Jenny Jeehan Nasr

Stability‐Indicating HPLC Method for the Determination of Quetiapine: Application to Tablets and Human Plasma

Abstract A stability‐indicating reversed‐phase high performance liquid chromatographic method was developed for the analysis of the antipsychotic drug quetiapine. Quetiapine was determined in presence of two of its degradation products; quetiapine N‐oxide and quetiapine lactam. The analysis was carried out using a 250 mm×4.6 mm i.d., 5 µm particle size Zorbax SB‐Phenyl column. Mobile phase containing a mixture of acetonitrile and 0.02 M phosphate buffer (50∶50) at pH=5.5 was pumped at a flow rate of 1 mL/min with UV detection at 254 nm. The method showed good linearity in the range of 0.08–20 µg/mL with limit of detection (S/N=3) 0.03 µg/mL (3.3×10−8 M). The suggested method was successfully applied for the analysis of quetiapine in bulk, tablets, and human plasma with average recoveries of 99.96±1.25%, 101.37±0.481%, and 100.82±1.53%, respectively. The proposed method was also applied for the determination of quetiapine in the presence of some co‐administered drugs as clomipramine, carbamazepine, and fluconazole.

Direct determination of ampicillin and amoxicillin residues in food samples after aqueous SDS extraction by micellar liquid chromatography with UV detection

A simple, sensitive and rapid micellar HPLC method was optimized and validated for the analysis of amoxicillin and ampicillin residues in food samples. Analytical separation was performed in less than 7 min using a RP C18 column with UV detection at 220 nm and a micellar solution of 0.05 M sodium dodecyl sulphate, 5% 1-propanol and 0.3% triethylamine in 0.02 M phosphoric acid buffered at pH 5 as the mobile phase. The flow rate was 1 mL min−1 and the effluent was monitored at 220 nm. The micellar method was successfully applied to quantitatively determine amoxicillin and ampicillin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, kidney and eggs. The method was fully validated in accordance with ICH guidelines. Linearity was in the range 0.4–20 μg mL−1 for each drug and the percentage recoveries of both drugs ranged from 95.5 to 102.3% for amoxicillin and 95.6 to 101.7% for ampicillin. High extraction efficiency of amoxicillin and ampicillin was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. An aqueous solution of SDS surfactant only was used in extraction. No organic solvent was used during the pretreatment step. Hence, it is considered an interesting technique for “green” chemistry.

Simultaneous determination of zopiclone and its degradation product and main impurity (2-amino-5-chloropyridine) by micellar liquid chromatography with time-programmed fluorescence detection: Preliminary investigation for biological monitoring

A simple and reliable HPLC method was developed and validated for the simultaneous determination of the hypnotic drug, zopiclone (ZPC) and its degradation product and main impurity, 2-amino-5-chloropyridine (ACP). The analyses were carried out on BDS Hypersil phenyl column (4.6 mm × 250 mm, 5 μm particle size) using micellar mobile phase consisting of 0.15M SDS, 10% n-propanol, 0.3% triethylamine, and 0.02 M orthophosphoric acid (pH 3.5) with timed programmable fluorescence detection. The proposed method was found to be rectilinear over the concentration ranges of 0.5-10.0 μg/mL for ZPC and 2.5-50 ng/mL for ACP. Moreover, the method was applied for the determination of ZPC in commercial tablets with mean percentage recovery of 99.06±1.49. The results of the proposed method were statistically compared with those obtained by the comparison method revealing no significance differences in the performance of the two methods regarding accuracy and precision. Furthermore, the proposed method was applied for the detection and determination of ACP in human urine as a marker for ZPC intake.

Stability-Indicating Micellar Liquid Chromatographic Method for the Determination of Clopidogrel. Application to Tablets and Content Uniformity Testing

