Background Commercial presentations of oral thioguanine suitable for dosing in paediatric patients diagnosed with acute lymphoblastic leukaemia (ALL) are not available in our country. Therefore, paediatricians in our hospital requested the pharmacy department to develop an oral thioguanine compounded medicine.

Purpose To develop a standard operating procedure (SOP) for an oral thioguanine compounded medicine suitable for treating paediatric patients diagnosed with ALL.

Material and methods In order to establish the most suitable formulation characteristics (composition, elaboration methods, stability, packaging materials and storage conditions) a bibliographic review of several databases was done (PubMed and Micromedex Health-Care). This research also included Trissel’s Stability of Compounded Formulations Paediatric Dosage Handbook and several paediatric hospital websites.

Results Based on the results, an SOP was designed to prepare a thioguanine suspension, in accordance with the general procedure for preparation of suspensions (PN/L/FF/008/00) of the National Formulary.

• Name: thioguanine 40 mg/mL suspension, 20 mL.

• Ingredients: thioguanine (800 mg; thioguanine 40 mg tablets are used), sterile water for irrigation (4 mL), methylcellulose 1% (7 mL), simple syrup (qs 20 mL).

• Equipment needed: 5 mL, 10 mL and 20 mL syringes, beaker, stir bar, plugs.-Packaging: amber glass prescription bottle.

• Modus operandi: suspension is prepared in a biological safety cabinet. The required volume of sterile water, methylcellulose and simple syrup is loaded into separate syringes and placed inside the cabinet, along with a 20 mL empty syringe and thioguanine tablets. Thioguanine is dissolved in water (without triturating the tablets, it could take between 15–20 min). Once completely dissolved, methylcellulose is added and stirred gently. This suspension is loaded into the empty syringe and diluted to 20 mL with simple syrup. The suspension is transferred to the prescription bottle and then properly shaken. The final suspension has a light yellow colour and pleasant organoleptic characteristics.

• Labelling: 40 mg/mL thioguanine suspension (20 mL). Administration: oral. Conservation: ambient temperature, protected from light. Shelf-life: 30 days. Shake before use.

• Indication: acute lymphoblastic leukaemia

Conclusion The SOP for the preparation of thioguanine 40 mg/mL oral suspension is simple and the designed compounded medicine has allowed the administration of the required dose, covering the therapeutic needs of paediatric patients diagnosed with ALL.

No conflict of interest.