Synchronous Fluorescence as a Green and Selective Method for the Simultaneous Determination of Cetirizine and Azelastine in Aqueous Humor.

A green, simple, quick and economical method is implemented for the first time for the simultaneous estimation of cetirizine (CTZ) and azelastine (AZE) as co-administered eye drops. The method relies on synchronous spectrofluorimetry with ∆λ = 60 nm. Cetirizine can be estimated at 231 nm and AZE can be measured at 294 nm, each at the other's zero crossing point. All factors affecting the method were studied and properly optimized. Good correlation was obtained in the range of 0.1-2 µg mL-1 for both drugs. The limits of detection were 0.014 and 0.010 µg mL-1 and limits of quantitation were 0.043 and 0.029 µg mL-1 for CTZ and AZE, respectively. Moreover, ICH guidelines were carried out to validate the adopted method. The method was suitable for the analysis of CTZ and AZE in synthetic mixtures, eye drops and aqueous humor. The mean percentage of recoveries of CTZ and AZE in spiked aqueous humor were 99.83 and 99.37, respectively. Furthermore, Green Analytical Procedure Index (GAPI) and analytical Eco-scale approaches were used to evaluate the greenness of the suggested method.

Concurrent estimation of some co-administered antimicrobial drugs applying conventional and first derivative synchronous fluorescence spectroscopy techniques.

For the estimation of some co-administered antimicrobials, two highly accurate and precise spectrofluorimetric methods were developed. Fluconazole (FLZ) is co-administered with either ciprofloxacin (CPR) or ofloxacin (OFX) for the treatment of certain microbial infections. On the other hand, another antimicrobial drug, vancomycin (VNC) is co-administered with ciprofloxacin (CPR) for peritonitis treatment. In method I, conventional spectrofluorimetry has been introduced for the concurrent quantitative estimation of FLZ in presence of OFX or CPR. While in method II, a first derivative synchronous spectrofluorimetric technique was adapted for quantitation of VNC and CPR co-administered combination. Both of them were utilized for estimation of the considered drugs in raw materials, laboratory prepared mixtures, dosage forms, and biological fluids. Method I was relied on simultaneous measuring of the native fluorescence of FLZ and OFX or CPR without any overlapping between the emission spectra of each binary mixture (FLZ / OFX) and (FLZ / CPR). Fluorescence intensities were measured at 283.0, 483.0 and 436.0 nm after excitation at 262.0, 292.0 and 275.0 nm for FLZ, OFX and CPR, respectively. Method II was utilized the synchronous fluorescence intensity of VNC and CPR in methanol at Δλ = 40 nm. The first derivative synchronous spectra were calibrated at 297.0 nm for VNC and at 379.5 nm for CPR. Different variables influencing conventional and synchronous fluorescence intensities of the four antimicrobials under investigation were precisely optimized. Both methods were successfully investigated for the determination of the studied drugs in plasma. The linear data analysis for the calibration curves reveals a good relationship in the ranges of 1.0-10.0, 0.25-2.5 and 0.06-0.6 µg/mL for FLZ, OFX and CPR for method I with limits of detection 0.144, 0.038 and 0.007 µg/mL and limits of quantitation of 0.437, 0.114 and 0.021 µg/mL for FLZ, OFX and CPR, respectively. Linearity range for method II was 0.5 -10.0 µg/mL for VNC and CPR with detection limits of 0.127 and 0.110 µg/mL and quantitation limits of 0.380 and 0.334 µg/mL for VNC and CPR, respectively. International Council on Harmonization ICH Q2 (R1) Guidelines were followed in the developed methods validation. The achieved outcomes were statistically compared with those found by the reported ones, and no significant difference was observed.

Green and sensitive spectrofluorimetric method for the determination of two cephalosporins in dosage forms.

