Background: Commercial omeprazole paediatric mixtures are not available. The stability of omeprazole mixtures prepared from Probitor capsules or omeprazole powder has not been established. Aim: To determine the physicochemical stability of two omeprazole mixtures, prepared from Probitor capsules or omeprazole powder BP, over a 45-day period under refrigeration or at room temperature, shaken or unshaken. Method: Omeprazole 2 mg/mL mixtures were prepared using standard procedures by either emptying the contents of Probitor capsules or by adding omeprazole powder to preserved sodium bicarbonate 8.4% solution. Each formulation was stored in 100 mL amber glass bottles under refrigeration (2-8