Benzathine Benzylpenicillin

Indications

Benzathine Benzylpenicillin, given as benzylpenicillin injection, is used in adults, adolescents, children and neonates, both to treat and to prevent certain infections. For treatment, it is used in erysipelas, syphilis, yaws and pinta. In syphilis, this means early syphilis (primary and secondary) and latent syphilis. Latent syphilis is covered except when there is neurosyphilis or pathological CSF findings. For prevention, it is used in rheumatic fever (chorea and rheumatic carditis), poststreptococcal glomerulonephritis and erysipelas.

⚠️ Always consult a registered physician before taking any medicine.

Pharmacology

Benzathine Benzylpenicillin kills many gram-positive bacteria and some gram-negative bacteria, and it also works against some spirochaetes and actinomycetes. It is thought to act by interfering with the final stage of building the bacterial cell wall. This depends on the ability of benzyl penicillin to reach and bind certain membrane-bound proteins, known as penicillin-binding proteins, which sit beneath the cell wall. Penicillinase and other beta-lactamase enzymes inhibit its action.

When benzathine penicillin is given by intramuscular injection, it forms a depot at the site. From there it is released slowly and hydrolyzed to benzyl penicillin. Peak plasma concentrations come in about 24 hours, and effective concentrations of benzyl penicillin last for up to 4 weeks. Because absorption from the injection site is so slow, benzyl penicillin has been found in the urine for up to 12 weeks after a single dose.

Pregnancy & Breastfeeding

Benzathine Penicillin is in pregnancy category B. Even so, it should not be given during pregnancy unless the doctor judges that it is clinically justified. Take special care in the first three months of pregnancy. Penicillin passes into breast milk, so it is probably best for a mother to stop breast-feeding while she is being given penicillin, so the infant isn't exposed to the drug unnecessarily.

⚠️ Talk to your doctor before taking any medicine during pregnancy or while breastfeeding.

Dosage Reference

⚠️ Reference ranges from official sources only. Consult your doctor for personalized dosing.

Adults: For early syphilis, Benzathine Benzylpenicillin is given as a single dose of 2.4 million units by deep intramuscular injection. In late syphilis, the same dose is given once a week for a total of 3 doses. Neonates may be given a single intramuscular injection of 50,000 units per kg body weight to treat congenital syphilis, provided there is no evidence of infection in the CSF. For streptococcal infection, the usual dose is a single intramuscular dose of 1.2 million units. Children may be given an intramuscular dose of 0.3 million to 0.9 million units, depending on body weight. To prevent recurrence of acute rheumatic fever, 1.2 million units may be given intramuscularly every 4 weeks. For children, doses of 0.6 or 1.2 million units have been recommended. For administration, 3 to 4 ml of water for injection is added to the vial of 12 Lac injection, or as directed by the physician.