Penicillin G

Penicillin G inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs) located inside the bacterial cell wall. This binding prevents the cross-linking of peptidoglycan chains, which is essential for maintaining the integrity and rigidity of the cell wall. The resulting defective cell wall leads to increased osmotic pressure, cell lysis, and ultimately bacterial death.

Adult

IV/IM for moderate to severe infections: 2 to 4 million units (MU) every 4 to 6 hours. IV for severe infections (e.g., meningitis, endocarditis): 18 to 24 MU per day, administered in divided doses every 4 to 6 hours or as a continuous infusion. IM for Syphilis (early): Benzathine Penicillin G 2.4 MU single dose.…

Pediatric

Neonates (0-7 days): 25,000 to 50,000 units/kg/dose IV/IM every 8 to 12 hours. Infants (7-28 days): 50,000 units/kg/dose IV/IM every 6 to 8 hours. Children (1 month and older): 100,000 to 250,000 units/kg/day IV/IM divided every 4 to 6 hours, depending on infection severity.

Renal adjustment

CrCl >50 mL/min: No adjustment. CrCl 10-50 mL/min: Administer usual dose every 6-8 hours. CrCl <10 mL/min: Administer usual dose every 8-12 hours. Hemodialysis: Administer dose after dialysis.

Hepatic adjustment

Generally no specific dose adjustment required.

Geriatric

Monitor renal function closely and adjust dose based on CrCl. No specific age-related dose reduction beyond renal considerations.

Max dose

Typically 24 million units/day (IV) for adults, though higher doses have been used in specific severe infections with careful monitoring.

• History of severe hypersensitivity reaction to penicillin (e.g., anaphylaxis, Stevens-Johnson syndrome)
• History of severe allergic reaction to other beta-lactam antibiotics (e.g., cephalosporins, carbapenems) due to potential cross-reactivity