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| office_hours:pain:start [2026/02/14 17:13] – [Guiding Clinical Principles] andrew2393cns | office_hours:pain:start [2026/02/15 03:28] (current) – andrew2393cns |
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| ====== Pain Management Series ====== | {{ :office_hours:series:pain.png?400 |}} |
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| {{:pharmatlas:pain_management_banner.jpg?nolink&1200x250}} | |
| ===== Overview ===== | ===== Overview ===== |
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| ===== V. Pharmacologic Drug Classes ===== | ===== V. Pharmacologic Drug Classes ===== |
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| Pain pharmacotherapy must match mechanism. | Pain pharmacotherapy must match mechanism. This series will cover the drugs that can be used for pain |
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| This series will cover the following drug classes: | See: [[pain_management:drug_classes|Pain Pharmacotherapy]] |
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| ---- | |
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| ==== Anti-Inflammatory Agents ==== | |
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| * [[cardio:anti_inflammatory:nsaids|NSAIDs]] | |
| * [[endocrine:corticosteroids|Corticosteroids]] | |
| * [[pain_management:acetaminophen|Acetaminophen]] | |
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| Mechanism: | |
| Decrease prostaglandin-mediated sensitization. | |
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| ---- | |
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| ==== Voltage-Gated Sodium Channel Antagonists ==== | |
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| * [[neuro:local_anesthetics|Lidocaine]] | |
| * Suzetrigine (Nav 1.8 selective antagonist) | |
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| Mechanism: | |
| Block action potential propagation in nociceptors. | |
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| ---- | |
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| ==== Gabapentinoids ==== | |
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| * [[neuro:anticonvulsants|Gabapentin]] | |
| * [[neuro:anticonvulsants|Pregabalin]] | |
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| Mechanism: | |
| Bind α2δ calcium channel subunit → decrease glutamate & substance P release. | |
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| ---- | |
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| ==== Serotonin & Norepinephrine Reuptake Inhibitors ==== | |
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| * [[psychiatry:snri|SNRIs]] | |
| * [[psychiatry:tca|Tricyclic Antidepressants (TCAs)]] | |
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| Mechanism: | |
| Enhance descending inhibitory pathways. | |
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| ---- | |
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| ==== NMDA Receptor Antagonists ==== | |
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| * [[neuro:nmda_antagonists|Ketamine]] | |
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| Mechanism: | |
| Reduce central sensitization and wind-up. | |
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| ---- | |
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| ==== Opioid Analgesics ==== | |
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| * [[controlled_substances:opioids|Opioids]] | |
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| Mechanism: | |
| μ-receptor activation → decrease ascending pain transmission. | |
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| ---- | |
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| ==== NK1 Receptor Antagonists (Investigational for Pain) ==== | |
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| * [[gi:antiemetics:nk1_antagonists|NK1 Antagonists]] | |
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| Mechanism: | |
| Block Substance P at NK1 receptors. | |
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| Clinical role in chronic pain remains limited. | |
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| ---- | |
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| ==== Nerve Growth Factor (NGF) Antibodies ==== | |
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| * Tanezumab | |
| * Fasinumab | |
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| Mechanism: | |
