Benzylpenicillin, also known as penicillin G, is an antibiotic used to treat a number of bacterial infections. These include pneumonia, streptococcal infections, syphilis, necrotizing enterocolitis, diphtheria, gas gangrene, leptospirosis, cellulitis, and tetanus. Benzylpenicillin is administered by injection into a vein or muscle.
Benzylpenicillin acts by binding to specific penicillin-binding proteins (PBPs) located within the bacterial cell wall. As a result, penicillin G inhibits the third and final step of bacterial cell wall synthesis. This leads to cell lysis, which is mediated by autolytic enzymes of the bacterial cell wall (autolysins).
Rapidly absorbed after both intramuscular and subcutaneous injection. It is 45-68% bound to serum proteins, mainly albumin. Penicillin G is excreted by the kidneys after metabolism in the liver. In adults with normal renal function, the half-life is approximately 0.4-0.9 hours.
Side effects include diarrhea, seizures, and allergic reactions including anaphylaxis.
When treating syphilis or Lyme disease, a reaction known as Jarisch-Herxheimer may occur. Allergic reactions may occur with the use of penicillins.
LD50 (mouse, i.v.): 329 mg-kg-1
| ATC Code | J01CE01, S01AA14 |
| Formula | C16H18N2O4S |
| Molar Mass (g·mol−1) | 334,39 |
| Physical State | solid |
| Melting Point (°C) | 217 |
| PKS Value | 2,74 |
| CAS Number | 61-33-6 |
| PUB Number | 5904 |
| Drugbank ID | DB01053 |
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