Using two green and sensitive spectrofluorimetric methods, we quantified two cephalosporins, cefepime (CFM) and cefazolin (CFZ), in raw and pharmaceutical formulations. The first method is based on the reaction between CFM and fluorescamine (borate buffer, pH 8), which yields a highly fluorescent product. After excitation at 384 nm, the fluorescent product emits light at 484 nm. At concentration ranges from 12.0 to 120.0 ng ml-1, the relative fluorescence intensity/concentration curve was linear with a limit of quantification (LOQ) of 2.46 ng ml-1. The second method relied on measuring the CFZ quenching action on acriflavine fluorescence through formation of an ion-associate complex using Britton-Robinson buffer at pH 8. We measured acriflavine fluorescence at 505 nm after excitation at 265 nm. The decrease in acriflavine fluorescence intensity was CFZ concentration-dependent. Using this method, we quantified CFZ in concentrations ranging from 1 to 10 µg ml-1 with a LOQ of 0.48 µg ml-1. We studied and optimized the factors influencing reaction product formation. Moreover, we adapted our methods to the investigation of the mentioned drugs in raw and pharmaceutical formulations with greatly satisfying results. We statistically validated our methods according to International Council on Harmonisation Guidelines. The obtained results were consistent with those obtained with the official high-performance liquid chromatography methods.

Investigation of some univariate and multivariate spectrophotometric methods for concurrent estimation of Vancomycin and Ciprofloxacin in their laboratory prepared mixture and application to biological fluids.

Four simple, rapid, accurate and precise spectrophotometric methods were established and validated in accordance with ICH Q2 (R1) guidelines for the simultaneous determination of Vancomycin (VNC) and Ciprofloxacin (CPR) in their raw materials, laboratory prepared mixtures and pharmaceutics. Method A depends on using first derivative spectrophotometry (D1) where VNC and CPR were resolved at 243.6 and 262.0 nm, respectively. Concerning method B, it is based on utilizing first derivative of ratio spectra (DD1) where determination was performed at the peak maxima at 244.0 nm and 258.0 nm for VNC and CPR, respectively. Two chemometric models were applied for the quantitative analysis of both drugs in their laboratory prepared mixtures, namely, partial least squares (PLS) (method C) and artificial neural network (ANN) (method D). For univariate methods linearity range for both drugs was in the range of 3-30 and 1-10 µg/mL for VNC and CPR, respectively. Multivariate calibration methods using five level, two factor calibration model for the development of 25 mixtures were also applied for the simultaneous estimation of the two drugs in their laboratory prepared mixture using spectral region from 200.0 to 300.0 nm using interval 1 nm. The suggested methods have been successfully extended to the assay of the two studied drugs in laboratory-prepared mixtures and pharmaceuticals with excellent recovery. First derivative spectrophotometry (D1) was also applied for the assay of both analytes in spiked human plasma with good recovery. No interaction with common pharmaceutical additives has been observed which indicate the selectivity of the method. The results obtained were favourably compared with those obtained applying the reported methods. The methods are validated in compliance with the ICH Q2 (R1) guidelines and the measured accuracy and precision are assessed to be within the accepted limits.

Cytogenetic effects of pesticides. IV. Cytogenetic effects of the insecticides Gardona and Dursban.

The cytogenetic effects of the insecticides Gardona and Dursban were investigated. The toxicity and ability of both insecticides to induce chromosome aberrations and sister-chromatid exchange in vitro was tested in a primary culture of mouse spleen cells, in order to assess the potential mutagenicity of both insecticides. The concentrations 10(-7)-10(-3) M were used for testing the toxic effects of the insecticides. Both Gardona and Dursban were toxic to spleen cell cultures and the percentage of viable cells decreased as the concentration of the insecticide was increased. It reached 76.8% and 77.8% of control after treatment with the highest concentration tested (10(-3) M) of Gardona and Dursban respectively. Gardona at 0.25, 0.50, 1.0 and 2.0 micrograms/ml, and Dursban at 0.50, 1.0, 2.0 and 4.0 micrograms/ml were tested for the induction of chromosome aberrations and sister-chromatid exchanges. All of the tested concentrations of both insecticides induced a high percentage of metaphases with chromosomal aberrations in cultured mouse spleen cells after 4-h treatment. The frequency of SCEs/cell increased with increasing concentration of the insecticides. It reached 11.92 +/- 0.14/cell and 13.40 +/- 0.20/cell after treatment with Gardona (2 micrograms/ml) and Dursban (4 micrograms/ml), respectively, compared with 8.2 +/- 0.19/cell and 7.6 +/- 0.15/cell in the solvent control. The presented results indicate that both Gardona and Dursban in the tested concentrations are mutagenic in mouse spleen cell cultures.

