Pharmacodynamic properties
Benethamine benzylpenicillin is the N-benzyl-2phenylethylamine salt of benzylpenicillin, designed as a long-acting formulation of benzylpenicillin. Penethamate is a prodrug from which benzylpenicillin and diethylaminoethanol are released by hydrolysis. Antimicrobial activity is derived exclusively from benzylpenicillin.
The free benzylpenicillin is effective chiefly against a variety of Gram-positive pathogens, excluding β-lactamase producing staphylococci. Penicillins act bactericidally on proliferating micro-organisms by inhibiting cell wall synthesis. The antibacterial activity is time dependent.
Framycetin, also known as neomycin B, is a bactericidal aminoglycoside antibiotic. Inhibition of bacterial protein synthesis and presumed interference with permeability at the cell membrane play a role in effecting bacterial cell death. Its action spectrum encompasses numerous Gram-negative and some Gram-positive bacteria.
In vitro efficacy of the combination of benzylpenicillin and framycetin has been demonstrated against: Staphylococcus spp., Streptococcus spp., Arcanobacterium spp. (Corynebacterium spp.), Escherichia coli, Klebsiella spp. and Pseudomonas spp.
Pharmacokinetic particulars
The penicillin components of the product will remain in the dry udder for up to 3 weeks. In the majority of cows the framycetin components will remain in the dry udder for 10 weeks, or until calving.