Disclaimer to the On-line Edition
This Manual has been designed for use in the NICU at London Health Sciences Centre (LHSC), London, Ontario, Canada, and represents clinical practice at this institution. The information contained within the Manual may not be applicable to other centres. If users of this Manual are not familiar with a drug, it is recommended that the official monograph be consulted before it is prescribed and administered. Any user of this information is advised that the contributors, Editor and LHSC are not responsible for any errors or omissions, and / or any consequences arising from the use of the information in this Manual.



  • the treatment of infections caused by susceptible bacteria (generally, Gram-positive organisms)


  • penicillin G is a natural penicillin
  • its spectrum of activity is mainly against Gram-positive organisms including Streptococcus pneumoniae and group B streptococci; penicillinase-producing strains of S. aureus and S. epidermidis are resistant to penicillin G. Some Gram-negative organisms, such as Neisseria gonorrhoeae, are usually inhibited by Penicillin G
  • penicillins are usually bactericidal in action; cell death results from interference with mucopeptide synthesis in the bacterial cell wall
  • the half life of penicillin G varies from 3.2-3.4 h in neonates less than 6 days old to 0.9-1.9 h in neonates greater than 14 days old
  • natural penicillins are widely distributed into body tissues (kidney, liver, lungs, muscle); however, penetration of natural penicillins into the CSF is poor and only increases slightly in the presence of inflamed meninges
  • the approximate degree of protein binding is 45-68%
  • approximately 30% of a dose is metabolized in the liver

Side Effects

  • convulsions can occur at high CNS levels; penicillin is rapidly removed from the CNS into the blood via an active transport process; in severe renal failure, organic acids in the CSF can accumulate and compete with penicillin for the active transport
  • may be irritating to veins; may cause thrombosis and sloughing



  • hypersensitivity reactions (eg. fever, rash, anaphylaxis) are the most common type of adverse effect. Even though allergic reactions to penicillins are very rare in the neonate, caregivers should be aware of this possibility, especially in infants whose mothers have a known penicillin hypersensitivity
  • penicillin G sodium contains 1.7 mmol Na per 106 units


  • administer by slow IV infusion over 30 minutes


    < 7 days < 2,000 g : 25,000 units/kg q12h
        : 50,000 units/kg q12h (for meningitis)
      > 2,000 g : 25,000 units/kg q8h
        : 50,000 units/kg q8h (for meningitis)
    > 7 days < 1,200 g : 25,000 units/kg q12h
        : 50,000 units/kg q12h (for meningitis)
      1,200-2,000 g : 25,000 units/kg q8h
        : 50,000 units/kg q8h (for meningitis)
      > 2,000 g : 25,000 units/kg q6h
        : 50,000 units/kg q6h (for meningitis)

Group B Streptococcal Infection with Meningitis

  • 0 - 7 days: 250,000 to 450,000 Units/kg/day IV in 3 divided doses
  • > 7 days: 450,000 Units/kg/day IV in 4 divided doses
  • Duration:

    'For infants with uncomplicated meningitis, 14 days of treatment usually is satisfactory, but longer periods of treatment may be necessary for infants with prolonged or complicated courses.'


  • 200,000 units/mL syringe prepared by Pharmacy
  • for IV use, add 4.6 mL sterile water for injection to the 1,000,000 unit vial, to prepare a concentration of approximately 200,000 units/mL



  1. Pickering LK, editor. Red Book Report of the Committee on Infectious Diseases. Elk Grove Village (IL): American Academy of Pediatrics; 2000. p.538.
  2. McEvoy G K (ed): AHFS Drug Information, American Society of Hospital Pharmacists, 1991.
  3. Nelson JD: Pocketbook of Pediatric Antimicrobial Therapy, 7th Edition, 1987, Williams and Wilkins, Baltimore.
  4. Roberts, RJ: Drug Therapy in Infants, W.B. Saunders, Toronto, 1984.
  5. Pagliaro LA and Pagliaro AM (ed): Problems in Pediatric Drug Therapy, 1987, Drug Intelligence Publ Inc, Hamilton, Illinois.
  6. Taketomo CK, Hodding JH and Kraus DM: Pediatric Dosage Handbook, Lexi-Comp Inc., Cleveland, 1992





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