Genotoxic effect of 2,4-dichlorophenoxy acetic acid and its metabolite 2,4-dichlorophenol in mouse.

The cytogenetic effect of 2,4-dichlorophenoxy acetic acid (2,4-D) and its metabolite 2,4-dichlorophenol (2,4-DCP) was studied in bone-marrow, germ cells and sperm head abnormalities in the treated mice. Swiss mice were treated orally by gavage with 2,4-D at 1.7, 3.3 and 33 mg kg(-1)BW (1/200, 1/100 and 1/10 of LD(50)). 2,4-DCP was intraperitoneally (i.p.) injected at 36, 72 and 180 mg kg(-1)BW (1/10, 1/5, 1/2 of LD(50)). A significant increase in the percentage of chromosome aberrations in bone-marrow and spermatocyte cells was observed after oral administration of 2,4-D at 3.3 mg kg(-1)BW for three and five consecutive days. This percentage increased and reached 10.8+/-0.87 (P<0.01) in bone-marrow and 9.8+/-0.45 (P<0.01) in spermatocyte cells after oral administration of 2,4-D at 33 mg kg(-1)BW for 24 h. This percentage was, however, lower than that induced in bone-marrow and spermatocyte cells by mitomycin C (positive control). 2,4-D induced a dose-dependent increase in the percentage of sperm head abnormalities. The genotoxic effect of 2,4-DCP is weaker than that of 2,4-D, as indicated by the lower percentage of the induced chromosome aberrations (in bone-marrow and spermatocyte cells) and sperm head abnormalities. Only the highest tested concentration of 2,4-DCP (180 mg kg(-1)BW, 1/2 LD(50)) induced a significant percentage of chromosome aberrations and sperm head abnormalities after i.p. injection. The obtained results indicate that 2,4-D is genotoxic in mice in vivo under the conditions tested. Hence, more care should be given to the application of 2,4-D on edible crops since repeated uses may underlie a health hazard.

Evaluation of certain pharmaceuticals with hexa-amminecobalt(III) tricarbonatocobaltate(III)-I Determination of some N-substituted phenothiazine derivatives.

Hexa-amminecobalt(III) tricarbonatocobaltate(III) (HCTC) has been used for the determination of six N-substituted phenothiazine derivatives. The drugs in 10% v/v sulphuric acid medium were titrated with 5 x 10(-3)M HCTC with visual or spectrophotometric end-point detection. The stoichiometry of the reaction was assumed and a reaction mechanism suggested. The methods were applied to the analysis of dosage forms with results comparable to those given by the official methods.

Fluorometric determination of reserpine in dosage forms.

A rapid and highly sensitive fluorometric procedure has been developed for the routine determination of reserpine, in bulk and in dosage forms. The method is based on the fluorescence induced by oxidation of reserpine with hexa-amminecobalt(III) tricarbonatocobaltate in aqueous acetic acid. The oxidation product exhibits a greenish yellow fluorescence with its emission maximum at around 420 nm. The fluorescence intensity is a linear function of reserpine concentration over the range 0.01-0.24 mug/ml in the solution finally measured. The advantages and disadvantages of the proposed method are discussed, and its applicability to different formulations is demonstrated.

Differential pulse polarographic determination of ofloxacin in pharmaceuticals and biological fluids.

A sensitive method is described for the determination of ofloxacin in its pure form, dosage forms and biological fluids. The proposed method depends upon the polarographic activity of ofloxacin in Britton Robinson buffers, whereby a well-defined cathodic wave is produced over the pH range 4.1-10.3. The wave was characterized as being irreversible, diffusion-controlled with limited adsorption properties. The current-concentration relationship was found to be rectilinear over the range 5x10(-5)-5x10(-4) M and 1x10(-5)-5x10(-4) M using the DC(t) and DPP modes respectively, with a minimum detectability (S/N=3) of 3x10(-7) M. The proposed method was successfully applied to the determination of ofloxacin in tablets and biological fluids. The results obtained were found to be in agreement with those obtained by a reference method.

Permanganate-based chemiluminescence analysis of cefadroxil monohydrate in pharmaceutical samples and biological fluids using flow injection.

