A bio-analytically validated HPLC-UV method for simultaneous determination of doripenem and ertapenem in pharmaceutical dosage forms and human plasma: a dual carbapenem regimen for treatment of drug-resistant strain of Klebsiella pneumoniae.

The emergence of strains resistant to certain antibiotics is turning into an important issue worldwide that threatens global health with the increasing incidence of carbapenemase-producing Klebsiella pneumoniae (KPC). Thus, successful doripenem-ertapenem (DOR-ERTA) combination is highly recommended in treatment of bacteremic ventilator-associated pneumonia due to Klebsiella pneumoniae. Hence, a fast and highly-sensitive HPLC-UV method was developed for the estimation of the cited drugs simultaneously in their pure form, pharmaceutical dosage forms and in simulated synthetic mixtures. The DOR-ERTA mixture was successfully separated within 6 min on a reversed-phase ODS column using an isocratic elution; a mobile phase mixture consists of 0.05 M phosphate buffer (pH 3.0 adjusted by 85% ortho-phosphoric acid) : acetonitrile : methanol (86 : 12 : 2; % v/v/v). The proposed method was optimized and validated according to ICH guidelines, where the calibration graph was constructed from 0.04 to 50 µg mL-1 and from 0.05 to 50 µg mL-1 with low detection limits reached 1.7 and 1.4 ng mL-1 for DOR and ERTA respectively. The proposed method showed higher sensitivity than several previous methods, which allowed an effective estimation of the DOR and ERTA in human plasma after a simple extraction method with high recovery results ranged from 96.30% ± 1.55 to 97.90% ± 1.45 and without any interference from plasma components.

Applicability of ninhydrin as a fluorescent reagent for estimation of teicoplanin in human plasma using salting-out assisted liquid-liquid extraction technique.

The applicability of ninhydrin, a widely used derivatizing reagent, for determination of teicoplanin (TEIC) in its pure form, pharmaceutical vials, and in human plasma was investigated. The presented spectrofluorimetric method was based on a condensation reaction between ninhydrin and the primary amine group existing in TEIC (in the presence of phenylacetaldehyde) to produce a highly fluorescent product detected at 460 nm (λex ,390 nm). Calibration plots were constructed in the concentration range 60-600 ng mL-1 with a good correlation coefficient of 0.9998 and a low detection limit of 10.84 ng mL-1 . The method was subjected to a bioanalytical validation study according to US-FDA recommendations. The proposed method was applied for analysis of TEIC in commercial vials with high recovery result 101.88 ± 1.11%. In addition, the method was utilized efficiently for detection of TEIC in human plasma using salting-out assisted liquid-liquid extraction technique (SALLE) with a recovery range from 96.71 ± 1.08% to 97.71 ± 0.86%. SALLE is an effective approach used for extraction of TEIC from human plasma without interferences using ammonium sulphate. The proposed method is highly recommended to monitor TEIC in clinical laboratory samples and therapeutic drug monitoring systems.

A rapid FTIR spectroscopic assay for quantitative determination of Memantine hydrochloride and Amisulpride in human plasma and pharmaceutical formulations.

A selective, new, rapid and nondestructive Fourier transform Infrared spectroscopic assay has been developed for simultaneous determination of Memantine hydrochloride and Amisulpride in human plasma and their pharmaceutical formulations without interference from common dugs excipients. A binary mixture of ME and nonselective ß-blocker namely; carvidalol has been determined the solid-state by FTIR spectroscopy for the first time. The linear range had been extent from 1.0 to 8.0 and 1.0 to 10.0 µg/mg, for ME and AMS respectively. The detection limits were 0.29 and 0.23 µg/mg while quantitation limits were 0.90 and 0.71 µg/mg for ME and AMS respectively. The developed assay has been validated according to ICH & USP recommendations and successfully applied for quantitative determination of selected drugs in biological fluid.

Highly sensitive cadmium sulphide quantum dots as a fluorescent probe for estimation of doripenem in real human plasma: application to pharmacokinetic study.

