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Two Eco-friendly methods based on chromatographic separation were developed for simultaneous assay of Tamsulosin HCl and Deflazacort in their binary mixture. Green mobile phase which consists of mixture of ethanol and dilute acetic acid was employed for both developed methods. The first method was reversed phase high performance liquid chromatography (RP-HPLC) with a photodiode array (DAD) detection for quantification of both drugs at wavelengths of 225 and 245 nm over a linearity range of 0.20–100 and 0.50–200 μg mL−1 for Tamsulosin HCl and Deflazacort, respectively. The second method was high performance thin layer chromatography (HPTLC) for separation and detection of the drugs by densitometry at 225 nm in the range of 0.30–4.0 and 0.70–5.0 μg band−1 of Tamsulosin HCl and Deflazacort, respectively. The proposed methods were validated to comply with ICH guidelines. Regarding the high liability of Deflazacort to be degraded to its active metabolite: 21-Hydroxy Deflazacort, the suggested methods were assessed for their applicability to determine the two drugs in the presence of 21-Hydroxy Deflazacort and evaluated based on chromatographic system suitability parameters. Application of the proposed methods was performed for determination of Tamsulosin HCl and Deflazacort in their combined tablet dosage form besides monitoring its in-vitro dissolution patterns by the RP-HPLC method. The greenness of the suggested methods was evaluated using the Analytical Eco-scale and compared with the other official or reported methods for determination of cited drugs.

Background Stability indicating determination of pharmaceuticals is crucial, especially for drugs which have few published official analytical methods. Silodosin (SLD) is an FDA approved α1A-adrenoceptor blocker. Objective Efficient analytical methods were suggested, based on different instrumental techniques for quantification of SLD, besides conducting kinetic investigation of its degradation. Methods The first method is based on Reversed Phase High Performance Liquid Chromatography with Photodiode Array Detector (RP-HPLC-PDAD). Detection is done at wavelength 225 nm. The second method is focused on using High Performance Thin Layer Chromatography (HPTLC) and eluting the drug by solvent mixture followed by scanning at wavelength 270 nm. The third method depends on the First Derivative Synchronous Fluorescence Spectroscopy (1DSFS) for analysis of solutions of SLD and its acid and oxidative induced degradation products at Δλ = 90 nm, then determining the first derivative of the spectra and measuring peak amplitudes at 360 nm. Results Acceptable linearities were found in the concentration range of 0.50–90 μg/mL, 0.10–3.0 μg/band, and 0.05–0.50 µg/mL, for RP-HPLC-PDAD, HPTLC, and spectrofluorimetric methods, respectively. Conclusion Statistical analysis showed no significant difference between the suggested and the reported method. In monitoring the kinetics of SLD degradation, the order of reactions was determined and effects of degrading agent concentration and temperature on reaction rate were studied. Highlights Three analytical methods were developed for the determination of SLD based on RP-HPLC-PDAD, HPTLC, and 1DSFS in bulk and capsule dosage form. In addition, kinetic investigation of SLD degradation was performed using the developed RP-HPLC-PDAD method.

Beta 2 agonists are well known for their use in the treatment of asthma and COPD however in the last few years new indications of beta 2 agonist appeared like reduction of local fats and treatment of preterm labour which required the formulation of new dosage forms and administration strategies. The new developments require accurate, economic and feasible methods the determination of these drugs to facilitate testing the newly introduced dosage forms and to study the pharmacokinetics and pharmacodynamics regarding the modern uses. In this study two rapid, sensitive and economic colorimetric methods for the determination of salmeterol xinafoate and salbutamol in pharmaceutical dosage forms and spiked plasma were developed and validated. The developed methods depends on the optimized reaction of the studied drugs with two charge transfer reagents, 2,3-dochloro-5,6-dicyano-1,4-benzoquonone (DDQ) and chloranilic acid (CA) to produce coloured complexes measured at 460 and 529 nm for DDQ and CA respectively. The developed methods showed high accuracy of 99.52 ± 1.108, 101.03 ± 0.389, 100.04 ± 1.520 and 100.3 ± 0.951 for salmetrol xinafoate and salbutamol with DDQ and CA respectively. The proposed methods were successfully used for the determination of the studied drugs in their dosage forms and spiked plasma with high accuracy and precision and the results were compared to reported methods.

Two precise and selective stability-indicating RP-LC methods have been developed and validated for simultaneous determination of metolazone in its binary mixture with losartan potassium (method 1) and spironolactone (method 2) in the presence of their degradation products. For method 1, the chromatographic separation was achieved on Kromasil C18 column, the mobile phase consisted of a mixture of 0.1% ortho-phosphoric acid in acetonitrile and 0.1% ortho-phosphoric acid in water (28:72, v/v) pumped at flow rate 2 mL/min and UV detection at 235 nm. Linearity was determined over the concentration range of 2–16µg/mL for metolazone and 40–320µg/mL for losartan potassium. For method 2, chromatographic separation of metolazone and spironolactone was achieved on a Symmetry C8 column using a mobile phase that consisted of acetonitrile, methanol, and 0.1% ortho-phosphoric in water in gradient mode pumped at a flow rate 1.5 mL/min with programed wavelength detection. Linearity was determined over the concentration range of 2–16µg/mL for metolazone and 20–160µg/mL for spironolactone. The suggested methods were proved to be highly selective, precise and accurate for simultaneous determination of the cited drugs in their combined pharmaceutical dosage form in the presence of their degradation products. The proposed methods were validated in compliance with ICH guidelines.HighlightsSynchronized determination of metolazone and co-formulated drugs in presence of their degradation products.Act as a method for screening of metolazone and co-formulated drugs in quality control laboratories.Validation of suggested methods according to ICH guidelines.The pathway of degradation of metolazone under different stress conditions was proposed. Synchronized determination of metolazone and co-formulated drugs in presence of their degradation products. Act as a method for screening of metolazone and co-formulated drugs in quality control laboratories. Validation of suggested methods according to ICH guidelines. The pathway of degradation of metolazone under different stress conditions was proposed.

