WHO Analgesic Ladder — Pain Management
詳細ガイド 近日公開
WHO Analgesic Ladder Referenceの包括的な教育ガイドを準備中です。ステップバイステップの解説、数式、実例、専門家のヒントをお届けしますので、もうしばらくお待ちください。
The World Health Organization (WHO) Pain Relief Ladder is a three-step framework for cancer pain management, originally published by the WHO in 1986 as part of its global initiative to improve access to analgesic medicines for cancer patients worldwide. Despite being developed nearly four decades ago, the WHO ladder remains the foundational guideline for pharmacological pain management in oncology and palliative care, endorsed by major international societies including ESMO, EAPC, and NCCN. The ladder is based on the principle of stepwise analgesic escalation matched to pain severity, with the guiding concepts of 'by the mouth, by the clock, by the ladder, and for the individual.' Step 1 addresses mild pain (NRS 1–3): non-opioid analgesics including paracetamol (acetaminophen) and NSAIDs (ibuprofen, naproxen, diclofenac) with or without adjuvant analgesics. Step 2 addresses moderate pain (NRS 4–6): weak opioids such as codeine, tramadol, or low-dose oral morphine/oxycodone (some guidelines now advocate going directly to Step 3 for moderate pain). Step 3 addresses severe pain (NRS 7–10): strong opioids — morphine (gold standard), oxycodone, hydromorphone, fentanyl, or methadone — with or without non-opioids and adjuvants. Adjuvant analgesics are added at any step based on pain mechanism: tricyclic antidepressants and gabapentinoids for neuropathic pain; corticosteroids for inflammatory or oedematous pain; bisphosphonates for bone metastases pain; ketamine for refractory neuropathic pain. Route escalation follows a separate principle: oral route first, then subcutaneous, then intravenous. A fourth step (invasive interventions — nerve blocks, epidural analgesia, intrathecal drug delivery) is sometimes appended for refractory pain.
Step 1 (mild pain, NRS 1–3): Non-opioid ± adjuvant; paracetamol 500–1000 mg q4–6h (max 4 g/day); NSAID (e.g., ibuprofen 400–600 mg q8h); Step 2 (moderate pain, NRS 4–6): Weak opioid + non-opioid ± adjuvant; codeine 30–60 mg q4h; tramadol 50–100 mg q6–8h; Step 3 (severe pain, NRS 7–10): Strong opioid + non-opioid ± adjuvant; oral morphine 5–10 mg q4h (starting dose); titrate 25–50% per 24h until pain controlled; adjuvants: gabapentin 300–1800 mg/day, amitriptyline 10–75 mg nocte
- 1Perform a comprehensive pain assessment before initiating therapy: use a validated pain scale (NRS 0–10, VAS, BPI, ESAS); characterise the pain by type (nociceptive somatic, visceral, neuropathic), onset, severity, aggravating/relieving factors, and impact on function and quality of life.
- 2Identify the pain mechanism to guide adjuvant selection: neuropathic features (burning, shooting, electric shock-like, allodynia, hyperalgesia) indicate gabapentinoids or TCAs; inflammatory/oedematous pain responds to corticosteroids; bone pain from metastases responds to NSAIDs, bisphosphonates, and radiotherapy.
- 3Start at the appropriate ladder step based on pain severity: NRS 1–3 → Step 1; NRS 4–6 → Step 2 (or Step 3 directly in some guidelines); NRS 7–10 → Step 3. Do not make patients endure severe pain while stepping up through lower rungs.
- 4Prescribe analgesia 'by the clock': schedule regular dosing rather than PRN to maintain steady analgesic plasma levels and prevent pain breakthrough; add a separate PRN breakthrough dose (1/6 of the total 24-hour opioid dose) for incident pain or end-of-dose pain.
- 5Titrate opioid doses to effect: if a patient requires ≥3 breakthrough doses in 24 hours, increase the regular opioid dose by 25–50% of the total 24-hour dose; reassess pain score and side effects at 24–48 hours after each titration.
