A dose of CAYSTON consists of a 2 mL amber glass vial containing lyophilized aztreonam (75 mg) and lysine (46.7 mg), and a low-density polyethylene ampule containing 1 mL sterile diluent (0.17% sodium chloride).  The reconstituted solution is for inhalation. The formulation contains no preservatives or arginine.   

AZACTAMŽ (aztreonam for injection, USP) contains the active ingredient aztreonam, a monobactam. It was originally isolated from Chromobacterium violaceum. It is a synthetic bactericidal antibiotic.