Оксациллин натриевая соль

Crystalline

Oxacillin sodium salt is a narrow spectrum beta-lactam antibiotic. It can be used in analytical study of combination of reversed phase liquid chromatography and zwitterion exchange-reversed phase-hydrophilic interaction mixed-mode liquid chromatography coupled with mass spectrometry for anal. of antibiotics and their impurities.

Oxacillin sodium, (5-methyl3-phenyl-4-isoxazolyl)penicillinsodium monohydrate (Prostaphlin), is the salt of a semisyntheticpenicillin that is highly resistant to inactivation bypenicillinase. Apparently, the steric effects of the 3-phenyland 5-methyl groups of the isoxazolyl ring prevent the bindingof this penicillin to the β-lactamase active site and,thereby, protect the lactam ring from degradation in muchthe same way as has been suggested for methicillin. It is alsorelatively resistant to acid hydrolysis and, therefore, may beadministered orally with good effect.
Oxacillin sodium, which is available in capsule form, isreasonably well absorbed from the gastrointestinal (GI)tract, particularly in fasting patients. Effective plasma levelsof oxacillin are obtained in about 1 hour, but despite extensiveplasma protein binding, it is excreted rapidly throughthe kidneys. Oxacillin experiences some first-pass metabolismin the liver to the 5-hydroxymethyl derivative. Thismetabolite has antibacterial activity comparable to that ofoxacillin but is less avidly protein bound and more rapidlyexcreted. The halogenated analogs cloxacillin, dicloxacillin,and floxacillin experience less 5-methyl hydroxylation.
The use of oxacillin and other isoxazolylpenicillinsshould be restricted to the treatment of infections causedby staphylococci resistant to penicillin G. Although theirspectrum of activity is similar to that of penicillin G, theisoxazolylpenicillins are, in general, inferior to it and thephenoxymethylpenicillins for the treatment of infectionscaused by penicillin G-sensitive bacteria. Because isoxazolylpenicillinscause allergic reactions similar to thoseproduced by other penicillins, they should be used withgreat caution in patients who are penicillin sensitive.

This antibiotic, which is stable to penicillinase, is purified by recrystallisation from isoPrOH and dried in vacuo. Its solubility in H2O at 25o is 5%. [Doyle et al. Nature 192 1183 1961, Review: Chain et al. Antibiotics (Oxford University Press) 2 1949.]