BENZATHINE BENZYLPENICILLIN

Broad spectrum penicillin antibacterial with prolonged action (15 to 20 days)

Dosage Forms

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Powder for injection

2.4 MU (= 1.44 g benzyl penicillin)

Uses

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  • Severe streptococcal sore throat and tonsillitis
  • Syphilis (except neurosyphilis)
  • Prophylaxis of congenital syphilis in newborn when mother tests positive

Dose and Duration

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Given as deep intramuscular (IM) injection

Streptococcal sore throat and tonsillitis
Adult: 1.2 MU as single dose
Child <30 kg: 30,000 IU/kg as single dose
Early syphilis (infection of less than 2 years)
Adult: Early syphilis (infection of less than 2 years)
Late syphilis (asymptomatic infection lasting more than 2 years)
Adult: 2.4 MU IM (half dose into each buttock) once per week for 3 weeks
Prophylaxis of congenital syphilis in newborn
Neonate: 50,000 IU/kg IM single dose; follow up every 2 weeks

Preparation

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  • Dissolve powder in 8 ml of water for injection; shake suspension before administration

Contraindications

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  • Penicillin allergy
  • High plasma calcium levels
  • Cephalosporin allergy (cross-sensitivity may occur)
  • Neurosyphilis

Side Effects

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  • Stomach upset
  • Allergic reaction
  • Jarisch-herxheimer reaction in syphilis (rash, fever, feel ing of sickness)

Interactions

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  • Methotrexate (increased risk of methotrexate toxicity)

Patient instructions

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  • Report to the health facility immediately if skin rash develops after receiving the injection

Pregnancy

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  • Can be used

Breastfeeding

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  • Can be used

Storage

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  • Once reconstituted, suspension must be kept refrigerated at 2–8°C and used within 24 hours

⚠️ Caution

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  • Never give IV injection or infusion as heart problems may occur. Use IM route only
  • Do not mix with other injections in the same syringe
  • Prevent Jarisch-herxheimer reaction in syphilis with 3 doses of 20 mg oral prednisolone every 12 hours
  • Benzathine penicillin should not be confused with benzyl penicillin which has a short duration of action (6 hours)