Penicillin concentrations in serum following weekly injections of benzathine penicillin G

Chemotherapy. 1986;32(2):99-101. doi: 10.1159/000238397.


Twelve patients with syphilis were treated weekly with injections of 1.44 g (2.4 X 10(6) IU) of benzathine penicillin G for up to 3 weeks. Almost daily, serum penicillin concentrations were measured by a sensitive microbiological agar cup method. An individual and interindividual variation was found. Concentrations below the recommended 0.018 micrograms/ml were found 7 days after the first or second injection in 5 samples. Shorter intervals between injections are recommended.

MeSH terms

  • Absorption
  • Adult
  • Drug Administration Schedule
  • Female
  • Humans
  • Injections, Intramuscular
  • Male
  • Middle Aged
  • Penicillin G / blood*
  • Penicillin G Benzathine / blood*
  • Penicillin G Benzathine / therapeutic use
  • Syphilis / drug therapy


  • Penicillin G
  • Penicillin G Benzathine