Thioglycolic acid-capped cadmium sulphide quantum dots (TGA-CdS QDs) have been synthesized and utilized as a fluorescent probe for the estimation of doripenem (DOR). Monitoring of DOR in different biological fluids is required to estimate the efficient dose to avoid bacterial infections and resistance. The investigated method is based on the measurement of fluorescence quenching of TGA-CdS QDs after the addition of DOR. The synthesized TGA-CdS QDs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) and ZETA sizer. The TGA-CdS QDs showed unique photophysical properties with high quantum yield (0.32) using a comparison method with rhodamine B. Different experimental parameters affecting the synthesis process of the TGA-CdS QDs and their behavior with the studied drug DOR were examined and optimized. The values of the fluorescence quenching were linearly correlated to DOR concentration over the range of 10-500 ng mL-1 with a good correlation coefficient of 0.9991. The proposed method showed higher sensitivity over several reported methods, with LOD reaching 2.0 ng mL-1. The method was effectively applied for the estimation of DOR in human plasma and urine with good recovery results ranged from 95.16% to 99.51%. Furthermore, the stability of DOR in the human plasma was studied and a pharmacokinetic study of DOR in real human plasma was conducted.

A new spectrofluorimetric assay for quantification of Amisulpride and Memantine hydrochloride in real human plasma sample and pharmaceutical formulations via Hantzsch reaction.

A new, selective and accurate spectrofluorimetric assay has been described for detection of Amisulpride and Memantine hydrochloride in pharmaceutical formulations and real plasma samples. The described assay depends on the reaction between the primary amino group of the selected drugs with acetyl acetone & formaldehyde in an acetate buffer of pH4.8. The derivatized product showed yellow fluorescence at λex=418nm and λem=484.5nm. The calibration graph was linear in the range of 0.05-0.5 and 0.2-1µgmL-1 for AMS and ME, orderly. The limits of detection were 0.0085 and 0.0153µgmL-1, and the limits of quantitation were 0.026 and 0.0464µgmL-1 for AMS and ME respectively. Validation of the described assay was in consonance with ICH guideline. Due to the sensitivity of the prescribed assay, it permits the determination of selected medications in biological sample quantitatively.

Development of sensitive benzofurazan-based spectrometric methods for analysis of spectinomycin in vials and human biological samples.

Spectinomycin hydrochloride (SPEC) is an aminoglycoside antibiotic that has a broad spectrum against several bacterial strains of humans and veterinary infections. However, SPEC lacks a fluorophore or chromophore and this lack makes its analysis a challenge. Our study provides a simple, sensitive and low-cost spectrofluorimetric/spectrophotometric method based on the reaction between secondary amine groups and a benzofurazan reagent using borate buffer (pH 9.2). The yielding compound was measured fluorimetrically at 530 nm (excitation at 460 nm) with colorimetry at 410 nm. The calibration curves ranged from 30 to 400 ng ml-1 and from 0.2 to 6 µg ml-1 for spectrofluorimetric and spectrophotometric analyses, respectively. The limits of detection were calculated to be 4.15 ng ml-1 and 0.05 µg ml-1 for spectrofluorimetric and spectrophotometric processes, respectively. The ultra-affectability and high selectivity of the proposed method permitted analysis of SPEC in the dosage form and in human plasma samples, with good recoveries of about 101.19 and 97.11%, respectively, without any matrix interference. The proposed strategy was validated using International Conference on Harmonization standards and validated bioanalytically using USFDA recommendations.

A new sensitive approach for spectrofluorimetric assay of Milnacipran and Amisulpride in real plasma and pharmaceutical preparations via complexation with Eosin Y dye.

An accurate, economic, rapid, reliable spectrofluorimetric assay was developing for the assay of definite anti-depressant drugs namely Amisulpride and Milnacipran hydrochloride, in those pharmaceutical preparation and biological fluid. The suggested method was established on the detection of quenching process resulting from the action of AMS and MCN to the native fluorescent EosinY. A binary complex between selected medications and Eosin Y was established in acetate buffer (0.2 M) at pH 3.3 & 4.0 for AMS and MCN respectively. The relative fluorescence capacity was determined at λex = 301.8 nm and λem = 542.7 nm. The calibration graphs had been linear through extent from 0.02 to 0.3 and 0.1-1 µg mL-1, to both dugs respectively. Detection limits have been 0.0047 & 0.0188 µg mL-1 while quantitation limits have been 0.0141 & 0.0569 µg mL-1 to AMS & MCN respectively. Developed assay has been validated in agreement with ICH recommendations. Due to high sensitivity of the described assay, it allows the quantitation of anti-depressant drugs through biological fluid.

