Background Nystatin is often used in the treatment of cutaneous, vaginal, mucosal and oesophageal Candida infections. It’s widely employed in cancer and immunocompromised patients suffering from mucositis.

The unobtainability of the commercial oral suspension from July 2011 to February 2012 caused difficulties in the provision of the medicine for these types of inpatients and outpatients.

Purpose With the aim of ensuring a safe continuity of treatment, liquid formulations of nystatin 100,000 IU/ml were developed as oral suspensions, due to the insolubility of the drug in water. The suspensions obtained were studied to assess their chemical-physical stability to find the most suitable formulation.

Materials and Methods Nystatin was dispersed in water containing preservative using carboxymethyl cellulose (CMC) or tragacanth gum as suspending agents. The aqueous vehicles used were sucrose syrup or sorbitol syrup (for the treatment of diabetic or paediatric patients) flavoured with raspberry flavour. The final pH was maintained in the 7.0–7.8 range. The suspensions obtained were submitted to stability studies determining their chemical-physical properties (mean particle sizes, viscosity, Zeta potential) and the active ingredient content (HPLC analysis) over a 3-month period.

Results Stable suspensions of nystatin were obtained with mean sizes slightly greater than 1 μm, with both suspending agents and vehicles. CMC and sucrose syrup-containing suspension, however, was more resistant to microbiological attack and it was chosen as the most suitable preparation. Particle sizes, Zeta potential and viscosity remained unchanged for at least 3 months at 25 and 40°C. The nystatin content in the suspension decreased by about 16% after the first month and then remained constant over time.

Conclusions The development of a stable nystatin suspension was crucial to ensure continuity of care for patients with oral mucositis previously treated with a commercial formulation, whose temporary lack offered new formulation challenges to the hospital pharmacists.

No conflict of interest.