Answer
The empty prolonged-release matrix may remain visible after its active ingredients have been released; this is described in the product information.
Sources for this answer
- Oxycodone hydrochloride/Naloxone hydrochloride 10 mg/5 mg prolonged-release tablets — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.