| Block NGF-mediated nociceptor sensitization. | |
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| Not currently approved due to safety concerns. | |
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| ---- | |
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| ==== Cannabinoids ==== | |
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| * THC | |
| * CBD | |
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| Mechanism: | |
| CB1/CB2 receptor modulation (evidence evolving). | |
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| ---- | ---- |
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| <WRAP round important 80%> | <WRAP round important 80%> |
| • Pain classification determines therapy | * • Pain classification determines therapy |
| • Chronic pain often reflects central amplification | * • Chronic pain often reflects central amplification |
| • Mechanism-directed prescribing improves outcomes | * • Mechanism-directed prescribing improves outcomes |
| • Opioids are powerful but limited tools | * • Opioids are powerful but limited tools |
| • Multimodal therapy reduces risk | * • Multimodal therapy reduces risk |
| </WRAP> | </WRAP> |
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| ---- | ---- |
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| ===== Pharm Reference: Pain Drug Reference (Mechanism → Best Use) ===== | |
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| ^ Class ^ Drug ^ Primary Pain Type(s) ^ Acute vs Chronic ^ Best Clinical Use ^ Key Pearls / Major Cautions ^ | |
| | [[cardio:anti_inflammatory:nsaids|NSAIDs]] | [[cardio:anti_inflammatory:ibuprofen|Ibuprofen]] | Nociceptive (somatic), inflammatory | Acute + Chronic | MSK pain, OA flares | GI/renal risk; ↑BP; avoid in CKD/dehydration; ceiling effect | | |
| | [[cardio:anti_inflammatory:nsaids|NSAIDs]] | [[cardio:anti_inflammatory:naproxen|Naproxen]] | Nociceptive, inflammatory | Acute + Chronic | OA, tendinitis | Similar NSAID risks; longer duration | | |
| | [[cardio:anti_inflammatory:nsaids|NSAIDs]] | [[cardio:anti_inflammatory:diclofenac|Diclofenac]] | Nociceptive, inflammatory | Acute + Chronic | OA (esp topical) | Higher CV risk; topical has less systemic exposure | | |
| | [[cardio:anti_inflammatory:nsaids|NSAIDs]] | [[cardio:anti_inflammatory:indomethacin|Indomethacin]] | Nociceptive, inflammatory | Acute | Acute gout/indomethacin-responsive pain | More CNS/GI adverse effects vs many NSAIDs | | |
| | [[cardio:anti_inflammatory:nsaids|NSAIDs]] | [[cardio:anti_inflammatory:celecoxib|Celecoxib]] | Nociceptive, inflammatory | Acute + Chronic | OA/RA, GI-risk patients | COX-2 selective → less GI ulcer risk; still CV/renal risk | | |
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| | [[pain_management:acetaminophen|Acetaminophen]] | [[pain_management:acetaminophen|Acetaminophen]] | Nociceptive (mild), fever/pain | Acute + Chronic | Baseline analgesic, combination therapy | Liver toxicity risk; safer in CKD than NSAIDs; ceiling effect | | |
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| | [[endocrine:corticosteroids|Corticosteroids]] | [[endocrine:prednisone|Prednisone]] | Inflammatory pain syndromes | Acute (bursts) | Radiculitis flares, inflammatory pain | Not an analgesic; treat inflammation; hyperglycemia, mood, BP | | |
| | [[endocrine:corticosteroids|Corticosteroids]] | [[endocrine:methylprednisolone|Methylprednisolone]] | Inflammatory | Acute | Dose packs/flares | Same steroid cautions; short courses preferred | | |
| | [[endocrine:corticosteroids|Corticosteroids]] | [[endocrine:dexamethasone|Dexamethasone]] | Inflammatory, cancer-related edema pain | Acute | Severe inflammation/edema | Potent/long acting; insomnia, hyperglycemia | | |
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| | [[neuro:sodium_channel_blockers|Na+ Channel Antagonists]] | [[neuro:local_anesthetics:lidocaine|Lidocaine]] | Neuropathic (localized), nociceptive (procedural) | Acute + Chronic | Topical neuropathic pain; procedures; patches | Topical helpful in PHN; systemic toxicity if misused | | |
| | [[neuro:sodium_channel_blockers|Na+ Channel Antagonists]] | [[pain_management:drugs:suzetrigine|Suzetrigine]] | Nociceptive (acute), mixed (emerging) | Acute (primary) | Oral peripheral analgesia (Nav1.8) | Newer agent; keep as “emerging/updates” section | | |
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| | [[neuro:anticonvulsants|Antiepileptics]] | [[neuro:gabapentin|Gabapentin]] | Neuropathic, mixed | Chronic (± acute adjunct) | DPN, PHN, radicular neuropathic pain | Sedation/dizziness; dose adjust CKD; misuse risk | | |
