Kombinlangan antibiotik, ampitsillin va oksatsillin ta'sir doirasini birlashtiradi. Ampitsillin yarim sintetik penitsillin bo'lib, bakteritsid ta'sir ko'rsatadi, kislota chidamli. Gram-musbat, penitsillinaz ishlab chiqarmaydigan (Staphylococcus spp., Streptococcus spp., Streptococcus pneumoniae) va gram-manfiy (Neisseria gonorrhoeae, Neisseria meningitidis, Escherichia coli, Salmonella spp., Shigella spp., Proteus mirabilis, Haemophilus influenzae) mikroorganizmlarga faol. Oksatsillin penitsillinazga chidamli yarim sintetik antibiotik bo'lib, penitsillinlar guruhiga kiradi, kislota chidamli; gram-musbat mikroorganizmlarga (Staphylococcus spp., Streptococcus spp., shu jumladan Streptococcus pneumoniae, Actinomyces spp., Bacillus anthracis, Corynebacterium diphtheriae, anaerob sporali tayoqchalar, shu jumladan Clostridium), gram-manfiy kokklarga (Neisseria gonorrhoeae, Neisseria meningitidis), Escherichia coli, Proteus mirabilis, Haemophilus influenzae, Klebsiella pneumoniae, Actinomyces spp., Treponema spp. ga qarshi bakteritsid ta'sir ko'rsatadi. Kombinatsiyaga Pseudomonas aeruginosa va boshqa fermentlamaydigan gram-manfiy bakteriyalar, ko'pchilik Proteus vulgaris shtammlari, Providencia rettgeri, Morganella morganii chidamli.