A chemiluminescent method using flow injection is described for the determination of cefadroxil monohydrate. The method is based on the chemiluminescence reaction of cefadroxil with potassium permanganate in sulphuric acid, sensitized by quinine. The proposed procedure allows the determination of cefadroxil over the concentration range 0.1-30 mug ml(-1) with a detection limit of 0.05 mug ml(-1) and a sample measurement frequency of 150 samples h(-1). The method was successfully applied to the determination of cefadroxil in pharmaceutical preparations and biological fluids.

Fluorometric determination of some thioxanthene derivatives in dosage forms.

A simple, highly sensitive method is presented for the determination of five pharmaceutically important thioxanthene derivatives, namely chlorprothixene, thiothixene, methixene hydrochloride, clopenthixol hydrochloride and flupentixol hydrochloride. The method involves the use of hexaamminecobalt(III) tricarbonatocobaltate(III) (HCTC) as an oxidant in aqueous sulphuric acid medium to induce fluorescence. The proposed method has been further applied to the determination of the five compounds in their dosage forms. The results compare favourably with those obtained by the official methods.

Spectrofluorimetric determination of prenalterol hydrochloride in pharmaceutical preparations and biological fluids.

A simple and highly sensitive fluorimetric method was developed for the routine determination of prenalterol hydrochloride in bulk, in dosage forms and in biological fluids. The method is based on the fluorescence induced by reaction of the nitroso-derivative of prenalterol hydrochloride with 2-cyanoacetamide in the presence of ammonia. The different experimental parameters were carefully studied and incorporated into the procedure. The fluorescence is measured at 440 nm after excitation at 368 nm. Fluorescence intensity is a linear function of prenalterol hydrochloride concentration over the range of 0.1-2.8 microg x ml(-1) in the solution finally measured. A proposal for the reaction pathway was suggested.

Fluorimetric determination of prenalterol hydrochloride in pharmaceuticals and biological fluids based on its oxidation reaction by hexacyanoferrate(III).

A rapid and sensitive fluorimetric method for the determination of prenalterol hydrochloride is presented, based on the oxidation of the analyte with potassium hexacyanoferrate(III) in a slightly alkaline medium (pH 9.23). The different experimental parameters were carefully studied and incorporated into the procedure. The oxidation product exhibits a blue fluorescence with its emission maximum at 427 nm, and excitation maximum at 314 nm. Fluorescence intensity is a linear function of prenalterol hydrochloride concentration over the range of 0.2-3.6 microg/ml(-1) in the solution finally measured. The method was successfully applied to the determination of prenalterol hydrochloride in pharmaceutical formulations and biological fluids. A proposal for the reaction pathway is suggested.

UV-spectrophotometric determination of ampicillin sodium and sulbactam sodium in two-component mixtures.

A simple spectrophotometric method is used for the resolution of the binary mixtures of ampicillin sodium and sulbactam sodium. In aqueous solution, zero-order spectra are subject to interference, so first-derivative spectrophotometry was used to enhance the spectral details allowing the determination of ampicillin sodium from the signal at the zero-crossing point for sulbactam sodium at 268 nm. In 0.1 N sodium hydroxide, sulbactam sodium was determined from the absorbance at 260 nm with negligible contribution from ampicillin sodium. Also, sulbactam sodium was determined without interference using first- and second-derivative spectra in 0.1 N sodium hydroxide at 276 nm (peak-height) and 262-284 nm (peak-to-peak), respectively. The method is rapid, simple, does not require a separation step and allows the determination of each drug without interference from the other. The proposed method has been applied successfully to the assay of these drugs in mixtures and in commercial injections.

Polarographic determination of prenalterol hydrochloride through treatment with nitrous acid.

A simple and sensitive polarographic method is described for the determination of prenalterol hydrochloride through treatment with nitrous acid. The different experimental parameters affecting the derivatization process, as well as the polarographic analysis were studied. The derivatization product was found to be reducible at the dropping mercury electrode over the whole pH range in Britton-Robinson buffers. At pH 5, a well defined diffusion-controlled cathodic wave was produced. The limiting current vs. the concentration plot was linear over the range 0.015-0.15 mM in the direct current mode, with a minimum detectability of 0.8 microM. The proposed method was applied successfully to the determination of prenalterol hydrochloride either in the pure form or in its dosage forms.

Analysis of pharmaceutically-important thioxanthene derivatives.

