Related Experiment Video
Updated: May 20, 2026

A Package of Established Analytical Tools to Investigate the Solid-State Alteration of Lipid-Based Excipients
Published on: August 9, 2022
Thermoanalytical investigation of some sulfone-containing drugs
Nahla N Salama1, Mohammed A El Ries, Safaa Toubar
1Pharmaceutical Chemistry Department, National Organization for Drug Control and Research, Pyramids Avenue, P.O. Box 29, Giza, Egypt.
Abstract:
The thermal behavior of some sulfone-containing drugs, namely, dapsone (DDS), dimethylsulfone (MSM), and topiramate (TOP) in drug substances, and products were investigated using different thermal techniques. These include thermogravimetry (TGA), derivative thermogravimetry (DTG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). The thermogravimetric data allowed the determination of the kinetic parameters: activation energy (E(a)), frequency factor (A), and reaction order (n). The thermal degradation of dapsone and topiramate was followed a first-order kinetic behavior. The calculated data evidenced a zero-order kinetic for dimethylsulfone. The relative thermal stabilities of the studied drugs have been evaluated and follow the order DDS > TOP > MSM. The purity was determined using DSC for the studied compounds, in drug substances and products. The results were in agreement with the recommended pharmacopoeia and manufacturer methods. DSC curves obtained from the tablets suggest compatibility between the drugs, excipients and/or coformulated drugs. The fragmentation pathway of dapsone with mass spectrometry was taken as example, to correlate the thermal decomposition with the resulted MS-EI. The decomposition modes were investigated, and the possible fragmentation pathways were suggested by mass spectrometry.
Related Concept Videos
Preparation and Reactions of Sulfides
Phase II Reactions: Sulfation and Conjugation with α-Amino Acids
Structure and Nomenclature of Thiols and Sulfides
Amines to Sulfonamides: The Hinsberg Test
Generally, a primary amine reacts with the Hinsberg reagent to produce an N-substituted benzenesulfonamide. The electron-withdrawing sulfonyl...
Drug Metabolism: Phase II Reactions
Electrophilic Aromatic Substitution: Sulfonation of Benzene
