Sulfamethylphenazole

Sulfamethylphenazole (Sulfapyrazole; Vesulong) is a long-acting sulfonamide antibacterial agent. Sulfamethylphenazole maintains effective chemotherapeutic blood concentrations through the slow release of free sulfonamide from a protein-binding reservoir and can be used in combination with antibiotics such as Terramycin for bovine hemorrhagic septicemia. Sulfamethylphenazole exhibits moderate antimycobacterial activity against Mycobacterium tuberculosis H37Rv (MIC = 15.38 μg/mL) and inhibitory activity against CYP 2C9. Sulfamethylphenazole can be used in studies related to tuberculosis and hemorrhagic septicemia^[1][2][3]. In Vitro:Sulfamethylphenazole (compound 16c) moderately inhibits Mycobacterium tuberculosis H37Rv, with an MIC of 15.38 μg/mL^[1].
Sulfamethylphenazole (0.5 μM) inhibits CYP 2C9 by 45.0%^[1]. In Vivo:Sulfamethylphenazole (20% solution, 10-30 mL/100 kg; intramuscular injection; single administration) shows that in calves, a single intramuscular injection of 20 mL/100 kg is identified as the optimal dose for maintaining long-acting chemotherapeutic plasma concentrations in dairy cows^[2].
In a field survey of hemorrhagic septicemia in cattle/buffaloes in Punjab, Pakistan, Sulfamethylphenazole combined with terramycin is preferred by 60% of veterinarians, while its single use is accepted by 30% of them. Moreover, it is only effective when administered in the early stage of the disease^[3].