Background and Importance Status epilepticus requires an emergent treatment as continuous epileptic activity results in increased pharmacoresistance, morbidity and mortality. Topiramate leads to a control of status epilepticus in 70% of the patients who showed no response to first-line treatments. As there are no parenteral formulations available, topiramate tablets are administered via enteral feeding tube. This is problematic in an emergency setting because pharmacokinetics are unpredictable and rapid therapeutic drug levels are essential.

Aim and Objectives The aim of this work is the development of a parenteral formulation of topiramate of 200 mg with a stability of at least 3 months to allow the production in a hospital pharmacy for a stock at the intensive care unit (ICU).

Material and Methods Due to poor solubility, different intravenous (IV) formulations were developed for stability and practicability testing: 4 mg/ml and 8 mg/ml with 0.025 M phosphate buffer as ready to use solutions and 20 mg/ml single dose vials with meglumine, a solubility enhancer. A stability study was conducted at time points 0 and 3 months evaluating the concentration of topiramate of three different batches with LC-MS, the pH, the clarity and colouring of the solution according to the European pharmacopoeia. The different formulations were tested during storage at room temperature and at 2–8°C.

Results All three formulations of topiramate (4 mg/ml, 8 mg/ml and 20 mg/ml) passed the stability requirements and exhibited a concentration of 100.7%, 101.2%, and 104.4% respectively after 3 months at room temperature and 106.3%, 101.7% and 99.5% respectively at 2–8 °C. There were no significant pH changes and the colour and clarity of the solution remained clear and colourless.

Conclusion and Relevance Our results are in line with Cloyd’s extrapolated stability data, that topiramate 7 mg/ml with 0.1M phosphate buffer is stable for 1.5 years at 5°C with a concentration of at least 90% topiramate. We demonstrated that topiramate parenteral solution is stable at room temperature for at least 3 months, which is favoured in a hospital setting. Therefore, the hospital pharmacy’s production unit can provide the ICU with a stock of an IV formulation of topiramate and the stability study will be continued.

Conflict of Interest No conflict of interest.