Background Extraction is the leading critical stage in the analysis of nutraceuticals. Ginkgo biloba (GB) has gained interest because of its therapeutic usages. Objectives The aim was to develop four cost-effective extraction techniques for the extraction of quercetin from GB in a sachet containing a mixture of nutraceuticals. These techniques are solid-phase extraction (SPE), liquid–liquid extraction, inverted dispersive liquid–liquid microextraction, and the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. Method Direct spectrophotometry was used to monitor the recovery of the standard quercetin throughout the optimization steps. The HPLC–UV method of analysis was optimized to quantify the yields from the extracts present in the complicated contents of the sachets. The present study was assessed by analytical Eco-Scale assessment (ESA) and the National Environmental Method Index (NEMI) for greenness in comparison with the literature. Results SPE showed the best cleanup outcomes. ESA and NEMI showed an adequate greenness of the proposed extraction protocol. Conclusions Quercetin (marker for GB) extraction from market nutraceutical sachets is considered an exemplar for analysis in the QC of nutraceuticals. Regarding the greenness results, the proposed method of extraction is better even with adequate greenness as the extraction was a one-step process, in comparison with multistep processes of previously published protocols. Accordingly, it is recommended for use in routine extraction and analysis of such nutraceuticals. Highlights Four extraction protocols have been developed. For GB ternary-mixture sachets, proper recovery was obtained using C18 SPE. The assessment of greenness of the proposed protocol guaranteed the superiority of the presented method. Safer sorbents and chemicals are favored for use in routine extraction of nutraceuticals.

In a prospective randomized blind study, we investigated the effects of adding transdermal nitroglycerine for lidocaine and neostigmine for intravenous regional anesthesia in adult patients undergoing hand surgery. Patients and Methods Sixty patients (ASA grade I, aged 20-60 years) of both sexes were enrolled. The patients were randomly allocated to receive either 40ml of 0.5% lidocaine plus a transdermal placebo patch (control group n=15), 40ml of 0.5% lidocaine with 0.5mg of neostigmine plus a transdermal placebo patch (Neostigmine group, n=15), 40ml of 0.8% lidocaine plus a transdermal nitroglycerine patch (Nitroglycerine group, n=15) or 40ml of 0.5% lidocaine with 0.5mg of neostigmine plus a transdermal nitroglycerine patch (Neostigmine - Nitroglycerine group, n=15). All routine hemodynamic parameters and O2 saturation were monitored, surgical time, sensory and motor block onset times, sensory and motor block recovery times and time to first analgesic requirement were measured. Operative conditions and quality of anesthesia were also recorded. Results Sensory and motor block onset times were shorter in the neostigmine – nitroglycerine group compared with all other groups (p

Two accurate, selective, and precise chromatographic methods, namely TLC-densitometric and reversed-phase (RP)-HPLC, were developed and validated for the simultaneous determination of nifuroxazide (NIF) and its four synthesized impurities, which are also reported to be its related substances in the range of 10-100 μg/band and 10-100 μg/mL for NIF in the TLC and RP-HPLC methods, respectively. The developed TLC-densitometric method depended on the separation and quantitation of the studied components on silica gel 60 F254 TLC plates. Ethyl acetate-acetone-methanol-ammonia (85 + 25 + 5 + 0.5, v/v/v/v) was used as the developing system, and the separated bands were UV-scanned at 230 nm. On the other hand, the developed RP-HPLC method depended on chromatographic separation using a C8 column at 25°C and an aqueous solution of 0.1% sodium lauryl sulfate-acetonitrile as the mobile phase delivered according to the gradient elution program. Factors affecting the developed methods were studied and optimized. Also, method validation was carried out according to International Conference on Harmonization guidelines. The proposed methods were successfully applied for the determination of the studied drug in its bulk powder and in its pharmaceutical formulation. The developed methods showed no significant difference when compared with the reported RP-HPLC one. Their advantage is being the first stability-indicating methods for NIF and its genotoxic impurities.

Background Four rapid, accurate, and validated stability-indicating spectrophotometric methods have been described in the present work for the analysis of trimebutine maleate (TM) in existence of its degradation products in its authentic form and in pharmaceutical formulations excluding any separation steps. Results These methods were a dual-wavelength (DW) method which allows the determination of TM in existence of its degradation products at 243 nm and 269 nm, second derivative (D2) method measured at peak amplitude at 268 nm, ratio difference (RD) method at 242 nm and 278 nm, and constant center coupled with spectrum subtraction (CC-SS) method at 242 nm and 278 nm versus 278 nm. By applying the suggested methods, TM could be quantified in the range of 5.0–60.0 μg/mL with percentage recoveries 99.97 ± 0.40, 100.36 ± 0.58, 99.90 ± 0.42, and 100.15 ± 0.45 for DW, D2, RD, and CC-SS methods, respectively. International Conference on Harmonization guidelines were followed for validation of the described methods, and the application of laboratory-prepared mixtures along with different pharmaceutical drugs including the target drug showed favorable results without any contribution from additives. Conclusions Statistical comparison was used to compare the proposed and official methods, and satisfactory results for both accuracy and precision were obtained. The results confirm the applicability of the suggested methods for the determination of TM in quality control laboratories.

Direct analytical methods offer an excellent tool for rapid determination of pharmaceuticals without deviation from the green analytical chemistry principles. In this work, a potentiometric ion selective electrode (ISE) method for the selective determination of the α1A-adrenoceptor blocker, Tamsulosin HCl was developed, optimized and assessed for greenness. Six different PVC-membrane sensors were fabricated using 2-nitrophenyl octyl ether (NPOE) as a plasticizer. Three ion exchangers were used, namely sodium tetraphenyl borate (Na.TPB), sodium tetrakis- [3,5-bis (trifluoro- methyl) phenyl] borate (Na.Tetrakis) and ammonium reineckate (Amm. RK) in exchange with the two ionophores, 4-tert-Butylcalix [8] arene (Calix.) and 2-hydroxypropyl-β-cyclodextrin (β-CD). The electrochemical responses of all sensors were studied and recorded. The sensor which consisted of sodium tetraphenyl borate as ion exchanger and 4-tert-Butylcalix [8] arene as ionophore was selected for application to analysis of Tamsulosin HCl in dosage form and human urine. The electrochemical performance characteristics of the electrode were validated as per IUPAC recommendations. Analytical Eco Scale assessment was used for evaluation of the greenness of the method and compared with the USP official method for the determination of Tamsulosin HCl.

