Wallrock, William Charles - Non-inquest findings

Contributing factors

• inappropriate prescription of methadone to opioid-naïve ambulant patient by Dr T.
• methadone supplied from expired prescription originally issued to Dr T. for her own back pain
• high dose of methadone (70mg available, 50mg consumed over 30 hours)
• inconsistent written versus verbal dosing instructions
• undetected prior fluoxetine use; norfluoxetine metabolite prolonged methadone half-life by up to 75%
• high concurrent codeine consumption (560+ mg over 2-3 days) from multiple sources
• combination of codeine and methadone causing additive respiratory depression risk
• lack of optimization of initial appropriate analgesia (paracetamol and ibuprofen)
• multiple over-the-counter analgesics causing confusion about total drug exposure
• dental abscess with localized infection complicating recovery

Coroner's recommendations

1. Establish and enforce adherence to evidence-based guidelines for acute pain management following dental procedures (paracetamol and NSAIDs as first line, with optimization before addition of low-dose opioids such as codeine)
2. Strengthen awareness among prescribers of the inappropriateness of methadone for acute pain in ambulant, opioid-naïve patients due to unpredictable metabolism and overdose risk
3. Implement mandatory systems to screen for medication history (including antidepressants) and drug interactions, particularly when prescribing opioids
4. Ensure consistency between written and verbal medication instructions to avoid patient confusion
5. Prohibit supply of medications prescribed for a healthcare provider's own use to patients
6. Educate healthcare providers on the pharmacokinetic interactions between fluoxetine/norfluoxetine and opioids, particularly methadone
7. Advocate for patient education on cumulative drug exposure when multiple analgesics are being used concurrently