Sulfasymazine is a sulfonamide drug and displays antibacterial properties. IC50 & Target: Bacterial^[1] In Vivo: Sulfasymazine is a sulfonamide drug and displays antibacterial properties. On a dosage basis, Sulfasymazine is from 2 to 10 times more potent than sulfisoxazole; on a blood level basis, Sulfasymazine potency ranges from 0.3 to 1. In acute toxicity studies in mice, the sodium salt of Sulfasymazine is tolerated at 2000 mg/kg orally, and at 1000 mg/kg intraperitoneally^[1].