Benzylpenicillin

Benzylpenicillin, also known as penicillin G (PenG) or BENPEN, and in US military slang "Peanut Butter Shot" is an antibiotic used to treat a number of bacterial infections. This includes pneumonia, strep throat, syphilis, necrotizing enterocolitis, diphtheria, gas gangrene, leptospirosis, cellulitis, and tetanus. It is not a first-line agent for pneumococcal meningitis. Due to benzylpenicillin's limited bioavailability for oral medications, it is generally taken as an injection in the form of a sodium, potassium, benzathine, or procaine salt. Benzylpenicillin is given by injection into a vein or muscle. Two long-acting forms benzathine benzylpenicillin and procaine benzylpenicillin are available for use by injection into a muscle only. Side effects include diarrhea, seizures, and allergic reactions including anaphylaxis. When used to treat syphilis or Lyme disease a reaction known as Jarisch–Herxheimer may occur. It is not recommended in those with a history of penicillin allergy. Use during pregnancy is generally safe in the penicillin and β-lactam class of medications. Benzylpenicillin is on the World Health Organization's List of Essential Medicines. As an antibiotic, benzylpenicillin is noted to possess effectiveness mainly against gram-positive organisms. Some gram-negative organisms such as Neisseria gonorrhoeae and Leptospira weilii are also reported to be susceptible to benzylpenicillin. Adverse effects can include hypersensitivity reactions including urticaria, fever, joint pains, rashes, angioedema, anaphylaxis, serum sickness-like reaction. Rarely central nervous system toxicity including convulsions (especially with high doses or in severe renal impairment), interstitial nephritis, haemolytic anaemia, leucopenia, thrombocytopenia, and coagulation disorders. Also reported diarrhoea (including antibiotic-associated colitis). Benzylpenicillin has relatively low toxicity, except for in the nervous system, in which it is one of the most active drugs among β-lactam agents.