Influence of e-beam irradiation on sulfamethoxazole in solid state

Area of Science:

• Pharmaceutical Chemistry
• Radiation Chemistry
• Solid-State Chemistry

Background:

• Sulfamethoxazole (SMX) is a widely used antibiotic.
• Understanding the stability of pharmaceuticals under irradiation is crucial for storage and sterilization.
• Ionizing radiation effects on solid-state drugs require detailed investigation.

Purpose of the Study:

• To investigate the physico-chemical effects of electron beam irradiation on solid sulfamethoxazole.
• To determine the dose-dependent changes in SMX properties.
• To identify radiodegradation products and elucidate the radiolysis mechanism.

Main Methods:

• Solid-state sulfamethoxazole was irradiated with electron beams at doses from 25-800 kGy.
• Spectroscopic methods (UV, IR, MS, EPR) were employed for analysis.
• Chromatographic (TLC, HPLC) and thermal (DSC, XRD) techniques, along with SEM, were used to evaluate changes.

Main Results:

• Color change from white to pale cream observed even at the lowest dose (25 kGy), intensifying with higher doses.
• Radiodegradation products and decreased drug content detected at 400 kGy.
• Free radical trapping in the crystal lattice (1.04 × 10^15 spin/g) is proposed as the cause of color, with S-N and N-C bond cleavage identified as the primary radiolysis pathways.

Conclusions:

• Electron beam irradiation significantly alters the physico-chemical properties of solid sulfamethoxazole.
• Radiolysis leads to the formation of sulfanilamide and sulfanilic acid, with distinct radiolytic yields.
• The study provides insights into the solid-state radiolysis mechanism of SMX.