Shereen Shalan

Simultaneous determination of sulpiride and mebeverine by HPLC method using fluorescence detection: application to real human plasma

A new simple, rapid and sensitive reversed-phase liquid chromatographic method was developed and validated for the simultaneous determination of sulpiride (SUL) and mebeverine Hydrochloride (MEB) in the presence of their impurities and degradation products. The separation of these compounds was achieved within 6 min on a 250 mm, 4.6 mm i.d., 5 m particle size Waters®-C18 column using isocractic mobile phase containing a mixture of acetonitrile and 0.01 M dihydrogenphosphate buffer (45:55) at pH = 4.0. The analysis was performed at a flow rate of 1.0 mL/min with fluorescence-detection at excitation 300 nm and emission at 365 nm. The concentration-response relationship was linear over a concentration range of 10- 100 ng/mL for both MEB and SUL with a limit of detection 0.73 ng/mL and 0.85 ng/mL for MEB and SUL respectively. The proposed method was successfully applied for the analysis of both MEB and SUL in bulk with average recoveries of 100.22 ± 0.757% and 99.96 ± 0.625% respectively, and in commercial tablets with average recoveries of 100.04 ± 0.93% and 100.03 ± 0.376% for MEB and SUL respectively. The proposed method was successfully applied to the determination of MEB metabolite (veratic acid) in real plasma simultaneously with SUL. The mean% recoveries (n = 3) for both MEB metabolite (veratic acid) and SUL were 100.36 ± 2.92 and 99.06 ± 2.11 for spiked human plasma respectively. For real human plasma, the mean% recoveries (n = 3) were and respectively.

Determination of tizoxanide, the active metabolite of nitazoxanide, by micellar liquid chromatography using a monolithic column. Application to pharmacokinetic studies

In this study, a micellar liquid chromatography (MLC) method is proposed for the determination of tizoxanide (TZ), the active metabolite of nitazoxanide (NX), using a micellar mobile phase consisting of 0.1 M sodium dodecyl sulphate, 8% n-propanol and 0.3% triethylamine in 0.02 M phosphoric acid buffered at pH 4. The method was successfully applied to the analysis of tizoxanide (TZ), the active metabolite of nitazoxanide (NX), in the presence of tinidazole (TIN) as an internal standard in the pure form, in real human urine and plasma without a previous extraction step. Analytical separation was performed in less than 10 min using a RP C18 monolithic column with UV detection at 240 nm. The validation study of the proposed method was successfully carried out in an assay range between 0.05 and 20 μg mL−1 with the limit of detection (LOD) 0.016 μg mL−1 and the limit of quantification (LOQ) 0.049 μg mL−1. The method was fully validated in accordance with the ICH guidelines. The proposed method was successfully applied to quantitatively determine TZ in spiked human urine and plasma. It was also extended to the pharmacokinetic studies of TZ in real human urine and plasma samples.

Micellar High Performance Liquid Chromatographic Method forSimultaneous Determination of Clonazepam and Paroxetine HCl inPharmaceutical Preparations Using Monolithic Column

A new and accurate micellar high performance liquid chromatographic method coupled with ultraviolet detection was developed for simultaneous determination of Clonazepam (CLZ) and Paroxetine (PRX) using a monolithic C-18 column, and mobile phase consisting of 0.175M Sodium dodecyl sulphate, 12% n-propanol prepared in 0.02M phosphoric acid at pH 6.0. The analysis was performed at a flow rate of 1 mL/min with ultraviolet- detection at 300 nm. The method was linear over the concentration range (1.0-20 μg) and (4.0-250 μg) with limits of detection of 0.277, 2.675 μg/mL and limits of quantification of 0.838, 8.106 μg/mL for CLZ and PRX respectively. The average % recovery was found to be 100.08 ± 1.31 and 100.22 ± 1.15 for CLZ and PRX respectively. Method validation according to ICH Guidelines recommendation was evaluated. Statistical analysis of the results obtained by the proposed method was compared successfully with those obtained using the reference one. There was no significance difference between the two methods regarding accuracy and precision respectively.

Validated spectrofluorimetric method for the determination of clonazepam in pharmaceutical preparations

A simple, highly sensitive and validated spectrofluorimetric method was applied in the determination of clonazepam (CLZ). The method is based on reduction of the nitro group of clonazepam with zinc/CaCl2, and the product is then reacted with 2-cyanoacetamide (2-CNA) in the presence of ammonia (25%) yielding a highly fluorescent product. The produced fluorophore exhibits strong fluorescence intensity at ʎ(em) = 383 nm after excitation at ʎ(ex) = 333 nm. The method was rectilinear over a concentration range of 0.1-0.5 ng/mL with a limit of detection (LOD) of 0.0057 ng/mL and a limit of quantification (LOQ) of 0.017 ng/mL. The method was fully validated and successfully applied to the determination of CLZ in its tablets with a mean percentage recovery of 100.10 ± 0.75%. Method validation according to ICH Guidelines was evaluated. Statistical analysis of the results obtained using the proposed method was successfully compared with those obtained using a reference method, and there was no significance difference between the two methods in terms of accuracy and precision.

First derivative spectrofluorimetric determination of zopiclone and its degradation product, 2-amino-5-chloropyridine, in pharmaceutical formulations with preliminary tool in biological fluids for clinical evidence of zopiclone intake

A simple, fast, sensitive and stability-indicating derivative spectrofluorimetric method is presented for the assay of zopiclone (ZOP), a drug with hypnotic effect, and its main degradation product and major contaminant, 2-amino-5-chloropyridine (ACP). The method is based on measuring the inherent fluorescence intensity of both drugs at λex=300nm in methanol, then differentiation using D1 (first derivative technique). The developed method was found to be rectilinear over a range of 0.2-4μg/mL of ZOP and 4-100ng/mL of ACP. The limits of detection were 0.05μg/mL of ZOP and 0.2ng/mL of ACP with the limit of quantitation of 0.17μg/mL of ZOP and 0.7ng/mL of ACP. The outcoming results of the proposed method were compared to those obtained by a reference method showing no significant statistical difference between them concerning precision and accuracy. Additionally, the developed method was applied for detecting ACP in spiked human urine and plasma specimens as a tool of clinical evidence of zopiclone intake that can be easily implemented in forensic laboratories. The proposed method was validated as per ICH guidelines.