Viccillin-SX 1500 Mechanism of Action

Biochemical studies with cell-free bacterial system have shown sulbactam to be an irreversible inhibitor of several important β-lactamases that occur in penicillin-resistant organisms. It possesses significant antibacterial activity only against Neisseriaceae, Acinetobacter calcoaceticus, Bacteroides sp, Branhamella catarrhalis and Pseudomonas cepacia. The potential for sulbactam sodium is 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 β-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.
Viccillin-SX 1500 powder for injection is effective against a wide range of gram-positive and gram-negative bacteria including: Staphylococcus aureus and S. epidermidis (including penicillin-resistant and some methicillin-resistant strains); Streptococcus pneumoniae, Streptococcus faecalis and other Streptococcus spp; Haemophilus influenzae and H. parainfluenzae (both β-lactamase positive and negative strains); Branhamella catarrhalis; anaerobes, including Bacteroides fragilis and related species; Escherichia coli, Klebsiella spp, Proteus spp (both indole-positive and negative), Morganelli morganii, Citrobacter spp, Enterobacter spp, Neisseria meningitidis and Neisseria gonorrhoeae.
Ampicillin/sulbactam 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 ampicillin and sulbactam are achieved in the blood following IV or IM administration and both components have a half-life of approximately 1 hr. Most of the ampicillin/sulbactam is excreted unchanged in the urine.