Mohammed, M. A. - A., M. A. Fouad, A. Mohammed aboelyazed, A. M. Yehia, and S. T. Mahmoud, A validated and environmentally sustainable high-performance thin-layer chromatography method for the concurrent analysis of axitinib, pazopanib, crizotinib, ruxolitinib, and ibrutinib in bulk drug substances and pharmaceutical formulations, , 2025. AbstractWebsite

A simple, precise, environmentally friendly, and selective high-performance thin-layer chromatography (HPTLC) method has been developed and validated for the simultaneous quantification of axitinib, pazopanib hydrochloride, crizotinib, ruxolitinib, and ibrutinib in bulk and pharmaceutical dosage forms. These five anticancer drugs are commonly utilized in the treatment of various malignancies and have demonstrated superior efficacy when used in combination therapies compared with monotherapy. This allows for dosage reduction and, consequently, a decrease in toxicity. The drugs were effectively separated on silica gel HPTLC plates (G60 F254) using a mobile phase comprising methanol–0.1% formic acid (65:35, V/V), with ultraviolet (UV) detection at 268 nm under ambient conditions. Experimental parameters were optimized, yielding linearity ranges of 5–50 µg per band for axitinib and pazopanib; 10–60 µg per band for ruxolitinib and ibrutinib; and 10–50 µg per band for crizotinib, demonstrating high sensitivity and low limits of detection: 0.052, 0.066, 0.111, 0.093, and 0.038 µg per band for axitinib, pazopanib, ruxolitinib, ibrutinib, and crizotinib, respectively. The method was successfully applied to the separation of these drugs in both bulk and dosage forms, yielding high recovery rates, which confirm the efficiency of the approach. Additionally, the greenness of the method was evaluated using the Eco-Scale Assessment (ESA), Green Analytical Procedure Index (GAPI), and Analytical Greenness Metric (AGREE) metrics, all of which confirmed its environmentally sustainable profile.

Mohamed, H. A. - H., M. B. NourEldin, A. A. El-Zaher, and S. T. Mahmoud, Development of an eco-friendly UPLC method for simultaneous quantification of six selected phosphodiesterase-5 inhibitors and serotonin reuptake inhibitors in pharmaceutical formulations and adulterated food using a quality by design approach, , vol. 11, issue 1, pp. 69, 2025. AbstractWebsite

This study introduces an innovative, environmentally sustainable ultra-performance liquid chromatography (UPLC) method with UV detection for the concurrent quantification of six clinically relevant pharmaceuticals—vardenafil, avanafil, sildenafil, dapoxetine, duloxetine, and tadalafil—frequently employed in the management of erectile dysfunction and premature ejaculation. This study employs quality by design (QbD) concepts to optimize chromatographic settings, assuring good selectivity, precision, and resilience, while conforming to green analytical chemistry standards, in contrast to previously published approaches. A face-centered composite design was utilized to systematically optimize critical parameters, resulting in effective separation using a reversed-phase C18 column, an acetate buffer (pH 3), and a mobile phase composed of buffer and methanol (72.5:27.5, v/v) at a flow rate of 0.5 mL/min. The new approach exhibited significant sensitivity and robustness in pharmaceutical dosage forms and contaminated food samples, especially in identifying illicit sildenafil and tadalafil adulteration in honey-based products. The proposed approach was thoroughly validated in accordance with ICH principles, satisfying analytical performance criteria for linearity, precision, accuracy, and robustness. The method's environmental impact was assessed using AGREE metrics, validating its adherence to green analytical chemistry standards. This approach, characterized by its swift analysis time, low solvent usage, and exceptional separation efficiency, serves as a significant analytical instrument for quality control laboratories, pharmaceutical analysis, and food safety monitoring.

Elsayad, K. A., G. F. Elmasry, S. T. Mahmoud, F. M. Awadallah, S. Giovannuzzi, and C. T. Supuran, "Development of novel amino-benzenesulfonamide derivatives and their analogues as carbonic anhydrase inhibitors: Design, synthesis, anticancer activity assessment, and pharmacokinetic studies using UPLC-MS/MS", Bioorganic Chemistry, vol. 159, pp. 108335, 2025. AbstractWebsite

