Reduction of oral liquid controlled drugs discrepancy in day-to-day practice

Objectives: The storage, use and disposal of controlled drugs (CDs) in hospitals and other healthcare centres are governed by a combination of government legislation and local policy. In the UK, a running balance must be kept for Schedule 2 CDs and when discrepancies arise, they must be investigated and reconciled. Policies on acceptable discrepancies are varied and based on anecdotal evidence. This study was designed to simulate dosing and stock check procedures for oxycodone oral solution, as a sample CD solution, and evaluate where the volume losses that cause discrepancies could arise from.

Methods: Hypromellose solutions were formulated to simulate oxycodone commercial solutions. These were used to simulate dosing and stock check practices. Quantification of volume loss during simulated routine dosing and stock check of viscous oral CD formulations were performed in triplicate.

Key findings: Dosing with enteral syringes via a fitted rubber bung never resulted in volume loss. Volume loss was always observed during stock checks with no statistical difference between methods used.

Conclusions: The findings of this study support the following recommendations. Hospital pharmacy departments should provide oxycodone and other CD liquid formulation bottles pre-fitted with a bung and make sure personnel use enteral syringes that are compatible with the chosen adaptor and of the most appropriate size for the intended dose. Stock checks should be limited to the minimum required by law or local policy.