|Legal status||℞-only (US)|
|ATC code||J01 QJ51|
| (what is this?)
Procaine benzylpenicillin (rINN), also known as procaine penicillin, is a form of penicillin which is a combination of benzylpenicillin and the local anaesthetic agent procaine. Following deep intramuscular injection, it is slowly absorbed into the circulation and hydrolysed to benzylpenicillin — thus it is used where prolonged low concentrations of benzylpenicillin are required.
This combination is aimed at reducing the pain and discomfort associated with a large intramuscular injection of penicillin. It is widely used in veterinary settings.
Specific indications for procaine penicillin include:
- In the United States, Bicillin C-R (a injectable suspension which 1.2 million units of benzathine penicillin and 1.2 million units of procaine penicillin per 4 ml) is not recommended for treating syphilis, since it contains only half the recommended dose of benzathine penicillin. Medication errors have been made due to the confusion between Bicillin L-A & Bicillin C-R. As a result, changes in product packaging have been made; specifically, the statement "Not for the Treatment of Syphilis" has been added in red text to both the Bicillin CR and Billin CR 900/300 syringe labels.
- Respiratory tract infections where compliance with oral treatment is unlikely
- Alongside Pen V and Erythromycin, Bicillin C-R is used to treat strep throat, given as one IM injection
- Cellulitis, erysipelas
- Procaine penicillin is also used as an adjunct in the treatment of anthrax.
Adverse effects 
At high doses procaine penicillin can cause seizures and CNS abnormalities due to procaine present in it.
Compendial status 
- Rossi S, editor, ed. (2006). Australian Medicines Handbook. Adelaide: Australian Medicines Handbook. ISBN 0-9757919-2-3.
- Centers for Disease Control and Prevention (CDC) (2005). "Inadvertent use of Bicillin C-R to treat syphilis infection--Los Angeles, California, 1999-2004". MMWR Morb. Mortal. Wkly. Rep. 54 (9): 217–9. PMID 15758893.
- United States Food & Drug Administration. "FDA Strengthens Labels of Two Specific Types of Antibiotics to Ensure Proper Use." Published December 1, 2004. Last accessed June 18, 2007.
- British Pharmacopoeia Commission Secretariat. "Index (BP 2009)". Retrieved 26 March 2010.