Multiclass analysis on repaglinide,flubendazole, robenidine hydrochloride and danofloxacin drugs |
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Authors: | Taleb T. Al-Nahary Mohamed Abdel Nabi El-Ries Gehad G. Mohamed Ali Kamal Attia Yahia Nasser Mabkhot Michelyne Haroun Assem Barakat |
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Affiliation: | 1. Department of Chemistry, Faculty of Applied Science, Thamar University, P.O. Box 87246, Yemen;2. National Organization for Drug Control and Research, 6-Abu Hazem St., Pyramide, P.O. Box 29, Cairo, Egypt;3. Chemistry Department, Faculty of Science, Cairo University, P.O. Box 12613, Giza, Egypt;4. Department of Chemistry, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia;5. Department of Pharmaceutical, College of Pharmacy, Umm Al-Qura University, Makkah, Saudi Arabia |
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Abstract: | The drugs under study; repaglinide (Repag), flubendazole (Flu), robenidine hydrochloride (Roben) and danofloxacin (Dano) are antidiabetic, anthelmintic, anticoccidial, and antibiotic drugs. In the present study, they are investigated using electron impact mass spectral (EI-MS) fragmentation at 70 eV, in comparison with thermal analyses measurements (TGA/DrTGA and DTA) and molecular orbital calculation (MO). Semi-empirical MO calculation, AM1 procedure, has been carried out on Repag, Flu, Roben and Dano both as neutral molecules (in TA) and the corresponding positively charged species (in MS). The calculated MO parameters include bond length, bond order, charge distribution on different atoms and heat of formation. The fragmentation pathways of Repag, Flu, Roben and Dano in EI-MS led to the formation of important primary and secondary fragment ions. The mechanism of formation of some important daughter ions can be illuminated from comparing with that obtained using mass spectrometer through the accurate mass measurement determination. The MO provides a base for fine distinction among sites of initial bond cleavage and subsequent fragmentation of drug molecules in both thermal analysis and MS techniques. The activation thermodynamic parameters, such as, (activation energy E1), (enthalpy ΔH1), (entropy ΔS1) and (Gibbs free energy ΔG1) are calculated from the DrTGA curves using Coats–Redfern and Horowitz–Mitzger methods. |
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Keywords: | Repag Flu Roben and Dano EI-MS spectrometry Thermal analyses Molecular orbital calculation (MOC) |
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