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Twice-a-Day Treatment Is Effective for Streptococcal Pharyngitis


  • How effective is BID dosing penicillin in treating streptococcal pharyngitis compared to TID dosing of penicillin?

Clinical Bottom Lines

  1. BID penicillin is just as effective as TID/QID dosing of penicillin in treating streptococcal pharyngitis.
  2. QD penicillin was found to have a lower cure rate, compared to more frequent dosing.
  3. There is no data to show that this regimen prevents rheumatic fever.

Summary of Key Evidence

  1. A meta-analysis compared 6 studies that looked at the dosing interval of penicillin for streptococcal pharyngitis, specifically QD/BID vs TID/QID.1
  2. Each study was assigned a quality score based on 3 categories: 1) diagnostic accuracy (if the study was done Dec-May, excluded anyone less than 3 years, and if diagnosis was made by symptoms of streptococcal pharyngitis, not viral pharyngitis); 2) distinguish re-infection after cure from persistent infection (follow-up cultures within 14 days of completing treatment; comparing pre-treatment and post-treatment GABHS serotypes); 3) general elements of study design (investigators blind to treatment, compliance of treatment assessed, subject withdrawals and reasons for withdrawal discussed, assessed adequacy of randomization by demographic variables).
  3. The meta-analysis measured the difference in the proportion of each treament group cured, with a 95% confidence interval.
  4. There was no difference in the cure rate between BID and TID/QID dosing of penicillin.
  5. QD dosing of penicillin had a decreased efficacy in treating streptococcal pharyngitis.
  6. The study also analyzed a few subgroups: no difference in cure rate was found within the pediatric population; no difference was found based on the total daily dose of penicillin.
  7. Of the 6 studies analyzed, only one study had a treatment arm for amoxicillin.

Additional Comments

  • The meta-analysis was valid: the studies included were all randomized controlled trials, the results were consistent from study to study.
  • The difference between study designs made the analysis more difficult.
  • The analysis did not assess the power of the study.
  • More studies need to be done to assess dosing frequency of amoxicillin against streptococcal pharyngitis.


  1. Lan AJ, Colford JM. The impact of dosing frequency on the efficacy of 10-day penicillin or amoxicillin therapy for streptococcal tonsillopharyngitis: a meta-analysis. Pediatrics 2000; 105: e19.

CAT Author: Lynn Johnson, MD

CAT Appraisers: Alex Kemper, MD

Date appraised: July 30, 2001

Last updated November 28, 2006
Department of Pediatrics and Communicable Diseases
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