In this work application of a recently developed progressive resolution technique and the well-established successive resolution techniques either separately or in combination for the analysis of t...

Simple, cost-effective, safe, accurate, precise and environmentally friendly spectro-photometric methods were developed and validated for the quantitative determination of valaciclovir (VAL) in the presence of its related impurity in bulk powder and in its pharmaceutical preparation. This related impurity namely guanine (GUA) is the potential and synthesis impurity of VAL. The spectra of VAL and GUA show the same geometrical features with different absorptivities, so their resolution is very challengeable. A Comparative study was conducted for the results of the conventional methods namely, dual wavelength (DW), first derivative of ratio spectra (1DD) and mean centering of ratio spectra (MCR) versus the recently developed methods namely, induced dual wavelength (IDW), ratio difference (RD) and constant center (CC). The optimized methods allow the estimation of VAL in the concentration range 5-50 μg/mL. The methods were validated as per ICH guidelines and the specificity was assessed by analyzing s...

Two robust and selective stability-indicating chromatographic methods were developed and validated for the determination of metolazone in drug substance and pharmaceutical dosage form in the presence of its degradation products. The HPLC method employed a Kromasil C18 (250 × 4.6,5 μm) column and a mobile phase of acetonitrile: 0.2% orthophosphoric acid (32:68 v/v) at a flow rate 2 mL/min and detection at 238 nm. The separation was performed in HPLC isocratic mode. The robustness of the suggested method was assessed using the Plackett–Burman design, parameters affecting system suitability were established and non-significant intervals for the significant parameters were considered. The HPTLC method employed Nano-SIL-20 UV254 HPTLC plates as adsorbent, ethyl acetate: toluene: acetic acid solution (4:4:0.5, v/v/v), as a developing solvent system and densitometric detection at 238 nm. Metolazone was exposed to different stress conditions, including acid and alkaline hydrolysis and oxidative and photolytic degradation. The main degradation products obtained have been characterized and interpreted based on LC-MS. The linearity of the suggested methods was proved in the concentration range of 20–75 μg/mL for the HPLC method and 100–900 ng/spot for the HPTLC method. The suggested methods were validated according to international conference on harmonization guidelines. These methods were successfully dedicated for the estimation of metolazone in drug substance and pharmaceutical dosage form in the presence of its degradation products. The results of the suggested methods were evaluated and compared statistically with results obtained by an official method without finding any significant difference.

Aims: A simple TLC Spectrodensitometric method was developed for analysis of Orphenadrine Citrate (OR), Caffeine (CAF) and Aspirin (ASP) either in pure form or in their pharmaceutical preparations. Study Design: Validation study. Methodology: In this method, The three drugs were separated on silica gel plate using ethyl acetate: acetone: methanol: triethylamine (6:3:1:0.2, by Volume) as mobile phase at room temperature. Many experimental parameters such as band size, slit width, different developing mobile phases and scanning wavelengths were examined and the optimum conditions were selected. The obtained bands were then scanned at 220 nm. The three drugs were adequately resolved with the R­­f values of ASP (Rf = 0.08 ± 0.02), CAF (Rf = 0.55 ± 0.02) and OR (Rf = 0.35 ± 0.02). Validation parameters of the developed method were studied like linearity, accuracy, precision, and specificity. Results: Linearity of the proposed method was found to be in the concentration ranges 0.4-2 μg/band for ASP, 0.4-2 μg/band for CAF and 0.3-3 μg/band for OR. Conclusion: The suggested method was effectively used for analysis of ASP, CAF and OR in pure form and in their medicinal formulations. The method is proved to be specific, accurate and selective.

Avanafil (AVN) was recently co-formulated with dapoxetine HCl (DAP) for treatment of erectile dysfunction and premature ejaculation. Sensitive and simple reversed-phase (RP) high-performance liquid chromatographic method (HPLC) was developed and validated for their simultaneous determination using tadalafil (TAD) as an internal standard. Isocratic separation was achieved within run time of only 7.0 min on Eclipse C18 column (150 mm × 4.6 mm, 5 µm particle size) using a mobile phase composed of acetonitrile: 0.15% triethylamine (40:60, v/v) at pH = 4.0 adjusted with o-phosphoric acid. The analysis was performed at a flow rate of 1.0 mL/min with fluorescence detection at 236/370 nm for AVN, 236/410 nm for DAP, and 236/330 for TAD using time programming. The analytes were determined by their native fluorescence and the response was linear over concentration ranges of 0.05–40 and 0.01–30 µg/mL for AVN and DAP, respectively, with limits of detection of 0.043 and 0.007 µg/mL in a respective order. The developed...

This work is concerned with development and validation of three simple, specific, accurate and precise spectrophotometric methods for determination of flumethasone pivalate (FP) and clioquinol (CL) in their binary mixture and ear drops. Method A is a ratio subtraction spectrophotometric one (RSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is a mean center spectrophotometric one (MCR). The calibration curves are linear over the concentration range of 3–45 μg/mL for FP, and 2–25 μg/mL for CL. The specificity of the developed methods was assessed by analyzing different laboratory prepared mixtures of the FP and CL. The three methods were validated as per ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits.