| | [[neuro:anticonvulsants|Antiepileptics]] | [[neuro:pregabalin|Pregabalin]] | Neuropathic, nociplastic (some) | Chronic | DPN, PHN, fibromyalgia | Faster onset than gabapentin; CKD dose adjust; edema | | |
| | [[neuro:anticonvulsants|Antiepileptics]] | [[neuro:carbamazepine|Carbamazepine]] | Neuropathic (paroxysmal) | Chronic | Trigeminal neuralgia | Hyponatremia; CBC/LFT monitoring; drug interactions | | |
| | [[neuro:anticonvulsants|Antiepileptics]] | [[neuro:oxcarbazepine|Oxcarbazepine]] | Neuropathic (paroxysmal) | Chronic | Trigeminal neuralgia alt | Hyponatremia; fewer interactions than carbamazepine | | |
| | [[neuro:anticonvulsants|Antiepileptics]] | [[neuro:lamotrigine|Lamotrigine]] | Neuropathic (selected) | Chronic | Selected neuropathic syndromes | Rash/SJS risk; slow titration | | |
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| | [[psychiatry:snri|SNRIs]] | [[psychiatry:duloxetine|Duloxetine]] | Neuropathic + nociplastic + chronic MSK | Chronic | DPN, fibromyalgia, chronic back pain/OA pain | Nausea, BP; avoid severe liver disease; taper to stop | | |
| | [[psychiatry:snri|SNRIs]] | [[psychiatry:venlafaxine|Venlafaxine]] | Neuropathic (some) | Chronic | Neuropathic pain alt | BP/withdrawal; dose-dependent NE effects | | |
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| | [[psychiatry:tca|TCAs]] | [[psychiatry:amitriptyline|Amitriptyline]] | Neuropathic + nociplastic | Chronic | Neuropathic pain, sleep-pain overlap | Anticholinergic/QTc; avoid elderly/high fall risk | | |
| | [[psychiatry:tca|TCAs]] | [[psychiatry:nortriptyline|Nortriptyline]] | Neuropathic + nociplastic | Chronic | Neuropathic pain with fewer side effects than amitriptyline | Still anticholinergic/QTc; start low, go slow | | |
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| | [[neuro:nmda_antagonists|NMDA Antagonists]] | [[neuro:ketamine|Ketamine]] | Hyperalgesia, severe acute pain; CRPS (selected) | Acute/episodic | Opioid-refractory pain, ED/procedural | Dissociation/HTN; protocols; not routine outpatient | | |
| | [[neuro:nmda_antagonists|NMDA Antagonists]] | [[controlled_substances:methadone|Methadone]] | Mixed, neuropathic component (via NMDA) | Chronic (specialist) | Chronic severe pain; OUD overlap | QTc; complex kinetics; high interaction burden | | |
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| | [[controlled_substances:opioids|Opioids]] | [[controlled_substances:morphine|Morphine]] | Nociceptive (severe), cancer pain | Acute + Chronic (selected) | Severe acute pain, palliative/cancer | Constipation/resp depression; avoid in CKD (active metabolites) | | |
| | [[controlled_substances:opioids|Opioids]] | [[controlled_substances:oxycodone|Oxycodone]] | Nociceptive (severe) | Acute + Chronic (selected) | Severe acute pain | High misuse risk; constipation; taper planning | | |
| | [[controlled_substances:opioids|Opioids]] | [[controlled_substances:hydrocodone|Hydrocodone]] | Nociceptive (moderate-severe) | Acute | Short-term acute pain | Often combo APAP → watch total APAP dose | | |
| | [[controlled_substances:opioids|Opioids]] | [[controlled_substances:fentanyl|Fentanyl]] | Severe nociceptive; periop | Acute (mostly) | OR/ICU; chronic patches in opioid-tolerant | Patch only opioid-tolerant; fatal if misused | | |
| | [[controlled_substances:opioids|Opioids]] | [[controlled_substances:buprenorphine|Buprenorphine]] | Mixed; chronic pain with safety advantages | Chronic | Pain + OUD overlap; safer respiratory profile | Partial agonist; precipitated withdrawal risk; specialist comfort | | |
| | [[controlled_substances:opioids|Opioids]] | [[controlled_substances:tramadol|Tramadol]] | Mixed (nociceptive + monoaminergic) | Acute/Chronic (selected) | Short courses; selected chronic | Seizure risk; serotonin syndrome; variable metabolism | | |
| | [[controlled_substances:opioids|Opioids]] | [[controlled_substances:tapentadol|Tapentadol]] | Mixed; neuropathic component | Acute + Chronic (selected) | Severe pain with neuropathic component | μ + NE reuptake; still opioid risks | | |
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| | [[neuro:alpha2_agonists|Alpha-2 Agonists]] | [[cardio:clonidine|Clonidine]] | Neuropathic adjunct; withdrawal-related pain | Acute/adjunct | Adjunct analgesia; periop; sympathetic-driven pain | Hypotension/bradycardia; rebound HTN if abrupt stop | | |
