Clinical Use of Paracetamol, Morphine, and Pethidine for Pain Management

Introduction to Pain Management Guidelines

• The American Geriatrics Society recommends paracetamol as first-line therapy for mild-to-moderate pain, with a maximum daily dose of 4g (or 3g for chronic use) 1, 2, 3
• The European Society for Medical Oncology suggests paracetamol as the mainstay of steps 1 and 2 of the WHO analgesic ladder, though evidence supporting its efficacy is limited 1, 5

Recommended Dosage and Administration

• The British Journal of Cancer recommends starting with paracetamol 1000mg every 6 hours (maximum 4g daily) for any mild-to-moderate pain 2, 3
• The Annals of Oncology suggest adding an NSAID (ibuprofen preferred) rather than exceeding paracetamol maximum dose if inadequate relief after 24-48 hours 6

Opioid Therapy

• The Annals of Oncology recommend morphine for moderate-to-severe pain requiring opioid therapy, with dosage individually titrated to balance adequate analgesia against adverse effects 1, 5, 7
• The Journal of the American Geriatrics Society suggests pethidine has a limited modern role due to accumulation of toxic metabolite normeperidine, shorter duration of action than morphine, and higher risk of adverse effects 3, 5, 7

Safety Considerations

• The American Geriatrics Society advises to never exceed 4g daily paracetamol (3g for chronic use, elderly, or liver disease) to avoid hepatotoxicity 4
• The Journal of the American Geriatrics Society recommends monitoring for respiratory depression, constipation, and endocrine effects (hypogonadism with chronic use) when using morphine 3, 4