Five simple, rapid, accurate, and precise spectrophotometric methods are developed for the determination of Silodosin (SLD) in the presence of its acid induced and oxidative induced degradation products. Method A is based on dual wavelength (DW) method; two wavelengths are selected at which the absorbance of the oxidative induced degradation product is the same, so wavelengths 352 and 377 nm are used to determine SLD in the presence of its oxidative induced degradation product. Method B depends on induced dual wavelength theory (IDW), which is based on selecting two wavelengths on the zero-order spectrum of SLD where the difference in absorbance between them for the spectrum of acid induced degradation products is not equal to zero so through multiplying by the equality factor, the absorption difference is made to be zero for the acid induced degradation product while it is still significant for SLD. Method C is first derivative (1D) spectrophotometry of SLD and its degradation products. Peak amplitudes are measured at 317 and 357 nm. Method D is ratio difference spectrophotometry (RD) where the drug is determined by the difference in amplitude between two selected wavelengths, at 350 and 277 nm for the ratio spectrum of SLD and its acid induced degradation products while for the ratio spectrum of SLD and its oxidative induced degradation products the difference in amplitude is measured at 345 and 292 nm. Method E depends on measuring peak amplitudes of the first derivative of the ratio (1DD) where peak amplitudes are measured at 330 nm in the presence of the acid induced degradation product and measured by peak to peak technique at 326 and 369 nm in the presence of the oxidative induced degradation product. The proposed methods are validated according to ICH recommendations. The calibration curves for all the proposed methods are linear over a concentration range of 5–70 μg/mL. The selectivity of the proposed methods was tested using different laboratory prepared mixtures of SLD with either its acid induced or oxidative induced degradation products showing specificity of SLD with accepted recovery values. The proposed methods have been successfully applied to the analysis of SLD in pharmaceutical dosage forms without interference from additives.

Two liquid chromatographic methods were developed and validated. Simple and sensitive thin-layer chromatography (TLC)-densitometric and high-performance liquid chromatographic (HPLC) methods were used for the simultaneous determination of flumethasone pivalate (FP), flumethasone pivalate related substance and impurity, flumethasone (FL), and clioquinol (CL). The proposed TLC-densitometric method has been developed using silica gel plates 60 F254 as a stationary phase with benzene-hexane-acetone-formic acid (5:4:2:0.13, by volume) as a developing system followed by densitometric measurements at 235 nm. The studied components were quantified in the range of 0.3–4, 0.3–3, and 1.5–5 μg band−1, respectively. For HPLC method, chromatographic separation was achieved within 11 min with the required peak symmetry, accuracy, and precision on ODS column using acetonitrile-water (70:30, v/v) as the mobile phase at a flow rate of 1 mL min−1 with ultraviolet (UV) detection at 235 nm. The calibration plots were linear o...

In this paper, we propose an efficient spectral collocation algorithm to solve numerically wave type equations subject to initial, boundary and non-local conservation conditions. The shifted Jacobi pseudospectral approximation is investigated for the discretization of the spatial variable of such equations. It possesses spectral accuracy in the spatial variable. The shifted Jacobi-Gauss-Lobatto (SJ-GL) quadrature rule is established for treating the non-local conservation conditions, and then the problem with its initial and non-local boundary conditions are reduced to a system of second-order ordinary differential equations in temporal variable. This system is solved by two-stage forth-order A-stable implicit RK scheme. Five numerical examples with comparisons are given. The computational results demonstrate that the proposed algorithm is more accurate than finite difference method, method of lines and spline collocation approach

Spectrophotometric and TLC-spectrodensitometric methods were developed and validated for the simultaneous determination of beclomethasone dipropionate (BEC) and salbutamol (SAL). The spectrophotometric methods include dual wavelength, ratio difference, constant center coupled with a novel method namely, spectrum subtraction and mean centering with mean percentage recoveries and RSD 99.72±1.07 and 99.70±1.12, 100.25±1.12 and 99.89±1.12, 99.66±1.85 and 99.19±1.32, 100.74±1.26 and 101.06±0.90 for BEC and SAL respectively. The TLC-spectrodensitometric method was based on separation of both drugs on TLC aluminum plates of silica gel 60 F254, using benzene: methanol: triethylamine (10:1.5:0.5 v/v/v) as a mobile phase, followed by densitometric measurements of their bands at 230 nm. The mean percentage recoveries and RSD were 99.07±1.25 and 101.35±1.50 for BEC and SAL respectively. The proposed methods were validated according to ICH guidelines and were applied for the simultaneous analysis of the cited drugs in synthetic mixtures and pharmaceutical preparation. The methods were found to be rapid, specific, precise and accurate and can be successfully applied for the routine analysis of BEC and SAL in their pharmaceutical formulation with no need for prior separation. The results obtained were statistically compared to each other and to that of the reported HPLC method. The statistical comparison showed that there is no significant difference regarding both accuracy and precision.

Aims: A simple RP-TLC Spectrodensitometric method was developed for determination of Hyoscine N-Butyl Bromide (HBB) and Paracetamol (PAR) either in bulk powder or in their pharmaceutical preparation. Study Design: Validation study. Methodology: In this method, HBB and PAR were separated on RP-18 W/ UV254 TLC plates using developing mobile phase consisting of methanol: citrate buffer (pH=1.5): triflouroacetic acid (70:30:0.1, by volume) at room temperature. Experimental conditions such as band size, slit width, different developing systems and scanning wavelength were carefully studied and the optimum conditions were selected. The obtained bands were then scanned at 210 nm. The two drugs were satisfactorily resolved with RF 0.60 ± 0.02 for HBB and 0.81 ± 0.02 for PAR. The validation of spectrodensitometric method was done regarding linearity, accuracy, precision, and specificity. Results: Linearity of the proposed methods was evaluated and it was found to lie within the concentration range of 2.0-12.0 µg.band-1 for HBB and 2.0-14.0 µg.band-1 for PAR. Conclusion: The proposed method was successfully applied for determination of HBB and PAR in pure form and in their different pharmaceutical formulations. The method proved to be specific, accurate and selective.

