Crystapen, Pencillin Sodium Biochemie

Reviewed by Dr Carl Kuschel, Dorothy Cooper
September 1998
Administration Newborn Drug Protocol Index Newborn Services Home Page

Dose and Administration

  1. 15-30 mg/kg/dose IV infusion over 15-30 minutes or IM.
  2. 60mg/kg/dose for severe sepsis and meningitis.

Add an aminoglycoside if tolerance is suspected/confirmed.

Postmenstrual Age
Postnatal Age
Dosing Interval
≤29 0 to 28 12
>28 8
30 to 36 0 to 14 12
>14 8
37 to 44 0 to 7 12
>7 8
≥45 All 6


  1. Neonatal infections caused by susceptible organisms - streptococci (non enterococcal), gonococci, congenital syphilis.

Contraindications and Precautions

  1. Caution in preterm infants, especially extreme immaturity.
  2. Caution in infants with liver, renal or gastrointestinal disease.

Clinical Pharmacology

Benzylpenicillin has bacteriostatic/bacteriocidal actions (depending on its concentration) against most gram positive bacteria and gram negative cocci. Also active against some spirochaetes and actinomycetes. Action through inhibition of biosynthesis of cell wall mucopeptide. Its action is inhibited by the enzyme penicillinase, produced during the growth of certain micro-organisms.

Well absorbed following intramuscular injection. Widely distributed at varying concentrations in body tissues and fluids. Very little passes into the CSF unless the meninges are inflamed. Moderate binding (45-65%) to human plasma protein. Rapidly excreted via the kidney, mainly unchanged. Tubular excretion is inhibited by probenecid. Reduction in serum concentrations can be achieved by haemodialysis. Half life 5-6 hours in healthy newly born preterm infants and 2 hours in full term babies > 1-2 weeks old.

Possible Adverse Effects

  1. Venous irritation, soft tissue injury at site of IV injection.
  2. Pain, soft tissue injury at site of IM injection.
  3. Gastrointestinal disturbance (nausea, vomiting, diarrhoea).
  4. Non specific rashes and skin eruptions.
  5. Fever, pruritis, urticaria.
  6. Seizures (encephalopathy with high doses greater than 400 mg/kg/day).

Special Considerations

  1. May give concurrently with aminoglycoside therapy for synergistic effect. Administer separately as intravenous administration may cause inactivation.
  2. Adjust dose in suspected renal dysfunction (usually by lengthening the dosing interval).
  3. Sodium content 1.7 mmol/gm.