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Pain Types
- Nociceptive (somatic, visceral)
- Neuropathic (peripheral, central)
- Nociplastic (fibromyalgia, central sensitization)
WHO Ladder
- Step 1: non-opioid + adjuvant
- Step 2: weak opioid + non-opioid + adjuvant
- Step 3: strong opioid + non-opioid + adjuvant
NSAIDs Side Effects
- GI (PUD)
- Renal (AKI, sodium retention)
- CV (MI, stroke â esp coxibs except aspirin)
- Bleeding (antiplatelet)
Acetaminophen Dosing
- Max 4 g/d (3 g if liver disease)
- Hepatotoxicity overdose
Opioid Equivalence
- Morphine 30 mg PO = oxycodone 20 mg = hydromorphone 7.5 mg = fentanyl 12.5 ÎŒg/h patch
Opioid Side Effects
- Constipation (tolerance doesnât develop)
- Sedation, respiratory depression
- N/V
- Pruritus
- Hyperalgesia
- Hypogonadism
Naloxone
- For overdose
- 0.4-2 mg IV/IM
- Short half-life (re-narcotization possible)
Neuropathic Pain First-Line
- Gabapentin, pregabalin
- Duloxetine, venlafaxine
- TCAs (amitriptyline, nortriptyline)
Trigeminal Neuralgia
- Carbamazepine first-line
- Then oxcarbazepine, lamotrigine, gabapentin
- MVD (microvascular decompression)
Postherpetic Neuralgia
- Risk: age > 60, severe acute zoster, prodromal pain
- Prevention: Shingrix (recombinant zoster vaccine)
- Treatment: gabapentin, pregabalin, TCA, lidocaine patch
CRPS
- Type I (no nerve) + II (with nerve)
- Allodynia, autonomic, motor, trophic changes
- Multimodal â PT critical
- Sympathetic blocks
Drug Interactions
Tramadol
- Lowers seizure threshold
- Serotonin syndrome with SSRI/SNRI/MAOI
- CYP2D6 variability
Methadone
- QT prolongation
- Long T1/2 (accumulates)
- CYP interactions
- Useful for opioid-refractory neuropathic (NMDA)
TCA Side Effects
- Anticholinergic (dry mouth, urinary retention)
- Sedation
- Orthostasis
- QT prolongation
- Use at night, start low