title: Antibiotic stability in commercial peritoneal dialysis solutions: influence of formulation, storage and duration.
abstract: BACKGROUND
  Peritoneal dialysis (PD)-associated peritonitis is treated by administration of antibiotics mixed with the PD solution. Data on antibiotic stability for solutions in current use are limited. The aim of this study was to determine the stability of cefepime, cephazolin and ampicillin in three commercial PD solutions.
  
  
  METHODS
  Antibiotics were added to the non-glucose compartment of the Gambro (Gambrosol®) and Fresenius (Balance®) multi-compartment systems and Baxter (Dianeal®) single-compartment (glucose 2.5%) PD solutions in a sterile suite. Antibiotic stability over 3 weeks was determined using both a bioassay of bacterial inhibition and antibiotic concentrations. The influence on stability and sterility of storage conditions was determined.
  
  
  RESULTS
  The bioassay demonstrated the stability of all antibiotics for 9 days at room temperature and 3 weeks when refrigerated, except ampicillin in the Gambro solution, which displayed no bioactivity after 4 days. However, a ceiling effect in bacterial inhibition at higher antibiotic concentrations limited the ability of the bioassay to detect antibiotic degradation at relevant concentrations. Antibiotic concentrations varied with time but were comparable to the bioassay and supported stability in refrigerated solutions, except ampicillin in the Gambro solution. No bacterial contamination, marked colour change or precipitation occurred.
  
  
  CONCLUSIONS
  This study supports the stability of cephazolin and cefepime in all three PD solutions and ampicillin in only the Baxter and Fresenius PD solutions. Antibiotic stability studies should ideally be conducted prior to registration and marketing of new PD solutions.
authors.affiliation: Department of Renal Medicine, The Canberra Hospital, Woden, ACT, Australia. 1darren1@gmail.com
authors.forename: Darren M
authors.initials: DM
authors.lastname: Roberts
authors.forename: Geethanie
authors.initials: G
authors.lastname: Fernando
authors.forename: Richard F
authors.initials: RF
authors.lastname: Singer
authors.forename: Karina J
authors.initials: KJ
authors.lastname: Kennedy
authors.forename: Miriam
authors.initials: M
authors.lastname: Lawrence
authors.forename: Girish
authors.initials: G
authors.lastname: Talaulikar
mesh_terms: D000667:Ampicillin / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D002437:Cefazolin / Q000737:chemistry*; D000077723:Cefepime; D002511:Cephalosporins / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical; D015314:Dialysis Solutions / Q000737:chemistry* / Q000592:standards; D004355:Drug Stability; D004356:Drug Storage; D006801:Humans; D010530:Peritoneal Dialysis / Q000009:adverse effects*; D010538:Peritonitis / Q000188:drug therapy* / Q000209:etiology
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D015314:Dialysis Solutions; D000667:Ampicillin; D000077723:Cefepime; D002437:Cefazolin