Penicillin G / Benzyl Penicillin

Spectrum: narrow spectrum antibiotic, primarily against gram positive bacteria
Cocci: Streptococci (except viridans or enterococci), pneumococci,N. gonorrhoea, N. meningitidis
Bacilli: B. anthracis, C.diptherae, Clostridia, Listeria, T. pallidum, Leptospira
Pharmacokinetics: PnG is acid labile as well as thermolabile, absorption from i.m. site is rapid, reaches most body fluids, but penetration in serous cavities & CSF is poor,
nearly 60 % plasma protein bound, plasma half life is 30 min. Tubular secretion of PnG can be blocked by probenecid, higher conc. can be achieved

Local : pain, nausea, thrombophlebitis
Systemic: mental confusion, m. twitchings, convulsion & coma at high dose, bleeding d/t interference with platelet fxs,
Hypersensitivity reactions: PnG is the most common drug implicated in drug allergy
Rash, fever, itching, urticaria, wheezing, angionerotic edema, exfoliative dermatitis, anaphylaxis (rare)
HT is more common after parenteral than oral administration
Partial cross sensitivity b/w different Pn
Procaine Pn is also allergenic
A scratch or intradermal test
If a pt is aiiergic to Pn, use alternative antibiotic
Superinfections: rare with PnG
Jarisch herxheimer reaction: seen after injection of Pn in syphilitic pt. Manifestations are fever, shivering, myalgia, & vascular collapse. This is d/t release of spirochital lytic products. It does not reoccur & does not need interruption of therapy. Aspirin & sedation may be given for symptomatic relief
Uses: Streptococcal infections
Pneumococcal infections
Meningococcal infections
Gonorrhoea
Syphilis
Diptheria
Tetanus
Gas gangrene
Rare infections like leptospirosis, anthrax, actinomycois, trench mouth, ratbite fever, listeria & pasturella
Streptococcal infections
Pneumococcal infections
Meningococcal infections
Gonorrhoea
Syphilis
Diptheria
Tetanus
Gas gangrene
Rare infections like leptospirosis, anthrax, actinomycois, trench mouth, ratbite fever, listeria & pasturella