- 6Manage opioid side effects proactively: constipation is universal and requires prophylactic laxatives (e.g., senna + macrogol) from the first opioid dose; nausea may occur in the first 1–2 weeks (use haloperidol or metoclopramide); sedation and respiratory depression are dose-related and require dose reassessment.
- 7Consider route escalation when oral route is no longer feasible (dysphagia, vomiting, reduced consciousness): continuous subcutaneous infusion (CSC/syringe driver) using diamorphine (UK), morphine, or hydromorphone; IV opioid infusion in hospital; or transdermal fentanyl patches (72-hour patch, stable pain only) as an alternative to oral opioids.
Always prescribe a gastroprotective PPI (omeprazole 20 mg daily) with NSAIDs in cancer patients on corticosteroids or anticoagulants.
Paracetamol and NSAIDs act synergistically by different mechanisms; combined use provides superior analgesia with lower opioid requirements — this opioid-sparing effect is particularly valuable in oncology.
Approximately 10% of the population are poor metabolisers of codeine (CYP2D6 deficient) and do not convert it to morphine — tramadol or low-dose morphine may be a better choice in these patients.
Mixed nociceptive-neuropathic cancer pain requires a multimodal approach; adding a gabapentinoid targets the neuropathic component while the opioid addresses the nociceptive element.
Review after 24–48h: total 24h opioid use (regular + breakthrough) = new regular dose.
Morphine titration begins conservatively and is increased by 25–50% every 24–48h based on breakthrough use. The key principle is regular re-assessment and dose adjustment — not fear of opioids.
Subcutaneous diamorphine is used in UK practice; SC morphine or hydromorphone in other countries. Always recalculate PRN dose and start laxative via alternative route.
Route conversion requires knowing the equianalgesic ratios: oral morphine:SC morphine ≈ 2:1 (bioavailability 33%); oral morphine:SC diamorphine ≈ 3:1. Conversion should be conservative to avoid overdose.
Palliative care physicians use the WHO ladder as the framework for all cancer pain consultations, selecting pharmacological agents and doses based on pain severity and mechanism., representing an important application area for the Who Pain Ladder in professional and analytical contexts where accurate who pain ladder calculations directly support informed decision-making, strategic planning, and performance optimization
Oncology nurses use breakthrough dose calculations daily when managing inpatients on opioid titration protocols, adjusting PRN doses based on the previous 24-hour consumption., representing an important application area for the Who Pain Ladder in professional and analytical contexts where accurate who pain ladder calculations directly support informed decision-making, strategic planning, and performance optimization
General practitioners use the WHO ladder in community palliative care to manage the majority of cancer pain at home, prescribing oral morphine and fentanyl patches with palliative care team support.
WHO Essential Medicines List compilations are informed by the ladder — morphine appears as an essential medicine because of the WHO ladder's evidence base for cancer pain relief., representing an important application area for the Who Pain Ladder in professional and analytical contexts where accurate who pain ladder calculations directly support informed decision-making, strategic planning, and performance optimization
Pain management teams in resource-limited settings rely on the WHO ladder because it requires only widely available, inexpensive medications (paracetamol, codeine, oral morphine) to provide effective cancer pain relief., representing an important application area for the Who Pain Ladder in professional and analytical contexts where accurate who pain ladder calculations directly support informed decision-making, strategic planning, and performance optimization
Renal failure — morphine caution
{'title': 'Renal failure — morphine caution', 'body': 'Morphine-6-glucuronide (M6G), the active metabolite of morphine, accumulates in renal failure and causes severe sedation, respiratory depression, and myoclonus. Oxycodone should also be used with caution (oxymorphone accumulation). Preferred opioids in GFR <30 mL/min: fentanyl, buprenorphine, or hydromorphone at reduced doses. Palliative care specialist input is recommended for opioid prescribing in severe renal impairment.'}
