Benzylpenicillin injection is indicated in adults, adolescents, children, and neonates for the treatment and prophylaxis of the following infections:

For the treatment of:

• Erysipelas
• Syphilis: early syphilis (primary and secondary)
• Latent syphilis (except neurosyphilis and cases with pathological CSF findings)
• Yaws
• Pinta

For the prophylaxis of:

• Rheumatic fever (including chorea and rheumatic carditis)
• Post-streptococcal glomerulonephritis
• Erysipelas

Benzathine Benzylpenicillin has bactericidal activity against many gram-positive bacteria, some gram-negative bacteria, and certain spirochaetes and actinomycetes. It acts by interfering with the final stage of bacterial cell wall synthesis. Its action depends on the ability of benzylpenicillin to reach and bind to specific membrane-bound proteins known as penicillin-binding proteins, which are located beneath the bacterial cell wall. Its activity is inhibited by penicillinase and other beta-lactamase enzymes. When administered by intramuscular injection, benzathine penicillin forms a depot at the injection site, from which it is slowly released and hydrolyzed to benzylpenicillin. Peak plasma concentrations are reached in about 24 hours, and effective concentrations of benzylpenicillin may be maintained for up to 4 weeks. Due to slow absorption from the injection site, benzylpenicillin may be detected in the urine for up to 12 weeks after a single dose.

For early syphilis: a single dose of 2.4 million units by deep intramuscular injection is given.

In late syphilis: the above dose is given at weekly intervals for a total of 3 doses. Neonates may be given a single intramuscular injection of 50,000 units per kg body weight for the treatment of congenital syphilis provided there is no evidence of infection in the CSF.

For streptococcal infection: it is usually given as a single intramuscular dose of 1.2 million units.

Children may be given intramuscular dose of 0.3 million to 0.9 million units according to body weight. To prevent recurrence of acute rheumatic fever 1.2 million units may be given intramuscularly every 4 weeks; doses of 0.6 or 1.2 million units have been recommended for children.

For administration 3-4 ml water for injection is added to the vial of 12 Lac injection or as directed by the physician.

No potentially hazardous drug interactions have been described.

Benzathine Benzylpenicillin should not be given to patients with known hypersensitivity to penicillin.

Hypersensitivity reactions may occur, including urticaria, fever, joint pain, angioedema, and anaphylactic shock in sensitive patients.

Pregnancy Category B. Benzathine Benzylpenicillin should not be used during pregnancy unless, in the physician’s judgment, its use is clinically justified. Special caution should be taken during the first three months of pregnancy. As penicillin is excreted in breast milk, it is generally advisable for mothers to stop breastfeeding while receiving penicillin in order to avoid unnecessary exposure of the infant to the drug.

Benzathine Benzylpenicillin should be used with caution in patients with a history of allergy and in those with renal impairment.

Long-acting penicillin

Store below 30°C, protected from light and moisture. This medicine should be dispensed only on the prescription of a registered physician.