Uses

Indicated for the treatment of serious infections caused by susceptible gram-positive bacteria and spirochetes, including streptococcal infections, pneumococcal pneumonia, meningitis, endocarditis, syphilis, anthrax, and other infections where penicillin G remains the drug of choice. Culture and sensitivity testing should guide therapy.

Do not use if

Contraindicated in patients with a history of hypersensitivity (anaphylactic) reactions to any penicillin. Cross-reactivity with cephalosporins should be considered.

Side effects

Common adverse effects include hypersensitivity reactions (rash, urticaria, anaphylaxis), electrolyte disturbances (with potassium salt at high doses), and neurotoxicity (seizures) at very high doses. The Jarisch-Herxheimer reaction may occur in spirochetal infections.

Warnings

Serious and fatal hypersensitivity reactions, including anaphylaxis, have been reported. Obtain a careful history of allergy before use. Use with caution in patients with renal impairment due to risk of neurotoxicity and electrolyte disturbances. High-dose IV penicillin G potassium may cause hyperkalemia.

How it works

Penicillin G is a bactericidal beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis. It is active primarily against gram-positive organisms. Following intravenous infusion, peak serum concentrations are achieved immediately upon completion; it is renally eliminated with a short half-life.

Storage

Store dry powder at room temperature (20–25°C). Reconstituted solutions should be stored in a refrigerator (2–8°C) and used within the period specified by the manufacturer.