When a medication prescribed for a patient is unavailable commercially at the dose required, pharmacists prepare the medication especially for the patient using commercially available preparations (for example by grinding tablets and diluting this in a suitable liquid to achieve an oral preparation of lower drug concentration). This is called ‘extemporaneous’ preparation and is often compounded for paediatric or elderly patients. However unlike commercially available products, the stability of the extemporaneous medication is unknown and little guidance on an appropriate shelf-life and storage conditions can be given. Such preparations may be subject to physical, chemical or microbiological degradation. It is vital to ensure that these preparations are stable and hence effective and safe over their period of use.
Losartan is a drug used in children and must be prepared extemporaneously at a lower concentration than is available commercially. It is used to treat hypertension in children at Our Lady’s Hospital for Sick Children and is compounded in the Pharmacy for oral use from Losartan tablets. It is currently assigned an arbitrary expiry date and storage conditions. This project aims to study the stability of these preparations stored at room temperature and in the fridge. Preparations will be removed over 4 weeks and analysed for their chemical and physical stability. The effectiveness of preservatives in reducing the potential for bacterial contamination of the preparations will also be analysed. The results of these studies will allow us to recommend appropriate storage condition and expiry time for the Losartan preparations.
