Aim Liquid medicines are commonly prescribed for children. Multiple concentrations are in use for many drugs, increasing the risk of error. This project aimed to describe the variability in the concentrations prescribed for children in England.

Method The NHS Business Authority (NHSBA) was contacted to obtain details of all liquid medicines dispensed against FP10 prescriptions for patients aged under 18 years across a twelve month period from 1st February 2019 and 31st January 2020. For each individual active pharmaceutical ingredient (API), a list of the dispensed concentrations and total number of items dispensed at that concentration was provided in a Microsoft Excel spreadsheet. Data on medicines listed within Chapter 5 of the BNF were not provided by the NHSBA.

The data were then assessed by three paediatric pharmacists: liquid medicines not intended for oral use (e.g. nasal sprays and enemas) were excluded from analysis, as were multivitamin products, cough and cold remedies and simple antacids. Analysis included independent determination of the number of concentrations per API, total volume of API dispensed, identification of licensing status and assessment of therapeutic risk. In assessing licensing status, if there was a licensed liquid of the API at that concentration listed on the Electronic Medicines Compendium or the MHRA products website, it was assumed that all liquids supplied at that concentration were licensed.

Results Following application of exclusion criteria, 257 APIs were identified. 67 APIs were classified as high risk due to one of the following:

• multiple concentrations of unlicensed products (n=39)

• multiple concentrations of a mixture of licensed and unlicensed products (n=25)

• no unlicensed products, but multiple concentrations of licensed products and narrow therapeutic index (n=3)

For the high risk APIs, the median number of concentrations per drug was 3 (IQR 2-5), range 2-15. 18 of the high risk APIs are used primarily for neurological conditions, 17 were cardiovascular agents, and 10 were electrolyte or nutritional drugs.

The APIs with the highest number of different concentrations in use were colecalciferol (15), omeprazole (13), glycopyrronium bromide (12), ergocalciferol (10), melatonin (9), gabapentin (8), spironolactone (8), azathioprine (8), sodium chloride (8), clonidine (7) and co-careldopa (7). Nationally recommended standard concentrations have been published for azathioprine, sodium chloride and spironolactone¹; the proportion of dispensed items at the recommended standard concentration for each drug were 72%, 58% and 57% respectively.

By volume, the most frequently dispensed APIs were (number of items dispensed; number of different concentrations): colecalciferol (87,553; 15), melatonin (72,215; 9), omeprazole (58,235; 13) calcium carbonate (57,915; 5), folic acid (32,878; 3), clobazam (27,466; 7), dexamethasone (20,500; 5), glycopyrronium bromide (20,200; 12), gabapentin (14,417; 8) and diazepam (11,757; 4).

Conclusion Oral liquid medicines dispensed for children in England vary considerably in terms of concentration. For the relatively few drugs for which there is a nationally recommended standard concentration, significant variation still exists. The continued use of multiple concentrations for the same API potentially poses a significant risk to patient safety. Further national standardisation is required, and methods of driving adoption of such recommendations need to be developed.

Reference

1. Neonatal and Paediatric Pharmacists Group and Royal College of Paediatrics and Child Health, UK. Using Standardised Concentrations of Unlicensed Liquid Medicines in Children. April 2020. Available at: https://nppg.org.uk/wp-content/uploads/2020/04/NPPG-Position-Statement-18-01-V5-April-2020.pdf