Liver failure — opioid prescribing
{'title': 'Liver failure — opioid prescribing', 'body': 'Hepatic impairment reduces first-pass metabolism of oral opioids, increasing bioavailability and prolonging half-life. Start with 50% of the standard dose, extend dosing intervals, and avoid codeine (pro-drug requiring hepatic activation). Morphine and oxycodone can be used with dose reduction; fentanyl (minimal hepatic metabolism) is preferred in severe cirrhosis. Risk of hepatic encephalopathy is increased with all sedating medications.'}
Incident pain — breakthrough dosing strategy
{'title': 'Incident pain — breakthrough dosing strategy', 'body': 'Incident pain (pain triggered by specific activities — movement, dressing changes, procedures) is common in cancer patients and is often undermanaged. Rapid-onset transmucosal fentanyl products (fentanyl buccal tablet, sublingual spray, intranasal spray) have onset within 10–15 minutes and are preferred over oral immediate-release morphine (onset 30–60 minutes) for incident pain. Pre-emptive dosing 15–20 minutes before predictable pain-triggering activities is an effective strategy.'}
Total pain — non-pharmacological dimensions
{'title': 'Total pain — non-pharmacological dimensions', 'body': "Dame Cicely Saunders' concept of 'total pain' recognises that cancer pain has physical, psychological, social, and spiritual dimensions. Pharmacological management of physical pain alone is insufficient. Psychological support (CBT, anxiety management), social support (carer education, financial assistance), spiritual care, and occupational therapy (adaptive equipment, energy conservation) are integral to comprehensive cancer pain management."}
| WHO Step | Pain Severity (NRS) | Drug Class | Examples |
|---|---|---|---|
| Step 1 | 1–3 (mild) | Non-opioid ± adjuvant | Paracetamol 1g QDS; Ibuprofen 400 mg TDS; Naproxen 500 mg BD |
| Step 2 | 4–6 (moderate) | Weak opioid + non-opioid ± adjuvant | Codeine 30–60 mg q4h; Tramadol 50–100 mg q6h; Low-dose morphine 5 mg q4h |
| Step 3 | 7–10 (severe) | Strong opioid + non-opioid ± adjuvant | Morphine 5–30 mg q4h (titrate); Oxycodone; Hydromorphone; Fentanyl patch |
| Adjuvants (any step) | Any | Based on pain mechanism | Gabapentin/Pregabalin (neuropathic); Dexamethasone (oedema/bone); Bisphosphonates (bone) |
| Step 4 (informal) | Refractory | Interventional | Nerve block; epidural; intrathecal drug delivery; ketamine infusion; palliative sedation |
Should Step 2 of the WHO ladder be skipped?
Some contemporary guidelines (EAPC, ESMO 2018) suggest that moderate-to-severe cancer pain (NRS ≥5) can be managed with low-dose strong opioids (e.g., morphine 5–10 mg q4h) rather than weak opioids, effectively moving from Step 1 to Step 3 directly. Step 2 weak opioids have a ceiling effect and drug interactions; low-dose strong opioids may provide more predictable titration. However, Step 2 agents remain appropriate in resource-limited settings.
What is the opioid equianalgesic dose table?
Equianalgesic doses (oral morphine equivalents): oral morphine 10 mg = oral codeine 100 mg = oral tramadol 100 mg = oral oxycodone 6.7 mg = oral hydromorphone 2 mg = SC diamorphine 3 mg = SC morphine 5 mg = fentanyl patch 25 mcg/h ≈ oral morphine 60–90 mg/day. These are approximate conversions — always reduce the calculated dose by 25–30% when switching opioids (incomplete cross-tolerance).
How should breakthrough pain doses be prescribed?
Breakthrough (PRN) opioid dose = 1/6 of the total 24-hour opioid dose, given as immediate-release preparation, available every 1–2 hours as needed. If a patient requires ≥3 PRN doses in any 24-hour period, the regular (background) dose should be increased by the total amount of PRN doses taken. This is particularly important in the context of who pain ladder calculations, where accuracy directly impacts decision-making. Professionals across multiple industries rely on precise who pain ladder computations to validate assumptions, optimize processes, and ensure compliance with applicable standards. Understanding the underlying methodology helps users interpret results correctly and identify when additional analysis may be warranted.
