How to select painculars

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how to select pain medications analgesic ladder principles 2024

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How to Select Pain Medications

Selecting the right pain medication depends on several key factors: the type of pain, its severity, the underlying cause, and the patient's clinical profile. The most widely used framework is the WHO Analgesic Ladder, developed in 1986 and still the global standard.

Step 1 - Assess the Pain First

Before selecting any medication, properly characterize the pain. Key dimensions to evaluate:

Dimension	What to assess
Severity	Use Numeric Rating Scale (NRS): mild (1-3), moderate (4-6), severe (7-10)
Type	Nociceptive (somatic or visceral) vs. Neuropathic vs. Mixed
Duration	Acute vs. Subacute vs. Chronic
Pattern	Continuous vs. Breakthrough (incident, spontaneous, end-of-dose)
Location/Quality	Sharp, burning, cramping, aching, radiating

Nociceptive pain (from tissue damage) and neuropathic pain (from nerve damage) often require different drug classes. - Katzung's Basic and Clinical Pharmacology, p. 884

Step 2 - Use the WHO Analgesic Ladder

The WHO ladder guides selection based on pain severity - you start at the appropriate step, not always from the bottom.

Step 1 - Mild Pain (NRS 1-3): Non-Opioids

Paracetamol (acetaminophen) - first choice; low side-effect profile
NSAIDs (ibuprofen, naproxen, diclofenac) - especially for inflammatory/musculoskeletal pain
+/- Adjuvant drugs (see below)

Step 2 - Moderate Pain (NRS 4-6): Weak Opioids

Codeine, tramadol, low-dose oxycodone
Often combined with Step 1 agents (e.g., codeine + paracetamol)
+/- Adjuvants

Step 3 - Severe Pain (NRS 7-10): Strong Opioids

Morphine (oral or parenteral) - gold standard
Oxycodone, hydromorphone, fentanyl (patch for stable chronic pain)
For cancer/terminal illness: fixed-interval dosing (scheduled, not PRN) is more effective than on-demand dosing
+/- Adjuvants

A proposed Step 4 (interventional approaches) applies to the ~10-15% of patients with refractory severe pain: nerve blocks, neurolysis, intrathecal drug delivery.

Step 3 - WHO's 5 Principles for Giving Analgesics

By mouth - oral route preferred whenever possible for ease and consistency
By the clock - give on a regular schedule (not just when pain flares) to maintain steady analgesia
By the ladder - follow the stepwise progression based on severity
For the individual - titrate dose to the right level for each patient; no universal dose
With attention to detail - monitor closely, reassess regularly, adjust as needed

Cummings Otolaryngology, p. 296

Step 4 - Choose Based on Pain Type

Nociceptive Pain (somatic - bones, muscles, joints)

NSAIDs are particularly effective (anti-inflammatory)
Opioids for severe cases

Visceral Pain (organs)

Opioids (often needed)
Antispasmodics for colicky pain

Neuropathic Pain (burning, shooting, electric-shock quality)

First-line: Gabapentin, pregabalin (anticonvulsants)
First-line: Duloxetine, tricyclic antidepressants (TCAs like amitriptyline)
Opioids work but are less effective than for nociceptive pain
Adjuvants are often essential here

Step 5 - Select the Route of Administration

Route	When to use
Oral	Default; stable, cooperative patient
Transdermal (patch)	Stable chronic pain (e.g., fentanyl patch); unable to swallow
Parenteral (IV/IM/SC)	Acute severe pain; post-operative; when oral is unavailable
Neuraxial (epidural/intrathecal)	Severe refractory pain; post-surgical

For patients with head and neck cancers or dysphagia, alternative routes to the oral route must be considered. - Cummings Otolaryngology, p. 296

Adjuvant (Co-Analgesic) Drugs

These are not primarily analgesics but enhance pain relief - they should be added at any step of the ladder when appropriate:

Adjuvant class	Examples	Best for
Anticonvulsants	Gabapentin, pregabalin	Neuropathic pain
Antidepressants	Amitriptyline, duloxetine	Neuropathic, chronic pain
Corticosteroids	Dexamethasone	Inflammatory pain, bone pain
Bisphosphonates	Zoledronic acid	Bone metastasis pain
Muscle relaxants	Baclofen	Muscle spasm pain
Topical agents	Lidocaine patch, capsaicin	Localized neuropathic pain

Special Considerations

Chronic non-cancer pain: Use multimodal strategies; evidence for long-term opioids (>3-6 months) is weak - non-pharmacological approaches (physiotherapy, CBT, exercise) are important
Cancer pain: More aggressive use of opioids is appropriate; quality of life is the priority
Elderly patients: Start low, go slow; avoid NSAIDs (renal/GI risk); beware of sedation
Renal/hepatic impairment: Avoid NSAIDs; adjust opioid doses; gabapentin needs renal dose adjustment
Breakthrough pain: Add short-acting ("rescue") doses on top of long-acting background medication; typically 10-15% of the total daily dose
Sustained-release formulations (e.g., MS Contin, OxyContin) provide more stable analgesia for chronic pain but are not superior for acute or short-term use

Summary Algorithm

Assess pain severity (NRS) + type (nociceptive vs. neuropathic)
        |
  Mild (1-3)        Moderate (4-6)        Severe (7-10)
  Paracetamol/      Weak opioid           Strong opioid
  NSAIDs            + non-opioid          (morphine etc.)
        |                 |                     |
        +------ Add adjuvants if neuropathic ----+
        |
  Reassess frequently - titrate up/down - use by-the-clock dosing

The key principle: establish clear analgesic goals before starting, monitor effectiveness frequently, and adjust the plan - medication selection is a dynamic process, not a one-time decision. - Katzung's Basic and Clinical Pharmacology, p. 884

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