Prescription under medical supervision

This penicillin should be administered in a hospital setting (injections every 4 to 6 hours).

Therapeutic action

– Short-acting penicillin antibacterial


– Diphtheria, neurosyphilis
– Congenital syphilis (presence of clinical signs in the neonate and lack of adequate treatment in the mother)

Forms and strengths, route of administration

– Powder for injection in vials of:
• 1 MIU (600 mg), to be dissolved in 2 ml of water for injection or 0.9% sodium chloride
• 5 MIU (3 g), to be dissolved in 5 ml of water for injection or 0.9% sodium chloride
For IM injection or slow IV injection through an infusion tube (3 to 5 minutes) or infusion (60 minutes) in 0.9% sodium chloride or 5% glucose.


– Diphtheria
Child: 50 000 IU (30 mg)/kg every 6 hours (max. 4 MIU or 2.4 g daily)
Adult: 1 MIU (600 mg) every 6 hours

– Neurosyphilis
Adult: 2 to 4 MIU (1.2 to 2.4 g) by IV injection every 4 hours

– Congenital syphilis
• 50 000 IU (30 mg)/kg by IV injection every 12 hours from D1 to D7, then
• 50 000 IU (30 mg)/kg by IV injection every 8 hours from D8 to D10


– Diphtheria, neurosyphilis: 14 days; congenital syphilis: 10 days
– For diphtheria, change to oral route as soon as possible.

Contra-indications, adverse effects, precautions

– Do not administer to penicillin-allergic patients.
– Administer with caution to patients allergic to cephalosporins (cross-sensitivity may occur) and renal impairment (reduce dosage in patients with neurosyphilis).
– May cause:
• gastroinstestinal disturbances, pain at injection site, anaemia, allergic reactions sometimes severe;
• Jarisch-Herxheimer reaction (fever, chills, myalgia, tachycardia) in patients with syphilis;
• convulsions in the event of rapid IV injection, high dosages or renal impairment.
– Do not combine with methotrexate.
– Pregnancy: no contra-indication
– Breast-feeding: no contra-indication


– Do not confuse short-acting benzylpenicillin, administered several times a day by IV route, with long-acting penicillins (benzathine benzylpenicillin and procaine benzylpenicillin) administered by IM route only.
– Do not mix with other drugs in the same syringe or infusion.
 Storage: below 25 °C -  - 
Once reconstituted, suspension must be used immediately.