Comparative experimental antibacterial activity of ceftriaxone (Ro 13-9904).

The in vitro activity of new cephalosporins, oxacephems and penicillins against pathogens involved in respiratory and gastrointestinal tract infections is practically equivalent. However, in experimental infections with the same pathogens the superior efficacy of ceftriaxone over all comparative cephems and penicillins, expressed in low 50% effective doses after multiple and particularly after single dosage schedules, and caused by a longer maintenance of blood and tissue levels can be demonstrated. Although mice have an altered pharmacokinetics these experimental results reflect the observed clinical advantage of ceftriaxone in human infections: long plasma half-life, low dosage and single daily administration.