Azidocillin is a narrow-spectrum, semisynthetic penicillin derivative with antibacterial activity towards Grain-positive and Gram-negative microorganisms, including Haemophilus influenze, against which it is as effective as ampicillin. Azidocillin binds to and inactivates penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. Inactivation of PBPs interferes with the cross-linkage of peptidoglycan chains necessary for bacterial cell wall strength and rigidity. This interrupts bacterial cell wall synthesis and results in the weakening of the bacterial cell wall, eventually causing cell lysis. Azidocillin can be applied in the treatment of inflammation of upper airways, middle ear, sinuses, throat, larynx and palatine tonsils. The substance is excreted with urine in 50-70% in the unchan¬ged form. It binds to the blood plasma proteins in 84%, and its half-life period is 30 min. The side effects are similar as those of benzylpenicillin but occur less frequently.