title: Penicillin concentrations in sera and tonsils after intramuscular administration of benzathine penicillin G to children.
abstract: BACKGROUND
  The optimal regimen of benzathine penicillin G for secondary prevention of rheumatic fever is controversial. Data from serum pharmacokinetic studies do not fully agree on the period of protection after drug administration. Data from concentration of penicillin in tonsils may provide additional information.
  
  
  METHODS
  To evaluate penicillin concentrations in palatine tonsils and in sera 1, 10, 14 and 21 days after intramuscular injection of benzathine penicillin G 40,000 IU/kg, 58 children between 4 and 12 years of age with chronic tonsillitis and indication for tonsillectomy were given the study drug 1, 10, 14 or 21 days before surgery. Blood and tonsil samples were obtained during surgery, and penicillin concentrations were determined microbiologically by the agar well diffusion technique.
  
  
  RESULTS
  Mean serum penicillin concentrations 1, 10, 14 and 21 days after drug administration were, respectively, 0.080, 0.031, 0.023 and 0.014 microg/ml. Mean penicillin concentrations in tonsils at 1, 10, 14 and 21 days were 0.023, 0.010, 0.007 and 0.002 microg/g, respectively. Detectable penicillin concentration in tonsils (method sensitivity, 0.006 microg/g) was obtained in all patients on Day 1 and in 91% and 83.3% of patients on Days 10 and 14, respectively. By Day 21 this proportion was reduced to 30%.
  
  
  CONCLUSIONS
  The results of this study suggest that penicillin values may be inadequate for prevention of rheumatic fever by Week 3 of administration in a majority of children.
authors.affiliation: Department of Otolaryngology, Clinical Hospital of the University of São Paulo School of Medicine, Brazil. upeloso@uol.com.br
authors.forename: Ulisses Carlos
authors.initials: UC
authors.lastname: Peloso
authors.forename: José Celso Rodrigues
authors.initials: JC
authors.lastname: De Souza
authors.forename: Marco Aurelio
authors.initials: MA
authors.lastname: Botino
authors.forename: Aroldo
authors.initials: A
authors.lastname: Miniti
mesh_terms: D000704:Analysis of Variance; D001682:Biological Availability; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D010401:Penicillin G Benzathine / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D011336:Probability; D011446:Prospective Studies; D012213:Rheumatic Fever / Q000517:prevention & control*; D012680:Sensitivity and Specificity; D014069:Tonsillitis / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D010401:Penicillin G Benzathine