Procaine benzylpenicillin

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.

Uses

Specific indications for procaine penicillin include:^[1]

• Syphilis
  • In the United States, Bicillin C-R (a injectable suspension which 1.2 million units of benzathine penicillin & 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.^[2] 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.^[3]
• 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

• British Pharmacopoeia ^[4]

References

See also

• Drug allergy