procedure, so it can be considered a type of ‘green’ chemistry. Copyright © 2014 John Wiley & Sons, Ltd.     

Spectrofluorimetric analysis of gemifloxacin mesylate in pharmaceutical formulations

A simple, rapid and highly sensitive spectrofluorimetric method was developed for determination of gemifloxacin mesylate (GFX) in tablets. The method is based on measuring the native fluorescence of GFX in isopropanol at 400 nm after excitation at 272 nm. The fluorescence–concentration plot was rectilinear over the range of 0.01–0.50 µg/mL with a lower detection limit of 1.19 ng/mL and quantification limit of 3.6 ng/mL. The method was fully validated and successfully applied to the determination of GFX tablets with an average percentage recovery of 99.65 ± 0.532. The method was extended to the stability study of GFX. The drug was exposed to acidic, alkaline, oxidative and photolytic degradation according to International Conference on Harmonization guidelines. The rate of GFX degradation was found at its highest in acidic conditions, and in its lowest in the neutral one. However, it was stable under dry heat and photolytic degradation conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Validated spectrofluorimetric method for the determination of carbamazepine in pharmaceutical dosage forms after reaction with 4‐chloro‐7‐‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD‐Cl)

A sensitive and simple spectrofluorimetric method has been developed and validated for the determination of the anti‐epileptic drug carbamazepine (CBZ) in its dosage forms. The method was based on a nucleophilic substitution reaction of CBZ with 4‐chloro‐7‐nitrobenzo‐2‐ oxa‐1,3‐diazole (NBD‐Cl) in borate buffer (pH 9) to form a highly fluorescent derivative that was measured at 530 nm after excitation at 460 nm. Factors affecting the formation of the reaction product were studied and optimized, and the reaction mechanism was postulated. The fluorescence–concentration plot is rectilinear over the range of 0.6–8 µg/mL with limit of detection of 0.06 µg/mL and limit of quantitation of 0.19 µg/mL. The method was applied to the analysis of commercial tablets and the results were in good agreement with those obtained using the reference method. Validation of the analytical procedures was evaluated according to ICH guidelines. Copyright © 2015 John Wiley & Sons, Ltd.     

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. Copyright © 2014 John Wiley & Sons, Ltd.