Pharma & Specialty Chemical Standards

Cephapirin, a first-generation cephalosporin antibiotic, is systematically named (6R,7R)-7-[(Z)-2-(2-amino-1,3-thiazol-4-yl)-2-methoxyiminoacetyl]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid. Its molecular formula is C16H16N4O5S, with a molecular weight of 372.38 g/mol. Structurally, it features a beta-lactam ring fused to a dihydrothiazine ring, with a methoxyimino-substituted side chain. It exhibits broad-spectrum activity against Gram-positive and some Gram-negative bacteria. Cephapirin is a white to off-white powder, sparingly soluble in water, with a pKa of ~2.8. Its mechanism involves inhibiting bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), disrupting peptidoglycan cross-linking.