| | [[neuro:alpha2_agonists|Alpha-2 Agonists]] | [[pain_management:drugs:dexmedetomidine|Dexmedetomidine]] | Acute analgesic-sparing (ICU/periop) | Acute | ICU sedation w/ analgesic sparing | Bradycardia/hypotension; monitored settings | | |
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| | [[pain_management:muscle_relaxants|Muscle Relaxants]] | [[neuro:cyclobenzaprine|Cyclobenzaprine]] | Acute MSK spasm pain | Acute | Acute back/neck spasm | Sedating/anticholinergic; avoid elderly | | |
| | [[pain_management:muscle_relaxants|Muscle Relaxants]] | [[neuro:tizanidine|Tizanidine]] | Spasticity-related pain; MSK spasm | Acute/Chronic | Spasm/spasticity | Hypotension/sedation; CYP1A2 interactions | | |
| | [[pain_management:muscle_relaxants|Muscle Relaxants]] | [[neuro:baclofen|Baclofen]] | Spasticity pain | Chronic | Neuro spasticity | Withdrawal if abrupt stop; sedation | | |
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| | [[pain_management:topical_agents|Topical Analgesics]] | [[neuro:local_anesthetics:lidocaine|Topical Lidocaine]] | Neuropathic (localized) | Chronic | PHN, focal neuropathic pain | Low systemic risk; site reactions | | |
| | [[pain_management:topical_agents|Topical Analgesics]] | [[pain_management:drugs:capsaicin|Capsaicin]] | Neuropathic (localized), some nociplastic | Chronic | Peripheral neuropathic pain | Burning initially; adherence barrier | | |
| | [[pain_management:topical_agents|Topical Analgesics]] | [[cardio:anti_inflammatory:diclofenac|Topical Diclofenac]] | Nociceptive inflammatory | Acute + Chronic | OA localized joints | Lower systemic risk than oral NSAIDs | | |
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| | [[neuro:triptans|Triptans]] | [[pain_management:drugs:sumatriptan|Sumatriptan]] | Migraine/headache syndromes | Acute | Abort migraine | Contra CAD/uncontrolled HTN; medication overuse | | |
| | [[neuro:triptans|Triptans]] | [[pain_management:drugs:rizatriptan|Rizatriptan]] | Migraine/headache | Acute | Abort migraine | Same triptan cautions | | |
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| | [[neuro:cgrp_antagonists|CGRP Antagonists]] | [[pain_management:drugs:ubrogepant|Ubrogepant]] | Migraine/headache | Acute | Abort migraine | No vasoconstriction; CYP interactions | | |
| | [[neuro:cgrp_antagonists|CGRP Antagonists]] | [[pain_management:drugs:rimegepant|Rimegepant]] | Migraine/headache | Acute (± prevention depending use) | Abort migraine | Useful when triptans contraindicated | | |
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| | [[neuro:botulinum_toxin|Botulinum Toxin]] | [[pain_management:drugs:onabotulinumtoxina|OnabotulinumtoxinA]] | Chronic migraine | Chronic | Prevention (chronic migraine) | Procedure-based; q12 weeks typical | | |
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| | [[gi:antiemetics:nk1_antagonists|NK1 Antagonists]] | [[gi:antiemetics:aprepitant|Aprepitant]] | Investigational (pain) | N/A | Primarily antiemetic; pain research only | Not established analgesic clinically | | |
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| | [[pain_management:ngf_antibodies|NGF Antibodies]] | [[pain_management:drugs:tanezumab|Tanezumab]] | Nociceptive (OA) | Chronic | OA pain (investigational/limited) | Safety concerns (joint damage); not routine | | |
| | [[pain_management:ngf_antibodies|NGF Antibodies]] | [[pain_management:drugs:fasinumab|Fasinumab]] | Nociceptive (OA) | Chronic | OA pain (investigational/limited) | Similar concerns; evolving status | | |
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| | [[pain_management:cannabinoids|Cannabinoids]] | [[pain_management:drugs:thc|THC]] | Neuropathic (modest), mixed | Chronic (selected) | Adjunct in selected chronic pain | Cognition/anxiety; variability; safety/legal issues | | |
| | [[pain_management:cannabinoids|Cannabinoids]] | [[pain_management:drugs:cbd|CBD]] | Mixed (variable evidence) | Chronic (selected) | Adjunct | Interaction potential; product variability | | |
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| <WRAP round important 90%> | |
| **Quick interpretation:** | |
| • **Nociceptive pain** → NSAIDs/APAP ± short opioid course; topical NSAID for localized OA | |
| • **Neuropathic pain** → gabapentinoids, SNRIs, TCAs, Na+ blockers; opioids often weak long-term | |
| • **Nociplastic pain** → SNRIs/TCAs + exercise/sleep; avoid chronic opioids when possible | |
| • **Migraine/headache** → triptans/gepants acute; botox prevention for chronic migraine | |
| </WRAP> | |
