Pharmacology: Pharmacodynamics: Biochemical studies with cell-free bacterial systems have shown sulbactam to be an irreversible inhibitor of most important beta-lactamases that occur in penicillin-resistant organisms. While sulbactam's antibacterial activity is mainly limited to Neisseriaceae, the potential for sulbactam sodium in preventing the destruction of penicillins and cephalosporins by resistant organisms was confirmed in whole-organism studies using resistant strains, in which sulbactam sodium exhibited marked synergistic effects with penicillins and cephalosporins. Since sulbactam also binds to some penicillin-binding proteins, some sensitive strains are rendered more susceptible to the combination than to the beta-lactam antibiotic alone.
The bactericidal component of the combination is ampicillin which, like benzyl penicillin, acts against sensitive organisms during the stage of active multiplication by the inhibition of biosynthesis of cell-wall mucopeptide.
Sulbactam sodium/ampicillin sodium IM/IV is effective against a wide range of Gram-positive and Gram-negative bacteria including: Staphylococcus aureus and epidermidis (including penicillin-resistant and some methicillin-resistant strains); Streptococcus pneumoniae, Streptococcus faecalis and other Streptococcus species; Haemophilus influenzae and parainfluenzae (both beta-lactamase positive and negative strains); Branhamella catarrhalis, anaerobes, including Bacteroides fragilis and related species; Escherichia coli, Klebsiella species, Proteus species (both indole-positive and indole-negative), Morganelli morganii, Citrobacter species, Enterobacter species, Neisseria meningitides and Neisseria gonorrhoeae.
Pharmacokinetics: Sulbactam sodium/ampicillin sodium IM/IV diffuses readily into most body tissues and fluids in the human. Penetration into brain and spinal fluid is low except when meninges are inflamed. High concentrations of sulbactam and ampicillin are achieved in the blood following intravenous or intramuscular administration and both components have a half life of approximately 1 hour. Most of the sulbactam sodium/ampicillin sodium IM/IV is excreted unchanged in the urine.