Benzathine benzylpenicillin

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Benzathine benzylpenicillin
Benzylpenicillin-Benzathin Structural Formula V.1.svg
Combination of
Trade namesBicillin L-A,[1] Permapen, others
Other namespenicillin benzathine benzyl, benzathine penicillin, penicillin G benzathine, benethamine penicilline, benzylpenicillin benzathine[2]
Clinical data
Defined daily dose3.6 grams[4]
External links
AHFS/Drugs.comProfessional Drug Facts
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Benzathine benzylpenicillin, also known as benzathine penicillin G, is an antibiotic useful for the treatment of a number of bacterial infections.[3] Specifically it is used to treat strep throat, diphtheria, syphilis, and yaws.[5][3] It is also used to prevent rheumatic fever.[5] It is given by injection into a muscle.[5]

Side effects include allergic reactions including anaphylaxis, and pain at the site of injection.[5] When used to treat syphilis a reaction known as Jarisch-Herxheimer may occur.[5] It is not recommended in those with a history of penicillin allergy or those with syphilis involving the nervous system.[5][3] Use during pregnancy is generally safe.[3] It is in the penicillin and beta lactam class of medications and works via benzylpenicillin.[3][5] The benzathine component slowly releases the penicillin making the combination long acting.[6]

Benzathine benzylpenicillin was patented in 1950.[2][7] It is on the World Health Organization's List of Essential Medicines.[8] The wholesale cost in the developing world is about 0.27 to US$1.71 for a course of treatment.[9] In the United States the medication costs 50 to US$100 for a dose as of 2015.[1] In the United Kingdom it costs the NHS about 0.95 to 1.89 pounds a dose as of 2015.[10]

Medical uses

2,400,000 units of Bicillin L-A brand of benzylpenicillin, for deep intramuscular injection


The defined daily dose is 3.6 grams by mouth.[4] 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.[11] 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.[11] 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.[11] It may also be used to prevent rheumatic fever with monthly injections.[11]

Side effects

Pregnancy and breastfeeding

Use is generally okay in pregnancy and breastfeeding.[11]

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.

Compendial status


  1. 1.0 1.1 Hamilton, Richart (2015). Tarascon Pocket Pharmacopoeia 2015 Deluxe Lab-Coat Edition. Jones & Bartlett Learning. p. 94. ISBN 9781284057560.
  2. 2.0 2.1 Engel, Jürgen; Kleemann, Axel; Kutscher, Bernhard; Reichert, Dietmar (2014). Pharmaceutical Substances, 5th Edition, 2009: Syntheses, Patents and Applications of the most relevant APIs (5 ed.). Georg Thieme Verlag. p. 134. ISBN 9783131792754. Archived from the original on 20 December 2016.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 "Penicillin G Benzathine (Professional Patient Advice) -". Archived from the original on 20 December 2016. Retrieved 10 December 2016.
  4. 4.0 4.1 "WHOCC - ATC/DDD Index". Retrieved 1 September 2020.
  5. 5.0 5.1 5.2 5.3 5.4 5.5 5.6 World Health Organization (2009). Stuart MC, Kouimtzi M, Hill SR (eds.). WHO Model Formulary 2008. World Health Organization. pp. 98, 104. hdl:10665/44053. ISBN 9789241547659.
  6. Ebadi, Manuchair (2007). Desk Reference of Clinical Pharmacology, Second Edition (2 ed.). CRC Press. p. 555. ISBN 9781420047448. Archived from the original on 20 December 2016.
  7. US patent 2627491, Joseph Lester Szabo & William F Bruce, "Penicillin salts of substituted alkylene diamines", published 1953-02-03, issued 1953-02-03, assigned to Wyeth LLC and Wyeth Inc 
  8. World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
  9. "Penicillin, Benzathine Benzyl". International Drug Price Indicator Guide. Retrieved 8 December 2016.
  10. British national formulary : BNF 69 (69 ed.). British Medical Association. 2015. p. 367. ISBN 9780857111562.
  11. 11.0 11.1 11.2 11.3 11.4 "BENZATHINE BENZYLPENICILLIN injectable - Essential drugs". Retrieved 1 September 2020.
  12. British Pharmacopoeia Commission Secretariat. "Index (BP 2009)" (PDF). Archived from the original (PDF) on 11 April 2009. Retrieved 26 March 2010.

External links