New accurate, selective, sensitive and precise methods were developed and validated for determination of paracetamol and diphenhydramine hydrochloride in the presence of P-amino phenol, the hydrolytic degradate and the most potential impurity of paracetamol and the N oxide degradation product of diphenhydramine in bulk form and in pharmaceutical formulation.Method A uses double divisor second derivative of ratio spectrophotometric technique, at 304nm for paracetamol and 256.4nm for diphenhydramine hydrochloride. Method B utilizes Principle Component Regression (PCR) and Partial Least Squares (PLS) chemometric techniques for quantification of the four components using a UV spectrum range of 210-350 nm. The proposed methods were successfully applied to the analysis of the mentioned drugs either in bulk powder or in pharmaceutical formulation without interference from other dosage form additives, and the results were statistically compared with the pharmacopoeial 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.

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.

Four sensitive, selective and precise stability indicating methods for the determination of isopropamide iodide (ISO) and trifluoperazine hydrochloride (TPZ) in their binary mixture and in presence of trifluoperazine oxidative degradate (OXD). Method A is a derivative spectrophotometric one, where ISO was determined by first derivative (D(1)) at 226.4 nm while TPZ was determined by second derivative (D(2)) at 270.2 nm. Method B is the first derivative of the ratio spectra (DD(1)) spectrophotometric method, ISO can be determined by measuring the peak amplitude at 227.4 nm using 5 microg mL(-1) of OXD as a divisor, while TPZ can be determined by measuring the peak amplitude at 249.2 and 261.4 nm using 15 microg mL(-1) of ISO as a divisor. Method C is the isoabsorptive spectrophotometric method. This method allows determination of ISO and TPZ in their binary mixture by measuring total concentration of ISO and TPZ at their isoabsorptive point at lambda(229.8) nm (Aiso1) while TPZ concentration alone can be determined at lambda(max) 311.2 nm, then ISO concentration can be determined by subtraction. On the same basis TPZ can be determined in presence of ISO and OXD, where OXD concentration alone was determined by measuring the peak amplitude at lambda(281.6) and lambda(309.4) nm while total concentration of TPZ and OXD was determined at their isoabsorptive points at (Aiso2 = 270.2 nm), (Aiso3 = 310.6 nm) and (Aiso4 = 331.8 nm) then TPZ concentration was determined by subtraction. Method D is the multivariate calibration techniques [the classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS)], using the information contained in the absorption spectra of ISO, TPZ and OXD mixtures. The selectivity of the proposed methods was checked using laboratory prepared mixtures. The proposed methods have been successfully applied to the analysis of ISO and TPZ in pharmaceutical dosage form without interference from other dosage form additives and the results were statistically compared with the reported method.

Simple, accurate, sensitive and validated UV spectrophotometric, chemometric and HPTLC-densitometric methods were developed for determination of oxybutynin hydrochloride (OX) in presence of its degradation product and additives in its pharmaceutical formulations. Method A is the first derivative of ratio spectra (DD(1)) which allows the determination of OX in presence of its degradate in pure form and tablets by measuring the peaks amplitude at 216 nm. Method B and C are principal component regression (PCR) and partial least-squares (PLS) for determination of OX in presence of its degradate in pure form, tablets and syrup. While, the developed high performance thin layer chromatography HPTLC-densitometric method was based on the separation of OX from its degradation product, methylparaben and propylparaben followed by densitometric measurement at 220 nm which allows the determination of OX in pure form, tablets and syrup. The separation was achieved using HPTLC silica gel F(254) plates and chloroform:methanol:ammonia solution:triethylamine (100:3:0.5:0.2, v/v/v/v) as the developing system. The accuracy, precision and linearity ranges of the developed methods were determined. The results obtained were statistically compared with each other and to that of a reported HPLC method, and there was no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Three new, simple, sensitive, and accurate stability-indicating methods were developed for quantitative determination of bisacodyl in the presence of its degradation products, monoacetyl bisacodyl (I) and desacetyl bisacodyl (II), in enteric coated tablets, suppositories, and raw material. The first is a spectrodensitometric method in which the drug is separated from I and II on silica gel plates using chloroformacetone (9 + 1, v/v) as the mobile phase with ultraviolet detection of the separated bands at 223 nm over a concentration range of 0.2-1.4 g/band for bisacodyl with mean recovery 100.35 ± 1.923%. The second method is fourth derivative D4 spectrophotometry, which allows determination of bisacodyl in the presence of its degradation products in raw material at 223 nm using acetonitrile as the solvent with adherence to Beer's law over the concentration range 2-18 μg/mL with mean recovery 99.77 ± 1.056%. In the third method, the spectrophotometric data of bisacodyl, I, and II using absolute ethanol as solvent were processed by 3 chemometric techniques: classical least-squares, principal component regression, and partial least-squares. A training set consisting of 15 mixtures containing different ratios of bisacodyl, I, and II was used for construction of the 3 models. A validation set consisting of 6 mixtures was used to validate the prediction ability of the suggested models. The 3 chemometric methods were applicable over a concentration range between 2-14 μg/mL for bisacodyl with mean recovery of 99.97 ± 0.865, 100.01 ± 0.749, and 99.97 ± 0.616% for the 3 models, respectively. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied to the analysis of raw material and pharmaceutical formulations containing bisacodyl, except for the second method that applies only for raw material. The validity of the suggested procedures was further assessed by applying the standard addition technique; the recoveries obtained were in accordance with those given by the reference method.

