Amoxicillin EntryintoHumanCerebrospinal Fluid: Comparison withAmpicillin

Amoxicillin isasemisynthetic penicillin which ischemically related toampicillin andhasa similar spectrum ofantibacterial activity. Because ofbetter intestinal absorption, theserum levels obtained afteroraladministration of amoxicillin aretwice ashighasthose obtained withsimilar doses ofampicillin (4). Since ampicillin isanimportant drugforthe treatment ofpyogenic meningitis, itisimportant tohaveinformation about theconcentrations of ampicillin incerebrospinal fluid (CSF). A study onthepenetration ofamoxicillin andpenicillin Ginto theCSFofdogssuggested thatamoxicillinpossessed agreater ability thanpenicillin G topenetrate intotheCSFafter aslowintravenousinfusion (1). Theconcentration ofantibiotic inthenormalCSFmaybeimportant for thecontinued treatment ofpatients during the convalescent period ofmeningitis, since atthis timethemeninges aremuchless inflamed. However, there arenodataavailable about thepenetration ofamoxicillin intohumanCSF.This papertherefore reports theresults ofastudy undertaken tocompare theentry ofamoxicillin andampicillin intoCSFofhumanadults withoutmeningeal inflammation.