Name: Penicillin G
Class: Penicillin (Penicillin G-related)
Mech.: Binds to PBPs, blocks activity of transpeptidases in terminal stages of cell wall formation. Bactericidal.
Absorption: Erratic (30%). Usu. not used orally. I.M or I.V. Prolonged effect with repository preparations (procaine, benzathine (longest)) deep IM.
Distribution: Widely distributed, little CSF unless meninges inflamed.
Metab.:
Excretion, t½: Rapidly elim. by kidneys (probenecid blocks excretion), small amt. in bile.
Toxicity/S.E.s: hypersensitivity (1-10%), painful injection, epilepsy, superinfection.
Utility: Many gram +, anaerobes, and a few gram -. Most staph. and gram - resistant. Prophylactic use (rheumatic fever, strep. infections).
Special Features: Narrow spectrum.