Utility of the fluorogenic characters of benzofurazan for analysis of tigecycline using spectrometric technique; application to pharmacokinetic study, urine and pharmaceutical formulations.

Tigecycline (TIGE) is the newest tetracycline derivative antibiotic with low toxicity, it is used for management of infectious diseases caused by Gram-positive and Gram-negative bacteria. Hence, an efficient, selective and sensitive method was developed for analysis of TIGE in commercial formulations, human plasma and urine. The spectrofluorimetric technique based on the reaction of secondary amine moiety in TIGE with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in slightly alkaline medium producing a highly fluorescent product measured at 540 nm (λex at 470 nm) after heating for 15 min at 75°C. The proposed strategy was upgraded and approved by ICH rules and bio-analytical validated using US-FDA recommendations. A linear relationship between fluorescence intensity and TIGE concentration was observed over the concentration range 40-500 ng mL-1 with limit of quantification (LOQ) 21.09 ng mL-1 and limit of detection (LOD) 6.96 ng mL-1 .The ultra-affectability and high selectivity of the proposed strategy permits analysis of TIGE in dosage form, human plasma and urine samples with good recovery ranged from 97.23% to 98.72% and from 99.36% to 99.80% respectively, without any interfering from matrix components. Also, the developed strategy was used to examine the stability of TIGE in human plasma and applied for pharmacokinetic investigation of TIGE.

A selective spectrophotometric method for determination of rosoxacin antibiotic using sodium nitroprusside as a chromogenic reagent.

A selective spectrophotometric method for the determination of rosoxacin (ROS), a 4-quinolone antimicrobial agent, has been developed and validated. The method was based on the reaction of ROS with alkaline sodium nitroprusside (SNP) reagent at room temperature forming a red colored chromogen measured at 455 nm. The conditions affecting the reaction (SNP concentration, pH, color-developing time, temperature, diluting solvent and chromogen stability time) were optimized. Under the optimum conditions, good linear relationship (r=0.9987) was obtained between the absorbance and the concentration of ROS in the range of 20-50 microg ml(-1). The assay limits of detection and quantitation were 2.5 and 8.4 microg ml(-1), respectively. The method was successfully applied to the analysis of bulk drug and laboratory-prepared tablets; the mean percentage recoveries were 100.1+/-0.33 and 101.24+/-1.28%, respectively. The results were compared favourably with those obtained by the reported method; no significant difference in the accuracy and precision as revealed by the accepted values of t- and F-tests, respectively. The robustness and ruggedness of the method was checked and satisfactory results were obtained. The proposed method was found to be highly selective for ROS among the fluoroquinolone antibiotics. The reaction mechanism was proposed and it proceeded in two steps; the formation of nitroferrocyanide by the action of sodium hydroxide alkalinity on SNP and the subsequent formation of the colored nitrosyl-ROS derivative by the attack at position 6 of ROS.

Generic nonextractive spectrophotometric method for determination of 4-quinolone antibiotics by formation of ion-pair complexes with beta-naphthol.

This paper describes the development of a generic spontaneous nonextractive spectrophotometric method for determination of 13 pharmaceutically important 4-quinolone antibiotics. The method was based on the formation of yellow-colored water-soluble ion-pair complexes between 2% (w/v) beta-naphthol reagent and each of the studied drugs in sulfuric acid medium at room temperature. The formed ion-pair chromogens have maximum absorption peaks in the range of 365-391 nm. The concentrations of the reagents and the experimental conditions affecting the reaction were optimized. Under the optimum conditions, linear relationships with good linear coefficients (0.9987-0.9995) were found between the absorbance and concentration of the investigated drugs in the range of 10-350 microg/mL. The assay limits of detection and quantitation were 1-9.9 and 3.4-32.9 microg/mL, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. The proposed method was successfully applied to the analysis of the investigated drugs in pure and pharmaceutical dosage forms with good accuracy and precision; the percentages of label claim ranged from 97.8-102.8 +/- 0.35-1.60%. The results obtained by the proposed spectrophotometric method were comparable with those obtained by the official or reported methods. The proposed method is superior to all the previously reported ion-pair formation-based methods in terms of simplicity because it did not involve extraction procedures for the ion-pair complex. Therefore, this method might be recommended for routine use in quality control laboratories for analysis of the investigated 4-quinolone antibiotics in their pure forms, as well as in pharmaceutical dosage forms.