Three new, different, simple, sensitive, and accurate methods were developed for quantitative determination of nifuroxazide (I) and drotaverine hydrochloride (II) in a binary mixture. The first method was spectrophotometry, which allowed determination of I in the presence of II using a zero-order spectrum with an analytically useful maximum at 364.5 nm that obeyed Beer's law over a concentration range of 2-10 μg/mL with mean percentage recovery of 100.08±0.61. Determination of II in presence of I was obtained by second derivative spectrophotometry at 243.6 nm, which obeyed Beer's law over a concentration range of 2-10 μg/mL with mean recovery of 99.82±1.46%. The second method was spectrodensitometry, with which both drugs were separated on a silica gel plate using chloroformacetonemethanolglacial acetic acid (6 + 3 + 0.9 + 0.1) as the mobile phase and ultraviolet (UV) detection at 365 nm over a concentration range of 0.2-1 μg/band for both drugs, with mean recoveries of 99.99 0.15 and 100.00 0.34% for I and II, respectively. The third method was reversed-phase liquid chromatography using acetonitrilewate (40 + 60, v/v; adjusted to pH 2.55 with orthophosphoric acid) as the mobile phase and pentoxifylline as the internal standard at a flow rate of 1 mL/min with UV detection at 285 nm at ambient temperature over a concentration range of 2-10 μg/mL for both drugs, with mean recoveries of 100.24±1.51 and 100.08±0.78% for I and II, respectively. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulations containing the above drugs with no interference from other dosage form additives. The validity of the suggested procedures was further assessed by applying the standard addition technique which was found to be satisfactory, and the percentage recoveries obtained were in accordance with those given by the EVA Pharma reference spectrophotometric method.

Three simple, rapid, and accurate techniques have been developed for the determination of chlordesmethyldiazepam. The first one depends on the spectrophotometric determination of the orange azodye resulting from the coupling of thymol with the acid induced hydrolysis product of chlordesmethyldiazepam after conversion to the corresponding diazonium salt. The second is the application of quantitative densitometry for the simultaneous determination of chlordesmethyldiazepam in the presence of its degradation product. While the third technique implies HPLC resolution efficiency in the determination of chlordesmethyldiazepam in the presence of its degradation product. The validity of the proposed procedures were proved using the standard addition technique and laboratory prepared mixtures of the drug and its degradation product(s). The proposed procedures were successfully applied for the drug analysis in Tablet form.

Two selective, sensitive and reproducible methods for the determination of carbimazole are described. The spectrophotometric determination of carbimazole was achieved through its reaction with a known excess of potassium bromate in bromide solution, then residual reagent was treated with sodium fluorescein in buffered medium at pH 5.5, where equivalent eosin is produced, which absorbed maximally at 517 nm. Stoichiometric study of the reaction showed that, carbimazole reacts with potassium bromate in the ratio of 1:1. The spectrophotometric method is linear over a range of 30–110 μg%. The spectrodensitometric analysis provides a rapid and precise method for the separation and quantitation of carbimazole. The method depends on the quantitative densitometric evaluation of thin layer chromatogram of carbimazole at 291 nm. It determines the drug in concentration range of 5–22.5 μg per spot. The two methods retained their accuracy and precision when applying the standard addition technique. The results obtained...

Two chromatographic methods were developed for analysis ofdiiodohydroxyquinoline (DIHQ) and metronidazole (MTN). In the first method, diiodohydroxyquinoline and metronidazole were separated on TLC silica gel 60F254 plate using chloroform: acetone: glacial acetic acid (7.5: 2.5: 0.1, by volume) as mobile phase. The obtained bands were then scanned at 254 nm. The second method is a RP-HPLC method in which diiodohydroxyquinoline and metronidazole were separated on a reversed-phase C18 column using water : methanol (60 :40, V/V, PH=3.6 )as mobile phase at a flow rate of 0.7 mL.min-1 and UV detection at 220 nm. The mentioned methods were successfully used for determination of diiodohydroxyquinoline and metronidazole in pure form and in their pharmaceutical formulation.

Hyoscine N-Butyl Bromide (HBB) was subjected to different ICH prescribed stress conditions. It showed extensive decomposition under base hydrolytic conditions, while it was less liable to stress acid hydrolytic conditions. It showed also moderate degradation in response to oxidation stress of hydrogen peroxide. The drug showed no changes under photolysis conditions. In total, a number of major degradation products were detected by HPLC and identified by LC-MS. For establishment of stability-indicating assay, the reaction solutions in which different degradation products were formed were prepared, and the separation was optimized by varying the HPLC conditions. An acceptable chromatograms was achieved using a C18 column using (water: methanol 50: 50 v/v, pH adjusted to 3.9 with triflouroacetic acid) as a mobile phase with flow rate of 1.0 ml min−1 and UV detection wavelength at 210 nm. The percent of degradation was calculated in each run by measuring the intensity of the peak area of the intact drug at 6.2 min. Complete degradation only occur in case of 5 N NaOH indicates that the drug is very sensitive to alkaline hydrolysis. The LC-MS study was carried out to identify the major degradation products using a sunfire (waters) C-18 column and a mobile phase comprising of acetonitrile: 0.1M ammonium acetate (80:20, v/v) with flow rate of 1.0 ml min−1. MS measurements were acquired in positive ion full scan modes from 50 to 400 amu. The m/z values of the main peaks were investigated with the expected chemical structure of degradates.

A rapid, sensitive and specific procedure for determination of ibuprofen has been developed. The drug solution in chloroform is treated with Cu(II) solution at pH 5.5, forming a blue compound which is extractable in the organic phase. This complex is spectrophotometrically measured at λ 675 nm obeying Beer's Law in a concentration range of 0.5 — 3.2 mg.ml-1. Accurate and precise results are obtained with mean percentage recovery of 100.13 ± 1.25. The obtained complex has an apparent molar absorptivity of 0.48 × 102 and bears no interference from other metal ions. The stoichiometry of the reaction was studied and the reaction product was isolated for further studies. The procedure has been successfully carried out for analysis of Brufen tablets and its validity was checked by applying the standard addition technique.

