penicillin G benzathine (Bicillin L-A)

What is penicillin g benzathine? What is penicillin g benzathine used for?

Penicillin G benzathine (Bicillin L-A) is a penicillin antibiotic that is given by deep intramuscular injection. Penicillin G benzathine kills susceptible bacteria by inhibiting the synthesis or formation of bacterial cell wall. It is thought to preferentially bind to specific penicillin-binding proteins (PBPs) found inside the bacterial cell wall. The end result of the inhibition of bacterial cell synthesis is cell lysis and the death of the susceptible bacteria.

Penicillin G benzathine has poor solubility and is therefore very slowly released from the site of injection. In the blood, penicillin G benzathine is broken down to penicillin G. Penicillin G benzathine formulation is released and absorbed slowly to allow for a more prolonged duration of action (drug works slowly over an longer period of time).

What brand names are available for penicillin g benzathine?

Bicillin L-A

Is penicillin g benzathine available as a generic drug?

Not available in the US

Do I need a prescription for penicillin g benzathine?


What are the side effects of penicillin g benzathine?

Side effects associated with penicillin G benzathine treatment are:


Bacterial Infections 101: Types, Symptoms, and Treatments See Slideshow

What is the dosage for penicillin g benzathine?

  • Streptococcal (Group A) upper respiratory infectionsAdult 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.

Which drugs or supplements interact with penicillin g benzathine?

: 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.

Coadminstration of penicillin G benzathine with warfarin (Coumadin) may increase the risk of bleeding. Antibiotics may inhibit vitamin K synthesis and warfarin is a vitamin K antagonist (also inhibits the action of vitamin K). Patients on combination therapy should be closely monitored for signs or symptoms of bleeding.

Is penicillin g benzathine safe to take if I'm pregnant or breastfeeding?

Penicillin G benzathine is excreted in human milk. Due to the lack of safety data, penicillin G benzathine should be used cautiously in females who are breastfeeding.

What else should I know about penicillin g benzathine?

What preparations of penicillin g benzathine are available?

Penicillin G benzathine injectable suspension: 1 ml (600,000 units per syringe), 2 ml (1,200,000 units per syringe), and 4 ml (2,400,000 units per syringe).

How should I keep penicillin g benzathine stored?

Suspension should be stored in a refrigerator, between 2 C and 8 C (36 F and 86 F).


Penicillin G benzathine injectable suspension (Bicillin L-A) is an antibiotic prescribed to treat upper respiratory infection and STDs like syphilis. Penicillin G also is prescribed to prevent rheumatic fever (chorea). Side effects, drug interactions, dosage, storage, and pregnancy safety information should be reviewed prior to using this medication.

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