Benzathine benzylpenicillin

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Benzathine benzylpenicillin
Combination of
Clinical data
Trade namesBicillin L-A,[1] Permapen, others
Other namespenicillin benzathine benzyl, benzathine penicillin, penicillin G benzathine, benzylpenicillin benzathine[2]
AHFS/Drugs.comProfessional Drug Facts
License data
  • AU: A
Routes of
Intramuscular injection[3]
ATC code
Legal status
Legal status
CAS Number
PubChem CID
E numberE708 (antibiotics) Edit this at Wikidata
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ECHA InfoCard100.014.782 Edit this at Wikidata
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Benzathine benzylpenicillin, also known as benzathine penicillin G (BPG), is an antibiotic medication useful for the treatment of a number of bacterial infections.[3] Specifically it is used to treat strep throat, diphtheria, syphilis, and yaws.[3][4] It is also used to prevent rheumatic fever.[4] It is given by injection into a muscle.[3][4] It is known as "Peanut Butter Shot" in US military slang due to its appearance.[5]

Side effects include allergic reactions including anaphylaxis, and pain at the site of injection.[4] When used to treat syphilis a reaction known as Jarisch-Herxheimer may occur.[4] It is not recommended in those with a history of penicillin allergy or those with syphilis involving the nervous system.[4][3] Use during pregnancy is generally safe.[3] It is in the penicillin and beta lactam class of medications and works via benzylpenicillin.[3][4] 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]

Medical uses[edit]

It is used to treat strep throat, diphtheria, syphilis, and yaws.[3][4]


A single large 1.2-million-unit dose of intramuscular BPG is given to US military recruits. The Army in particular has a policy to inject all recruits if not allergic, though supply issues and individual base choices have reduced the coverage. A retrospective analysis shows that it reduces the rate of all-cause acute respiratory disease by 32% among Army recruits.[9]

Adverse effects[edit]

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

The possible adverse effects are generally similar to other forms of penicillin. BPG is overall well-tolerated, but pain from the injection site is a common concern.[10]

Mechanism of action[edit]

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.[citation needed]

Society and culture[edit]

It is marketed by Pfizer (formerly by Wyeth) under the trade name Bicillin L-A.[11]

Compendial status[edit]


  1. ^ Hamilton R (2015). Tarascon Pocket Pharmacopoeia 2015 Deluxe Lab-Coat Edition. Jones & Bartlett Learning. p. 94. ISBN 9781284057560.
  2. ^ a b Engel J, Kleemann A, Kutscher B, Reichert D, eds. (2009). Pharmaceutical Substances: Syntheses, Patents and Applications of the most relevant APIs (5th ed.). Georg Thieme Verlag. p. 134. ISBN 9783131792754. Archived from the original on 20 December 2016.
  3. ^ a b c d e f g h "Penicillin G Benzathine (Professional Patient Advice) -". Archived from the original on 20 December 2016. Retrieved 10 December 2016.
  4. ^ a b c d e f g h 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.
  5. ^ Kirkpatrick T (11 February 2020). "Why the Most Dreaded Injection is Called the 'Peanut Butter' Shot". Retrieved 21 December 2021.
  6. ^ Ebadi M (2007). "Penicillin G". Desk Reference of Clinical Pharmacology (2nd ed.). CRC Press. p. 555. ISBN 9781420047448. Archived from the original on 20 December 2016.
  7. ^ US patent 2627491, Szabo JL, Bruce WF, "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. ^ Ball JD, Prosperi MA, Brown A, Chen X, Kenah E, Yang Y, et al. (October 2018). "The role of benzathine penicillin G in predicting and preventing all-cause acute respiratory disease in military recruits: 1991-2017". Epidemiology and Infection. 146 (14): 1854–1860. doi:10.1017/S0950268818001838. PMC 9506690. PMID 29974837.
  10. ^ Gartlan WA, Rahman S, Reti K (2023). "Benzathine Penicillin". StatPearls. StatPearls Publishing. PMID 29939545.
  11. ^ "Bicillin® L-A" (PDF). US FDA. Retrieved 31 July 2023.
  12. ^ British Pharmacopoeia Commission Secretariat. "Index (BP 2009)" (PDF). Archived from the original (PDF) on 11 April 2009. Retrieved 26 March 2010.

External links[edit]