Two specific, sensitive, and precise stability indicating chromatographic methods have been developed, optimized, and validated for Hydrochlorothiazide (HCT) and Spironolactone (SPR) determination in their mixtures and in presence of their impurities and degradation products. The first method was based on thin layer chromatographic (TLC) combined with densitometric determination of the separated spots. The separation was achieved using silica gel 60 F(254) TLC plates and ethyl acetate-chloroform-formic acid-triethyl amine (7:3:0.1:0.1, by volume) as a developing system. Good correlations were obtained between the integrated peak area of the studied drugs and their corresponding concentrations in different ranges. The second method was based on the high-performance liquid chromatography with ultraviolet detection, by which the proposed components were separated on a reversed phase C(18) analytical column using gradient elution system with deionized water-acetonitrile (97:3, v/v) for 8 min. Then acetonitrile was successively increased to 35% in the next 2 min, and kept constant in the following 10 min, finally 3% acetonitrile was regained again to stabilize the chromatographic system. The flow rate was maintained at 2 mL/min and the detection wavelength was at 230 nm. Linear regressions were obtained in the range of 4.0-50 μg/mL and 5.0-50 μg/mL for both HCT and SPR, respectively. 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. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for determination of HCT and SPR in their commercial tablets. Both methods were also statistically compared to each other and to the reported method with no significant difference in performance.

Two accurate and sensitive spectrophotometric and spectrofluorimetric methods were developed for determination of Racecadotril. In the first method reduction of Fe3+ into Fe2+ in presence of o-phenanthroline by Racecadotril to form a stable orange-red ferroin chelate [Fe-(Phen)3]2+ was the basis for its determination. The absorbance at 510 nm was measured and linear correlation was obtained in the concentration range of 2.5-25 µg mL(-1). In the second method the native fluorescence of Racecadotril in acetonitrile solvent at λ=319 nm when excitation was at 252 nm is used for its determination. Linear correlation was obtained in the concentration range of 50 to 500 ng mL(-1). The proposed methods were applied for determination of Racecadotril in bulk powder with mean accuracy of 100.39±1.239 for the spectrophotometric method and 100.09±1.042 for the spectrofluorimetric method. The proposed methods were successfully applied for determination of Racecadotril in its pharmaceutical dosage form.

Validated sensitive and highly selective stability indicating methods are adopted for simultaneous quantitative determination of sulpiride and mebeverine hydrochloride in presence of their reported impurities and hydrolytic degradates whether in pure forms or in pharmaceutical formulation. The first method is High Performance Liquid Chromatography, where the mixture of sulpiride and mebeverine hydrochloride together with the reported interferents plus metopimazine as internal standard are separated on a reversed phase cyano column (5 microm ps, 250 mm x 4.6 id) using acetonitrile: water (70:30 v/v) adjusted to pH = 7 as a mobile phase. The drugs were detected at 221 nm over a concentration range of 5-40 microg ml(-1) and 5-60 microg ml(-1) with mean percentage recoveries 99.75% (S.D. 0.910) and 99.99% (S.D. 0.450) for sulpiride and mebeverine hydrochloride respectively. The second method is High Performance Thin Layer Chromatography, where sulpiride and mebeverine hydrochloride are separated on silica gel HPTLC F(254) plates using absolute ethanol:methylene chloride:triethyl amine (7:3:0.2 by volume) as mobile phase and scanning of the separated bands at 221 nm over a concentration range of 0.4-1.4 and 0.2-1.6 microg band(-1) with mean percentage recoveries 101.01% (S.D. 1.991) and 100.40% (S.D. 1.868) for sulpiride and mebeverine hydrochloride respectively.

Hydrochlorothiazide (HCT) and spironolactone (SPR) are mostly co-formulated in antihypertensive formulations. Several methods have been developed and validated for their determination; these methods include spectrophotometric and chemometric-assisted spectrophotometric methods. The developed spectrophotometric methods were isosbestic point (ISO) and ratio subtraction (RS) methods. The absorbance values at 232.4 (λiso1) and 257.6 nm (λiso2) were used for determination of the total mixture concentration, while HCT could be directly determined at 317.2 nm (λmax) and by subtraction SPR concentration could be obtained. Also SPR concentration could be calculated by RS method using the absorbance at 243.8 nm (λmax). A wavelength selection method based on genetic algorithm (GAs) was developed and compared to the conventional partial least squares method (PLS). In this method, several parameters were adjusted and the optimum parameter settings were determined using experimental design. The developed chemometric methods were successfully applied for the determination of the HCT and SPR, as well as for determination of their impurities and degradation products. The proposed methods were successfully applied for determination of HCT and SPR in commercial tablets and they were statistically compared to each other and to the reported method. No significant difference was found, providing their accuracy and precision. Copyright © 2010 John Wiley & Sons, Ltd.

Sensitive and validated UV-spectrophotometric, chemometric and TLC-densitometric methods were developed for determination of triamterene (TRM) and xipamide (XIP) in their binary mixture, formulated for use as a diuretic, without previous separation. Method A is the isoabsorptive point spectrophotometry, in which TRM concentration alone can be determined at its λmax while XIP concentration can be determined by measuring total concentration of TRM and XIP at their isoabsorptive point followed by subtraction. Method B is the ratio subtraction spectrophotometry, where XIP can be determined by dividing the spectrum of the mixture by the spectrum of TRM (as a divisor) followed by subtracting the constant absorbance value of the plateau region, then finally multiplying the produced spectrum by the spectrum of the divisor, while TRM concentration can be determined at its λmax. Method C is a chemometric-assisted spectrophotometry where classical least squares, principal component regression, and partial least squares were applied. Method D is a TLC-densitometry; this method depends on quantitative densitometric separation of thin layer chromatogram of TRM and XIP using silica gel plates at 254 nm. The proposed methods were successfully applied for the analysis of TRM and XIP in their pharmaceutical formulation and the results were statistically compared with the established HPLC method. Copyright © 2010 John Wiley & Sons, Ltd.

