Cefonicid (free base) is a second-generation cephalosporin administered intravenously or intramuscularly. Its bactericidal action results from inhibition of cell wall synthesis. It is used for urinary tract infections, lower respiratory tract infections, and soft tissue and bone infections.

Cefonicid monosodium is the salt form of Cefonicid (free base), a second-generation cephalosporin administered intravenously or intramuscularly. Its bactericidal action results from inhibition of cell wall synthesis. It is used for urinary tract infections, lower respiratory tract infections, and soft tissue and bone infections.

Cefonicid binds to and inactivates penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. Cefonicid sodium (Monocid sodium) is the sodium salt form of cefonicid, a semisynthetic second-generation cephalosporin with antibacterial activity. PBPs are enzymes involved in the terminal stages of assembling the bacterial cell wall and in reshaping the cell wall during growth and division. Inactivation of PBPs interferes with the cross-linkage of peptidoglycan chains necessary for bacterial cell wall strength and rigidity. This results in the weakening of the bacterial cell wall and causes cell lysis.