penicillin G benzathine (Bicillin L-A) (cont.)

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Penicillin G benzathine is also used for prevention of rheumatic fever or chorea.


  • Streptococcal (Group A) upper respiratory infections: Adult patients are administered a single injection of 1,200,000 units; older pediatric patients are administered a single injection of 900,000 units; infants and pediatric patients < 60 Ibs are administered 300,000 to 600,00 units.
  • Syphilis: For the treatment of primary, secondary, and latent syphilis the recommended dose is 2,400,000 units as a one-time dose. For the treatment of tertiary and neurosyphilis the recommended dose is 2,400,000 every 7 days for a total of three doses. For the treatment of congenital syphilis in patients under the age of 2, the recommended dose is 50,000 units/kg.
  • Yaws, Bejel, and Pinta: The recommended dose is 1,200,000 units administered as a single injection.
  • Prevention of rheumatic fever and glomerulonephritis: After an acute attack, penicillin G benzathine may be given in doses of 1,200,000 units once a month or 600,000 units every 2 weeks.

DRUG INTERACTIONS: Penicillin G benzathine may decrease the renal tubular secretion (elimination via the kidneys) of methotrexate (Trexall, Rheumatrex) causing an increase in blood levels of methotrexate. Patients on combination therapy should be closely monitored for the occurrence of side effects.

Penicillin G benzathine may interfere with the body's response to the live typhoid vaccine (Vivotif Berna Vaccine). The general recommendation is to wait 24 hours or longer since the administration of the last dose of the antibiotic before administrating the vaccine.

Penicillin G benzathine may decrease the effectiveness of oral contraceptives (birth control pills). Patients may need to use a backup method of contraceptive while on antibiotic treatment.

Medically Reviewed by a Doctor on 11/24/2014

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