Background Extemporaneous solutions using pure active ingredients instead of commercially available drugs are a safer option due to their lack of excipients. This could avoid potential incompatibilities and possible adverse events. It is also a better alternative, as we are preparing a solution rather than a suspension, which allow us to measure the therapeutic dose more accurately.

Purpose -To develop a flecainide syrup using pure active ingredients.

-To evaluate pH, osmolarity, organoleptic properties and microbiological stability.

Material and methods To design this extemporaneous formulation, we carried out an online bibliographic research to obtain information on the physicochemical properties of flecainide in aqueous solution. The samples were prepared according to the Formulario Nacional (PN/L/FF/004/0) and following recommendations from ‘Guia de Buenas Prácticas de Preparación de Medicamentosen los Servicios de Farmacia Hospitalaria’ (http://www.msssi.gob.es/profesionales/farmacia/pdf/GuiaBPP3.pdf).

To comply with microbiological control, we used the criteria described in chapters 2.6.1 and 5.1.9 of the European Pharmacopoeia 8th Edition. Study period: 30 days, temperature range 2–8°C (same conditions as extemporaneous formulations made from commercially available drugs: http://pharminfotech.co.nz/manual/Formulation/mixtures/index.htm).

The markers used to measure physicochemical stability were pH and osmolarity. The clarity and absence of precipitates were also assessed during the assigned period. pH and osmolarity controls were carried out by taking three samples on days 0, 7, 14, 21 and 30, using a 2001 Crison Micro pH metre and an Osmostat-OM 6020 osmometer, respectively. Microbiological controls were also performed by taking three samples on days 0, 15 and 30. These samples were processed in the microbiology laboratory.

Results The composition per 100 mL was as follows: flecainide acetate 1 g (pure active ingredient), citric acid monohydrate 0.2 g (pH regulator), simple Acofarma syrup 50 mL (which includes potassium sorbate as a preservative) and sterile water 50 mL.

The study results were: pH: 4.91 ± 0.05, 4.87 ± 0.06 and 4.91 ± 0.04.

Osmolarity: 1799.2 ± 110.5, 1851.2 ± 36.2 and 1781 ± 157.0.

Organoleptic properties: clear and transparent throughout the study period.

Microbiological control: within the target range on days 0, 15 and 30.

Conclusion All of the measured parameters were within the established range during the evaluated research period. Our extemporaneous formulation is therefore a valid alternative to the traditionally compounded flecainide syrup for paediatric usage.

No conflict of interest.