The National Patient Safety Team identified an issue related to confusion associated with different benzylpenicillin medicines.

There are three injectable salts of benzylpenicillin available in England, and they are not interchangeable: 

• Benzylpenicillin sodium
• Benzathine benzylpenicillin
• Procaine benzylpenicillin

 An incident report described the incorrect salt of injectable penicillin being supplied via pharmacy wholesale supply for inclusion in the emergency bags of an ambulance service. The incorrect formulation was administered to a patient with symptoms of potential meningitis. 

A review of national reporting systems for a 3-year period identified similar reports describing potential confusion between the different salt formulations of benzylpenicillin. We shared findings of our analysis of these reports with: 

• the BNF editorial board who added important safety information to relevant monographs
• the dictionary of medicines and devices (dm+d) content committee who amended the entry for benzylpenicillin sodium to align it with that used in other key resources
• the MHRA with a request that they consider reviewing the nomenclature used in relevant product labelling and packaging
• the national Medication Safety Officer network
• the Specialist Pharmacy Service who published their resource “Managing the risk of confusion between injectable penicillin salts”.

These interventions support safer selection, prescribing and administration of different penicillin salt containing medicines.