Aims To retrospectively analyse any trends in magnesium levels for patients on omeprazole 10 mg/5 ml suspension in response to Medicines and Healthcare products Regulatory Agency (MHRA) Drug Safety Update April 2012.¹ Omeprazole 10 mg/5 ml was chosen as it is the most common proton pump inhibitor (PPI) and formulation used at the Trust. Data will be used to indicate to paediatric clinicians if further study is needed and the extent (if any) of hypomagnesaemia in these patients. The data will also be used to review future changes in prescribing habits when PPI's especially for patients who are on them long term.

Method Patients who had been dispensed omeprazole 10 mg/5 ml from January to June 2012 were identified using the electronic pharmacy patient medical records system (Ascribe) and any magnesium levels available for these patients using the electronic paediatric laboratory medicine system (ICE). Data was also collected for the use, if any, of magnesium supplements in that time for these patients. A magnesium reference range of 0.6–1.0 mmol/l was used in this analysis. The data was analysed using Microsoft Excel 2007.

Results From the data analysed so far from a possible 234 patients, the average dose of omeprazole prescribed was 20 mg once a day. The average age of these patients was 12.75 years and 25% of these patients started on a different oral formulation before being transferred on to the 10 mg/5 ml suspension. 50% of patients did not have a magnesium level measured. Just over 17% had a low magnesium level (range=0.49–058 mmol/l) and none were on magnesium supplements. About 8% patients had high magnesium level and subsequently they were on a magnesium supplement in that 6 month period.

Conclusions The MHRA report published in April 2012 highlights the need to assess for hypomagnesaemia in patients using a PPI especially following long term use. This study highlights that a trend in a paediatric population for hypomagnesaemia may also be seen but only 50% of patients assessed have had their magnesium levels measures which suggests that prescribers do not monitor magnesium levels for these patients.

Further study will be needed and the data should be presented to paediatric prescribers highlighting the extent of hypomagnesaemia in this group of patients. We should bear in mind the clinical risk that this may lead to such as other electrolyte imbalances² and Torsade de pointes² if not monitored.