|Trade names||Bicillin L-A, Permapen, others|
|Other names||penicillin benzathine benzyl, benzathine penicillin, penicillin G benzathine, benethamine penicilline, benzylpenicillin benzathine|
|Defined daily dose||3.6 grams|
|AHFS/Drugs.com||Professional Drug Facts|
|(what is this?)|
Benzathine benzylpenicillin, also known as benzathine penicillin G, is an antibiotic useful for the treatment of a number of bacterial infections. Specifically it is used to treat strep throat, diphtheria, syphilis, and yaws. It is also used to prevent rheumatic fever. It is given by injection into a muscle.
Side effects include allergic reactions including anaphylaxis, and pain at the site of injection. When used to treat syphilis a reaction known as Jarisch-Herxheimer may occur. It is not recommended in those with a history of penicillin allergy or those with syphilis involving the nervous system. Use during pregnancy is generally safe. It is in the penicillin and beta lactam class of medications and works via benzylpenicillin. The benzathine component slowly releases the penicillin making the combination long acting.
Benzathine benzylpenicillin was patented in 1950. It is on the World Health Organization's List of Essential Medicines. The wholesale cost in the developing world is about 0.27 to US$1.71 for a course of treatment. In the United States the medication costs 50 to US$100 for a dose as of 2015. In the United Kingdom it costs the NHS about 0.95 to 1.89 pounds a dose as of 2015.
The defined daily dose is 3.6 grams by mouth. For strep throat it is given at a dose of 900 mg (1.2 MIU) in those over 30 kg and half that dose for those under 30 kg. For syphilis the dose is 1.8 grams (2.4 MIU) per injection in adults and 37.5 mg/kg (50,000 IU/kg) per injection. For strep throat and early syphilis it is given as a single dose while for late syphilis it is given a three injection over three weeks. It may also be used to prevent rheumatic fever with monthly injections.
Pregnancy and breastfeeding
Use is generally okay in pregnancy and breastfeeding.
Mechanism of action
It is in the penicillin class of medications. It is slowly absorbed into the circulation, after intramuscular injection, and hydrolysed to benzylpenicillin in vivo. It is the drug-of-choice when prolonged low concentrations of benzylpenicillin are required and appropriate, allowing prolonged antibiotic action over 2–4 weeks after a single IM dose.
Society and culture
It is marketed by Pfizer (formerly by Wyeth) under the trade name Bicillin L-A.
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