A review with 92 references is presented that deals with the reported methods of analysis of the thioxanthene derivatives of pharmaceutical interest. The review includes the methods adopted in dosage forms and biological fluids. A brief discussion of the metabolism and pharmacokinetics of this class of compounds is also reported.

Spectrophotometric determination of some MAO inhibitors using 7,7,8,8-tetracyanoquinodimethane and iodine monochloride.

Two simple and sensitive spectrophotometric methods are described for the assay of three MAO inhibitors: isocarboxazid, tranylcypromine sulphate and iproniazid phosphate. The first method is based on the formation of a highly coloured stable radical anion between the drug as an n-donor and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as a pi-electron acceptor. Beer's law is obeyed in the concentration range 0.2-3, 0.2-4 and 0.5-4 micrograms ml-1 for isocarboxazid, tranylcypromine sulphate and iproniazid phosphate, respectively. The second method involves the use of iodine monochloride (ICl) as an sigma-acceptor. It was found that ICl reacts quantitatively only with isocarboxazid and tranylcypromine sulphate; with iproniazid phosphate results were very poor. Beer's law is obeyed in the concentration range 2-20 micrograms ml-1 for both drugs. The optimum experimental parameters for colour production in each case were determined. The percentage recoveries obtained were in accordance with those obtained by the official methods. The proposed methods are characterized by high sensitivity.

Polarographic determination of EDTA in certain pharmaceutical dosage forms.

A highly sensitive polarographic method was developed for the determination of EDTA added as a preservative in certain pharmaceutical preparations. The method involved chelation with Eu(III) followed by polarographic measurement of the chelate formed. A well-defined cathodic wave was developed in Britton-Robinson buffers over the pH range 2-12. The wave was characterized as being quasi-reversible and diffusion controlled. The current-concentration relationship was found to be rectilinear over the ranges 8-160 and 2-120 micrograms ml-1, using DCt and DPP modes, respectively, with limit of detection of 0.1 microgram ml-1 using the DDP technique. The mechanism of the electrode reaction was verified. The proposed method was applied for the determination of EDTA in certain pharmaceutical dosage forms, and the results obtained were in agreement with those obtained by a reference method.

Determination of (S)(-)-cathinone by spectrophotometric detection.

Previous studies on the Khat plant (Catha edulis, Celastraceae) illustrated the importance of using freshly harvested young shoots and leaves such that cathinone, the principle active component and Schedule I controlled drug contained within the plant, could be suitably isolated and identified. The purpose of this work was to develop a quantitative analytical technique for the determination of cathinone. The proposed method is based on treating the reductant cathinone with copper(II)-neocuproine reagent in sodium acetate-buffered medium followed by measuring the absorbance of the copper(I)-neocuproine complex at 455 nm. The calibration plot is linear in the range 0.08-25 micrograms ml-1 with a detection limit of 0.08 microgram ml-1. The precision of the method, expressed as the relative standard deviation, is 1.35% for 10 micrograms ml-1 cathinone. Good recoveries have been obtained in applying the method to the analysis of cathinone in Khat leaves.

Flow-injection chemiluminometric determination of some thioxanthene derivatives in pharmaceutical formulations and biological fluids using the [Ru(dipy)3(2+)]-Ce(IV) system.

A flow-injection (FI) methodology using tris(2,2'-dipyridyl)ruthenium(II), [Ru(dipy)3(2+)], chemiluminescence (CL) was developed for the rapid and sensitive determination of three thioxanthene derivatives, namely zuclopenthixol hydrochloride, flupentixol hydrochloride and thiothixene. The method is based on the CL reaction of the studied thioxanthenes with [Ru(dipy)3(2+)] and Ce(IV) in a sulfuric acid medium. Under the optimum conditions, calibration graphs were obtained over the concentration ranges 0.002-6 migrograms/ml for zuclopenthixol hydrochloride, 0.5-15 micrograms/ml for flupentixol hydrochloride and 0.05-7.5 micrograms/ml for thiothixene. The limits of detection (s/n = 3) were 4.2 x 10(-9) mol/l zuclopenthixol hydrochloride, 2 x 10(-8) mol/l flupentixol hydrochloride and 4.5 x 10(-8) mol/l thiothixene. The method was successfully applied to the determination of these compounds in dosage forms and biological fluids.