Abstract A simple, stability-indicating, reversed-phase micellar liquid chromatographic method was developed for the analysis of the antiplatelet drug clopidogrel. Clopidogrel was determined in presence of its carboxylic acid degradation product, namely; SR26334. The analysis was carried out using a 150 mm × 4.6 mm i.d., 5 µm particle size Nucleodur MN-C18 column. The Mobile phase used was a solution containing 0.15 M sodium dodecyl sulphate and 10% n-propanol and 0.3% triethylamine in 0.02 M phosphoric acid at pH = 3.0 pumped at a flow rate of 1 mL/min with UV-detection at 235 nm. The method showed good linearity in the range of 1-20 µg/mL with limit of detection (S/N = 3) 0.06 µg/mL (1.86 × 10−7 M). The suggested method was successfully applied for the analysis of clopidogrel in bulk and in commercial tablets with average recoveries of 99.67% ± 0.94%, and 100.27 ± 0.89%, respectively. The results were favorably compared to those obtained by a reference method. The proposed method was successfully applied to the content uniformity testing of tablets. The proposed method was also applied for the determination of clopidogrel in the presence of its co-administered drug, acetyl salicylic acid, with application to synthetic mixtures and prepared tablets.

Fourth‐derivative synchronous spectrofluorimetry and HPLC with fluorescence detection as two analytical techniques for the simultaneous determination of itopride and domperidone

Two simple, rapid and sensitive methods, namely, fourth-derivative synchronous spectrofluorimetry (method I) and HPLC with fluorescence detection (method II) were developed for the simultaneous analysis of a binary mixture of itopride HCl (ITP) and domperidone (DOM) without prior separation. The first method was based on measuring the fourth derivative of the synchronous fluorescence spectra of the two drugs at Δλ = 40 nm in methanol. The different experimental parameters affecting the synchronous fluorescence of the studied drugs were carefully optimized. Chromatographic separation was performed in < 6.0 min using a RP C18 column (250 mm × 4.6 mm i.d., 5 µm particle size) with fluorescence detection at 344 nm after excitation at 285 nm. A mobile phase composed of a mixture of 0.02 M phosphate buffer with acetonitrile in a ratio of 55 : 45, pH 4.5, was used at a flow rate of 1 mL/min. Linearity ranges were found to be 0.1-2 µg/mL for ITP in both methods, whereas those for DOM were found to be 0.08-2 and 0.05-1.5 µg/mL in methods I and II, respectively. The proposed methods were successfully applied for the determination of the studied drugs in synthetic mixtures and laboratory-prepared tablets.

Determination of six anti-Parkinson drugs using cyclodextrin-capillary electrophoresis method: application to pharmaceutical dosage forms

A novel capillary electrophoretic method was developed for the assay of two quaternary anti-Parkinson mixtures, entacapone, levodopa, carbidopa, and benserazide (mixture I), and selegiline, levodopa, carbidopa, and benserazide (mixture II), by using α-methyldopa as an internal standard. Furthermore, the method was extended for the determination of another anti-Parkinson drug, lisuride, as well as a psychoactive antihypertensive drug, α-methyldopa, without any modification of the general method. Separation and analyses of all compounds were simply achieved in an untreated fused-silica capillary tube (42.0 cm effective length and 50 μm internal diameter) within 7 minutes under an applied voltage of 20 kV. Optimum separation and analyses were obtained using 25 mM borate buffer (pH 9.5) containing 5 mM β-cyclodextrin as the background electrolyte. The apparatus was equipped with a diode array detector (DAD) to identify lisuride at 240 nm and all other drugs at 200 nm. The addition of 5 mM β-cyclodextrin to the borate buffer has a significant effect on the separation of entacapone and benserazide in mixture I, and on the separation of selegiline and benserazide in mixture II, which cannot be achieved without it. The proposed method was successfully applied to analyse the studied drugs in their multi-component and single-component pharmaceutical dosage forms. The analytical results proved the linearity (r2 ≥ 0.9997), accuracy, precision (% RSD < 2), and selectivity of the proposed capillary electrophoretic method.

Stability-Indicating Spectrophotometric Determination of AceclofenacUsing Multivariate Calibration

Two simple, rapid and inexpensive chemometric spectrophtometric methods were established for the stabilityindicating determination of aceclofenac in presence of its degradation product; diclofenac. The applied chemometric techniques are multivariate methods including partial least squares (PLS) and concentration residual augmented classical least squares (CRACLS).The UV absorption spectra of the standard solutions of the training and validation sets in phosphate buffer of pH 6 were recorded in the range of 220-330 nm at 1.0 nm intervals. The developed methods were validated and successfully applied to the analysis of aceclofenac in pharmaceutical dosage forms and in bulk powder. The assay results obtained using the chemometric methods were statistically compared to those of a reference HPLC (high performance liquid chromatographic) method and a good agreement was observed.

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.

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.