The present study outlines the design and synthesis of dual-tail analogues of SLC-0111 as carbonic anhydrase inhibitors (CAIs) targeting tumor isoforms IX and XII 4a-h and 5a-h, along with pharmacokinetic studies. The synthesized compounds were evaluated for their inhibitory activity against four carbonic anhydrase isoforms (hCA I, II, IX, and XII), revealing potent activity, particularly against hCA IX and XII. Notably, compounds 4b, 5a, and 5b demonstrated strong inhibition of hCA IX with Ki values of 20.4, 12.9, and 18.2 nM, respectively, compared to acetazolamide (AAZ), which has a Ki of 25 nM. Additionally, compounds 5a, 5b, 5c, and 5d showed selective inhibition of hCA XII, with Ki values of 26.6, 8.7, 17.2, and 10.9 nM, respectively, relative to AAZ (Ki = 5.7 nM). Moreover, both series were tested for their anti-proliferative activity following the US-NCI protocol against a panel of more than fifty cancer cell lines. Compound 5h met the activity criteria and was automatically scheduled for further evaluation at five concentrations with 10-fold dilutions, revealing high toxicity toward leukemia and lower toxicity against melanoma. In addition, the MTT cytotoxicity assay was performed on 5f, 5d and acetazolamide using WI-38 cells. Furthermore, an in vivo pharmacokinetic study was conducted using UPLC-MS/MS on the most potent derivative, 5d, demonstrating a comparable pharmacokinetic profile compared to the reference drug acetazolamide. Furthermore, molecular docking prediction studies were conducted for the most active compounds, 5d and 5h, to elucidate their interactions with the active site hot spots of the CA isoform.

Sayed, R. M., S. T. Mahmoud, E. A. Mostafa, M. K. El-Ashrey, and M. A. Moffid, "Insights Into the Complexities of Antithrombotic Interactions: A Core–Shell Particle-Based UHPLC–MS/MS Method to Investigate Dexamethasone's Influence on Apixaban and Rivaroxaban Pharmacokinetics", SEPARATION SCIENCE PLUS, vol. 8, no. 2, pp. e70009, 2025. AbstractWebsite

ABSTRACT The implementation of core–shell particles in HPLC has many advantages in analytical methodologies, including enhancement of sensitivity and resolution. Moreover, high flow rates and short analysis times could be used to achieve efficient separations. A sensitive and specific UHPLC–MS/MS method was developed and validated for the simultaneous quantification of apixaban (APX) and rivaroxaban (RVX) in rat plasma. This validated method was designed to investigate the potential pharmacokinetic (PK) interactions between dexamethasone (DEX) and both cited drugs in rat model. Separation and validation were performed utilizing a C18 Poroshell 120EC (50 mm × 4.6 mm, 2.7 µm) column with a mobile phase of methanol:water with 0.1% formic acid (95:5, v/v) eluted in an isocratic mode at 0.3 mL/min flow rate. Liquid–liquid extraction method was employed to extract the cited drugs from rat plasma using diethyl ether:dichloromethane (70:30, v/v). The procedure was carried out utilizing positive ionization and multiple reaction monitoring mode (MRM) for the detection of the drugs and the internal standard, moxifloxacin. The bioanalytical method was validated using US-Food and Drug Administration and European Medicines Agency guidelines in terms of selectivity, linearity, accuracy, precision, recovery, dilution integrity, matrix effect, stability, and carryover. On the basis of the findings of the PK study in rat model, a potential drug–drug interaction was observed between DDI and the cited antithrombotic medications that may lead to a decrease in their plasma concentrations. As a result, these findings can be utilized for further clinical investigation.

Ahmed, M. H., E. F. Elkady, S. T. Mahmoud, and E. H. Mohamed, "A green validated HPLC-UV Method for determining and quantifying pholcodine, paracetamol, and pseudoephedrine in laboratory-prepared mixtures and their FDC capsule", Green Analytical Chemistry, vol. 12, pp. 100187, 2025. AbstractWebsite

A validated technique has been developed for the sequential determination of pholcodine, paracetamol, and pseudoephedrine. This method allows for their separation either in different ratios within a ternary mixture or in their fixed-dose combination (FDC) using HPLC. The chromatographic conditions involved the utilization of an X-select C18 column (5µ, 4.6 × 150 mm) and a mobile phase consisting of 0.05 M KH2PO4: Methanol (75:25, v/v), with orthophosphoric acid added to adjust the pH to 2.6. The separation was conducted at a 1.2 ml/min flow rate, while a UV detector was set at a wavelength of 206 nm to monitor the process. The three drugs were successfully eluted with retention times of 0.8, 1.9, and 3.0 min for pholcodine, paracetamol, and pseudoephedrine respectively providing fast analysis times. The method exhibited linearity for pholcodine, paracetamol, and pseudoephedrine over concentration ranges of 12–200 µg/ml, 5–100 µg/ml, and 30–200 µg/ml, respectively. It was accurate, reliable, and precise (RSD < 2 %). This proposed methodology was effectively implemented to quantify the concentration of pholcodine, pseudoephedrine, and paracetamol in freshly prepared mixtures and pharmaceutical dosage forms. Furthermore, the method's environmental impact was assessed using five different tools, demonstrating low hazard levels to the environment, and promoting its environmental friendliness compared to the reported method.

