A new study advocates for standard nomenclature for drugs named with the co-drug format, including high-volume drugs such as co-codamol, co-amoxiclav and co-trimoxazole, to reduce medication errors.
The researchers recommend a standardised naming system stating each component’s international nonproprietary name (INN) followed by dose information in the x + y format both on the box and in prescribing resources.
The World Health Organization (WHO) set up the International Nonproprietary Naming Committee in the 1970s, but increasingly popular multidrug products do not fall under the remit of this nomenclature.
Here, the researchers identified 26 combination formulations historically named with the co-drug format in the United Kingdom and undertook a literature search to identify prescribing errors linked to co-drug products. Most of these drugs have been prescribed in the UK in the last year, with 11 prescribed more than 2,000 times and accounting for approximately 99% of general practice prescriptions for co-drugs in England and Wales.
On 14 March 2024, the researchers searched Google Scholar, Scopus and PubMed for scientific studies reporting medication errors that involved co-drugs.
The findings showed the most common medication errors occurred with co-amoxiclav, which caused 16% of errors (n = 41/262). This was primarily due to inappropriate medication selection. Co-amoxiclav was also found to be one of the most common drugs involved in intravenous administration errors and it also ranked highly in dispensing and prescribing incidences at a Welsh hospital and a London hospital, respectively.
In decreasing order of frequency, medication errors occurred with co-amilofruse – where the name caused patient and clinician confusion – and also co-beneldopa, co-careldopa, co-codamol, co-dydramol and co-trimoxazole. For these five co-drugs, pharmacy errors such as the substitution of controlled release for immediate release, look-alike errors relating to similar drug names, and dosing errors due to confusion about how the manufacturers detailed the dosage were involved.
The researchers noted that co-drug names most likely contributed to these errors, but the impact is difficult to quantify across disparate studies.
The research showed that pharmacists played a critical role in correcting co-drug name errors before they could impact patients. However, the researchers maintain that there is a need for a standardised system of nomenclature to prevent confusion and reduce the risk of patient harm.
They hope that their proposed naming system would enhance clarity and safety during prescribing and administration, particularly for high-volume drugs such as paracetamol + codeine (co-codamol), amoxicillin + clavulanic acid (co-amoxiclav) and trimethoprim + sulfamethoxazole (co-trimoxazole).
Reference
Kavanagh, O et al. Errors associated with co-names of medicines: The nomenclature of combination medicinal products. Br J Clin Pharmacol. 2024; Sept 10: DOI:10.1111/bcp.16222.
