Benzathine Benzylpenicillin

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 for neurosyphilis and presence of pathological CSF findings)
yaws
pinta
For the prophylaxis of:
rheumatic fever (chorea, rheumatic carditis)
poststreptococcal glomerulonephritis
erysipelas

Dosage & Administration

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.

Sensitivity reactions including urticaria, fever, joint pain; angioedema; anaphylactic shock in hypersensitive patients.

Benzathine Benzylpenicillin has bactericidal action against many gram-positive bacteria and some gram-negative bacteria and against some spirochaetes and actinomycetes. It is considered to act through interference with the final stage of synthesis of the bacterial cell wall.The action depends upon benzyl penicillin, ability to reach and bind to certain membrane bound protein known as penicillin-binding proteins that are located beneath the cell wall. Its action is inhibited by penicillinase and other beta-lactamase enzymes. When benzathine penicillin is given by intramuscular injection it forms a depot from which it is slowly released & hydrolyzed to benzyl penicillin. Peak plasma concentrations are produced in about 24 hours and eective concentrations of benzyl penicillin are maintained for up to 4 weeks. Due to the slow absorption from the site of injection, benzyl penicillin has been detected in the urine for up to 12 weeks after a single dose.