Four sensitive, selective and precise stability-indicating methods for the determination of Clopidogrel Bisulfate (CLP) in presence of its alkaline degradate and in pharmaceutical formulations were developed and validated. Method A is a second derivative (D(2)) spectrophotometric one, which allows the determination of CLP in presence of its alkaline degradate at 219.6, 270.6, 274.2 and 278.4 nm (corresponding to zero-crossing of the degradate) over a concentration range of 4-37 microg mL(-1) with mean percentage recoveries 99.81+/-0.893, 99.72+/-0.668, 99.88+/-0.526 and 100.46+/-0.646, respectively. CLP can be determined in the presence of up to 65% of its degradate. D(2) method was used to study the kinetic of CLP alkaline degradation that was found to follow a first-order reaction. The t(1/2) was 6.42 h while K (reaction rate constant) was 0.1080 mol/h. Method B is the first derivative of the ratio spectra (DD(1)) spectrophotometric method, by measuring the peak amplitude at 217.6 and 229.4 nm using acetonitrile and CLP can be determined in the presence of up to 70% of its degradate. The linearity range was 5-38 microg mL(-1) with mean percentage recoveries 99.88+/-0.909 and 99.70+/-0.952, respectively. Method C based on the determination of CLP by the bivariate calibration depending on simple mathematic algorithm which provides simplicity and rapidity. The method depends on quantitative evaluation of the absorbance at 210 and 225 nm over a concentration range 5-38 microg mL(-1) with mean percentage recovery 99.27+/-1.115. CLP can be determined in the presence of up to 70% of its degradate. Method D is a TLC-densitometric one, where CLP was separated from its degradate on silica gel plates using hexane:methanol:ethyl acetate (8.7:1:0.3, v/v/v) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of CLP at 248 nm over a concentration range of 0.6-3 microg/band with mean percentage recovery 99.97+/-1.161. CLP can be determined in the presence of up to 90% of its alkaline degradate. The selectivity of the proposed methods was checked using laboratory prepared mixtures. The proposed methods have been successfully applied to the analysis of CLP in pharmaceutical dosage forms without interference from other dosage form additives and the results were statistically compared with the official method.

Three new, simple, sensitive, and accurate stability-indicating methods were developed for quantitative determination of bisacodyl in the presence of its degradation products, monoacetyl bisacodyl (I) and desacetyl bisacodyl (II), in enteric coated tablets, suppositories, and raw material. The first is a spectrodensitometric method in which the drug is separated from I and II on silica gel plates using chloroform-acetone (9 + 1, v/v) as the mobile phase with ultraviolet detection of the separated bands at 223 nm over a concentration range of 0.2-1.4 microg/band for bisacodyl with mean recovery 100.35 +/- 1.923%. The second method is fourth derivative D4 spectrophotometry, which allows determination of bisacodyl in the presence of its degradation products in raw material at 223 nm using acetonitrile as the solvent with adherence to Beer's law over the concentration range 2-18 microg/mL with mean recovery 99.77+/-1.056%. In the third method, the spectrophotometric data of bisacodyl, I, and II using absolute ethanol as solvent were processed by 3 chemometric techniques: classical least-squares, principal component regression, and partial least-squares. A training set consisting of 15 mixtures containing different ratios of bisacodyl, I, and II was used for construction of the 3 models. A validation set consisting of 6 mixtures was used to validate the prediction ability of the suggested models. The 3 chemometric methods were applicable over a concentration range between 2-14microg/mL for bisacodyl with mean recovery of 99.97+/-0.865, 100.01 +/- 0.749, and 99.97 +/- 0.616% for the 3 models, respectively. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied to the analysis of raw material and pharmaceutical formulations containing bisacodyl, except for the second method that applies only for raw material. The validity of the suggested procedures was further assessed by applying the standard addition technique; the recoveries obtained were in accordance with those given by the reference method.

Spectrophotometric, spectrodensitometric and HPLC are stability indicating methods described for determination of Zaleplon in pure and dosage forms. As Zaleplon is easily degradable, the proposed techniques in this manuscript are adopted for its determination in presence of its alkaline degradation product, namely N-[4-(3-cyano-pyrazolo[1,5a]pyridin-7-yl)-phenyl]-N-ethyl-acetamide. These approaches are successfully applied to quantify Zaleplon using the information included in the absorption spectra of appropriate solutions. The second derivative (D(2)) spectrophotometric method, allows determination of Zaleplon without interference of its degradate at 235.2 nm using 0.01N HCl as a solvent with obedience to Beer's law over a concentration range of 1-10 microg ml(-1) with mean percentage recovery 100.24+/-0.86%. The first derivative of the ratio spectra ((1)DD) based on the simultaneous use of ((1)DD) and measurement at 241.8 nm using the same solvent and over the same concentration range as (D(2)) spectrophotometric method, with mean percentage recovery 99.9+/-1.07%. The spectrodensitometric analysis allows the separation and quantitation of Zaleplon from its degradate on silica gel plates using chloroform:acetone:ammonia solution (9:1:0.2 by volume) as a mobile phase. This method depends on quantitave densitometric evaluation of thin layer chromatogram of Zaleplon at 338 nm over a concentration range of 0.2-1 microg band(-1), with mean percentage recovery 99.73+/-1.35. Also a reversed-phase liquid chromatographic method using 5-C8 (22 cm x 4.6 mm i.d. 5 microm particle size) column was described and validated for quantitation of Zaleplon using acetonitrile:deionised water (35:65, v/v) as a mobile phase using Paracetamol as internal standard and a flow rate of 1.5 ml min(-1) with UV detection of the effluent at 232 nm at ambient temperature over a concentration range of 2-20 microg ml(-1) with mean percentage recovery 100.19+/-1.15%. The insignificance difference of the proposed methods results with those of the reference one proved their accuracy and precision.

Different sensitive and selective spectrophotometric methods for the determination of ofloxacin and dexamethasone in their binary mixture were presented. Ofloxacin was determined simply by zero order at its λmax 293.4 nm in a linear range of 1.5–12 μg mL−1 with mean percentage recovery of 100.07 ± 0.66% without any interference of dexamethasone even in low or high concentrations. Dexamethasone was determined by first derivative of ratio spectra 1DD at 266.5 nm, ratio subtraction and mean centering at 243 nm with methods in a linear range of 2.5–27.5 μg mL−1 with mean percentage recoveries of 100.09 ± 0.70%, 100.00 ± 0.72% and 99.92 ± 0.62, respectively. These methods were applied to the analysis of pharmaceutical dosage form and bulk powder where good recoveries were obtained. The proposed methods were validated according to USP guidelines.