What adjuvants are used for neuropathic cancer pain?
First-line: gabapentinoids (gabapentin 900–3600 mg/day in divided doses; pregabalin 150–600 mg/day); tricyclic antidepressants (amitriptyline 10–75 mg nocte). Second-line: SNRIs (duloxetine 60–120 mg/day); lidocaine infusions; ketamine infusions. For bone pain: dexamethasone, NSAIDs, bisphosphonates (zoledronate), denosumab. Corticosteroids are particularly useful for pain related to peritumoural oedema, capsular pain, or spinal cord compression.
How is constipation from opioids managed?
Opioid-induced constipation (OIC) is universal and does not develop tolerance — laxatives must be prescribed from the first opioid dose and continued throughout therapy. First-line: stimulant laxative (senna 15–30 mg nocte) ± osmotic laxative (macrogol/PEG); docusate for faecal softening; increase fluid and fibre if possible. For refractory OIC: methylnaltrexone SC (peripherally acting mu-opioid receptor antagonist that does not cross the blood-brain barrier and does not reverse central analgesia).
What is opioid rotation and when is it used?
Opioid rotation (switching from one strong opioid to another) is used when: analgesic efficacy is inadequate despite dose escalation; intolerable side effects develop (hallucinations, severe nausea, renal toxicity from morphine metabolite accumulation); or change of route is required. The conversion uses equianalgesic tables with a 25–30% dose reduction for incomplete cross-tolerance. Common switches: morphine → hydromorphone, oxycodone, or fentanyl.
Is opioid addiction a concern in cancer patients?
True addiction (psychological dependence with drug-seeking behaviour) is rare in cancer patients treated appropriately for pain, occurring in <1% in the absence of prior substance use disorder. Physical dependence (requirement for dose tapering on discontinuation) and tolerance (diminishing effect over time) are expected physiological adaptations, not addiction. Fear of addiction should not prevent appropriate opioid prescribing in cancer pain.
What is the role of fentanyl patches in cancer pain?
Transdermal fentanyl patches (12.5, 25, 50, 75, 100 mcg/h) are appropriate for stable, chronic cancer pain in patients with swallowing difficulties or poor oral absorption. They deliver fentanyl continuously over 72 hours. They are NOT suitable for acute pain titration, rapidly changing pain, or opioid-naive patients due to the delayed onset (12–24h) and prolonged offset (12–24h after removal). Dose equivalence: fentanyl 25 mcg/h patch ≈ oral morphine 60–90 mg/day.
プロのヒント
The WHO ladder's most important principle is regularity: analgesics must be given 'by the clock' at fixed intervals, not on demand. A patient who takes 5 mg morphine q4h regularly requires 30 mg/24h; if they also use 3 breakthrough doses of 5 mg each, the next day's regular dose should be increased to 45 mg/24h (divided into q4h doses of 7.5 mg). This systematic use of breakthrough consumption data is the most reliable method for titrating opioids in cancer pain.
ご存知でしたか？
When the WHO Pain Relief Ladder was published in 1986, morphine was unavailable or heavily restricted in over 120 countries. The WHO's 'Access to Controlled Medications Programme' — built around the pain ladder — has subsequently improved opioid availability in many low- and middle-income countries. Despite this progress, the International Narcotics Control Board estimates that over 80% of the world's population still lacks adequate access to opioid analgesics for pain and palliative care.
参考文献
- ›WHO Cancer Pain Relief — 2nd Edition (WHO, 1996)
- ›Caraceni A et al. — EAPC recommendations for opioid use in cancer pain (Lancet Oncol 2012)
- ›NCCN Guidelines — Adult Cancer Pain (v1.2024)
- ›Fallon M et al. — ESMO Clinical Practice Guidelines — Management of Cancer Pain (2018)
- ›Portenoy RK — Treatment of cancer pain (Lancet, 2011)