SULFAGUANIDINE MONOHYDRATE is a sulfonamide antibiotic that works by inhibiting bacterial growth and is used to treat or prevent infections in multiple parts of the body. However, this drug is ineffective against colds, influenza, or other viral infections. Sulfonamides inhibit dihydrofolate synthesis by inhibiting dihydropterin synthase. Sulfonamides are competitive inhibitors of bacterial para-aminobenzoic acid (PABA; essential for folate synthesis in bacteria). It is an inhibitor of dihydrofolate reductase (DHFR). It standards are used for bioassays, determination of the content or potency of antibiotics or biochemical drugs. It can also be used as a calibrator for equipment, a substance for evaluating measurement methods, a substance for assigning values to test drugs, and for identifying, inspecting, determining content, and calibrating the performance of testing instruments.