Ghanem, H. N., A. A. El-Zaher, S. T. Mahmoud, and E. A. Taha, Spectrophotometric determination of olanzapine, fluoxetine HCL and its impurity using univariate and chemometrics methods reinforced by latin hypercube sampling: Validation and eco-friendliness assessments, , vol. 18, issue 1, pp. 201, 2024. AbstractWebsite

Novel univariate and chemometrics-aided UV spectrophotometric methods were tailored to undergo the fundamentals of green and white analytical chemistry for the simultaneous estimation of a ternary mixture of olanzapine (OLA), fluoxetine HCL (FLU), and its toxic impurity 4-(Trifluoromethyl) phenol (FMP) without any prior separation. The dual-wavelength ratio spectrum univariate method was used to determine OLA and FLU in the presence of FMP in the range of (4–20) and (5–50) μg/ml, respectively. In compliance with the International Conference on Harmonization (ICH) standards, the technique was validated and established Remarkable accuracy (98–102%) and precision (< 2%) with limits of quantification (LOQs) of 0.432 and 2.002 μg/ml, respectively. Partial least squares (PLS) and artificial neural networks (ANNs) are chemometric methodologies that have advantages over the univariate method and use significant innovations employing Latin hypercube sampling (LHS), allowing the generation of a reliable validation set to guarantee the effectiveness and sustainability of these models. The concentration ranges used were (2–20), (2–20), and (5–50) μg/ml; for PLS, the LOQs were 0.602, 0.508, and 1.429 μg/ml, and the root mean square errors of prediction (RMSEPs) were 0.087, 0.048, and 0.159 for OLA, FMP, and FLU, respectively; and for ANNs, the LOQs were 0.551, 0.465, and 0.965 μg/ml, with RMSEPs of 0.056, 0.047, and 0.087 for OLA, FMP, and FLU, respectively. The developed methods yield a greener National Environmental Methods Index (NEMI) with an eco-scale assessment (ESA) score of 90 and a complementary Green Analytical Procedure Index (complex GAPI) in quadrants with an analytical greenness metric (AGREE) score of 0.8. The Red‒Green–Blue 12 algorithm (RGB 12) scored 88.9, outperforming on reported methods and demonstrating widespread practical and environmental approval. Statistical analysis revealed no noteworthy differences (P > 0.05) among the proposed and published techniques. Both pure powders and pharmaceutical capsules were analyzed via these methods.

Abdelhafeez, H., A. El-Zaher, O. Ahmed-Farid, badawimohamed, and S. Tarek, "Proper retention factor for Avanafil and Dapoxetine Hydrochloride Separation and Validation with RP-HPLC in Bulk, Dosage Form and Rat Plasma; Validation, Degradation, and Pharmacokinetic Application", Egyptian Journal of Chemistry, vol. 67, no. 12: National Information and Documentation Centre (NIDOC), Academy of Scientific Research and Technology, ASRT, pp. 37-46, 2024. AbstractWebsite

Environmental changes and fluctuated storage conditions are the main markers for API degradation and drug-drug interactions. Avanafil (Ava), phosphodiesterase inhibitor and dapoxetine (Dap), selective serotonin reuptake inhibitor helps to treat erectile dysfunction and increase ejaculation retention. The aim of the current study is to investigate the best chromatographic condition for the determination of Ava, Dap and their degradation products at different stress conditions and develop a sensitive, rapid, and reproducible method for their simultaneous estimation either in their combined dosage form or in rat plasma. The chromatographic conditions involve separation with RP-Eclipse-XDP C18 column, (25 cm ×4.6 mm, 5µ) column at 239 nm detection wavelength and mobile phase consisting of buffer (phosphate, pH 3) to acetonitrile with ratio 55:45 (v/v) and the injection volume was 20 µl. The method was subsequently used to evaluate the mixture of Ava and Dap pharmacokinetics in rat plasma. The pharmacokinetic parameters Cmax, Tmax, t1/2, AUC0- 24, AUCtotal, Ke, Vd, and CL of the cited drugs after oral administration was determined. The obtained data demonstrate that the method was applied successfully for separating each component and their degradation products with all accepted validation parameters and the method can be applied for preclinical pharmacokinetic investigation.

Elsayad, K. A., G. F. Elmasry, S. T. Mahmoud, and F. M. Awadallah, "Sulfonamides as anticancer agents: A brief review on sulfonamide derivatives as inhibitors of various proteins overexpressed in cancer", Bioorganic Chemistry, vol. 147, pp. 107409, 2024.
Ahmed, M. H., E. F. Elkady, S. T. Mahmoud, and E. H. Mohamed, "Two green UV-spectrophotometric techniques applying successive and progressive resolution with new concepts for simultaneous determination of completely overlapping ternary mixture", Analytical Chemistry Letters, vol. 14, issue 2, pp. 190-208, 2024.
Saleh, O. A., A. M. Badawey, H. A. Y. Enein, and S. T. Mahmoud, "An innovative combination of molecular modeling and green analysis approaches for the enantioseparation and quantitation of certain CNS acting drugs using HPLC", Microchemical Journal, vol. 200, pp. 110498, 2024.
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