10.3 Pain Management & Opioids

10.3 Pain Management & Opioids

Quick Answer: Start with non-drug care + non-opioids (paracetamol/NSAIDs when appropriate), add adjuvants for neuropathic pain, and reserve opioids for carefully selected indications with goals, review dates, and risk mitigation. Know paracetamol ceilings, NSAID organ risks, S8 controls, constipation prophylaxis, overdose + naloxone, and that neuropathic pain often needs amitriptyline, duloxetine or gabapentinoids rather than endless opioid escalation.

Pain is one of the most frequent community presentations. Intern Written items test whether you can match medicine to pain type, minimise harm, and comply with controlled-drug law while remaining patient-centred.

Modernised WHO-style analgesic approach

The classic WHO cancer pain ladder (non-opioid → weak opioid → strong opioid) is still a useful teaching scaffold, but modern practice for chronic non-cancer pain emphasises:

1. Assess pain type (nociceptive, neuropathic, nociplastic/mixed), severity, function, red flags, and psychosocial context.
2. Non-pharmacological care first-line or concurrent: activity pacing, physiotherapy, heat/cold, psychological strategies, sleep, weight management where relevant.
3. Non-opioid analgesics and disease-specific treatment of the cause.
4. Adjuvants for neuropathic features.
5. Opioids only when benefits are likely to outweigh harms, with defined goals (function, not only pain score), time-limited trials, and exit plans.

For acute severe pain (trauma, post-operative, cancer-related pain pathways), opioids may be appropriate earlier — the exam still expects risk counselling and legal compliance.

Paracetamol and NSAIDs — not “harmless basics”

Paracetamol

Effective for many mild–moderate pains and often preferred when NSAIDs are unsuitable. Risks centre on hepatotoxicity in overdose, in chronic supra-therapeutic dosing, and in high-risk hosts (malnutrition, chronic heavy alcohol use, interacting products with hidden paracetamol).

Counselling:

• State the maximum daily dose clearly (product-specific; many adult OTC products use 4 g/day as a traditional ceiling — check current labelling and AMH, and lower in risk groups as advised).
• Check combination products (cold/flu, opioid combinations) to avoid double-dosing.
• Suspect intentional or accidental overdose → urgent emergency referral; antidote pathways are time-critical in hospital.

NSAIDs

Examples: ibuprofen, naproxen, diclofenac, meloxicam, celecoxib (COX-2 selective). Useful for inflammatory pain but carry:

Prefer lowest effective dose and shortest duration; consider gastroprotection strategies when indicated by the prescriber.

Weak vs strong opioids — conceptual map

“Weak” opioids historically include codeine and tramadol (and related agents). They still cause sedation, constipation, dependence, and respiratory depression risk, especially with other CNS depressants. Tramadol has additional seizure and serotonergic risks.

Strong opioids include morphine, oxycodone, hydromorphone, fentanyl, methadone, buprenorphine (context-dependent), and others. High-yield counselling:

• Start low, go slow in opioid-naïve patients; beware cumulative sedation with benzodiazepines and alcohol.
• Tolerance and physical dependence are expected with continuous use; addiction/opioid-use disorder is a related but distinct risk requiring screening and careful supply.
• Modified-release products must not be crushed or chewed (dose dumping).
• Transdermal fentanyl is for opioid-tolerant patients in appropriate indications — dangerous if misused in naïve patients.
• Breakthrough vs background dosing concepts matter in palliative and acute settings.

S8 controls reminder

Many strong opioids are Schedule 8 (controlled drugs) in Australia. Interns must know the legal supply framework at high level (valid prescription requirements, quantity/interval scrutiny, jurisdiction-specific real-time monitoring, secure storage, recording, and forgery vigilance). If legal elements are incomplete, do not supply — clarify with the prescriber. Legal detail is reinforced in the schedules chapter; here the clinical exam point is that therapeutic intent never overrides S8 compliance.

Constipation prophylaxis

Opioid-induced constipation is common and persistent (tolerance to constipation is limited). Best practice anticipates it:

• Counsel on fluids, fibre, and mobility where suitable.
• Recommend or ensure a plan for stimulant ± softener laxatives as appropriate (e.g. senna with docusate patterns — check AMH).
• Do not wait until severe faecal loading develops.
• Red flags (absolute constipation with vomiting, severe abdominal pain) need medical assessment.

Overdose risk and naloxone

Opioid overdose: reduced consciousness, slow/shallow breathing, miosis, snoring/gurgling, blue lips. Immediate actions: call emergency services, support airway/breathing per first-aid training, and administer naloxone if available and indicated.

Pharmacy role in harm reduction:

• Educate patients and carers on not mixing opioids with alcohol/benzodiazepines.
• Discuss safe storage away from children and others.
• Support access to take-home naloxone programs where available and indicated (including people on high-dose opioids, history of overdose, or using opioids with other sedatives).
• Counsel that naloxone is temporary — emergency care is still required after response because opioids may outlast naloxone.

Multimodal and neuropathic approaches

Multimodal analgesia combines complementary mechanisms (e.g. paracetamol + NSAID ± regional techniques ± low-dose opioid ± adjuvant) to improve control and reduce opioid load.

Neuropathic pain agents (high-level)

Neuropathic pain (burning, shooting, allodynia) often responds poorly to opioids alone.

Titrate slowly; set expectations that benefit may be partial; review efficacy and adverse effects; avoid automatic long-term continuation without benefit.

Putting scenarios together

High-yield stems: chronic back pain escalated on oxycodone without functional goals; NSAID triple whammy in an older person; paracetamol combination product overdose risk; missing S8 prescription elements; constipation ignored for weeks; gabapentinoid + opioid + benzodiazepine sedation stack; tramadol + SSRI serotonin risk. Correct answers prioritise mechanism-matched therapy, harm reduction, and legal safety over reflexive opioid escalation.