Review 3 Flashcards
Capsaicin
VR-1 agonist
Repeated application thought to deplete substance P from primary afferent pain neurons (cream)
Adverse Reactions: Burning, stinging, and erythema at the site of application
Ketamine
Glutamate antagonist at NMDA receptors in ascending pain pathway blocking acute nociceptive pain
Prevents central sensitization process in chronic pain
Low back pain
TCADs
Fibromyalgia
SNRIs
Topical local anesthetic
lidocaine
VSCC α2δ ligands
pregabalin - gabapentin
Nonopioid analgesics
NSAIDs, acetaminophen, COX-2 selective, aspirin
Acute neuropathic pain
Neuropathic cancer pain
Episodic exacerbations of severe pain
Opioid analgesics may be used
Chronic Mild pain
non-opioid, adjuvants useful
↓ central sense, perf sense, ↑ descending inhibition
Nothing works better than ____ for inflamtions
glucocorticoids
Nothing works better than____ for pain
Opioids
Multimodal spare:
Opioid sparing
What is Multimodal Analgesia?
Use of multiple classes of analgesics acting via different pathways
Opioid monotherapy remains a cornerstone of treatment for severe postoperative pain BUT idiosyncratic and dose-limiting side effects curtail practical efficacy
Benefits of combining other agents with opioids
Greater analgesic efficacy from synergistic actions of agents with different mechanisms
Synergism between agents allows use of lower doses (“opioid-sparing”) limiting dose-related side effects
Agonists at u-opioid receptors modulate
Transmission of pain (dorsal horn)
Perception - reaction to pain (cortex -limbic system)
Mainstay of therapy for moderate-to-severe acute pain
Opiods
NOTE: Use of non-opioid and adjuvant medications is emphasized for treatment of chronic-persistent pain
Opioids - Side Effects
NV
Constipation
Pruritus
resp depression serious, reverse with naloxone
monitor sedation
Opioids - Side Effects Constipation
Tolerance to constipation does not develop to same level as to analgesia or respiratory depression
Local Anesthetic Molecule INtermediate chain
Determines metabolic pathway and allergenicity
Local Anesthetic Molecule lipophilic ring
Penetration of bio membrane
Local Anesthetic Molecule hydrophilic R group
Ionizable amine - pH determines % of charged vs uncharged
Local Anesthetic- Influence of pH on Distribution
Equilibrium reaction between bases and protons (H+ ions) is written as acid dissociations (loss of proton)
R-NH3+ (blocking) R-NH2 (soluble) + H+
Nonionized form (R-NH2) predominates at higher pHs and more readily crosses neuronal membranes
Sodium Channel and Sites of LA Action
Use-dependent block [preferential binding to open and inactivated states] of Na+ channel by LA prevents propagation of action potential and transmission of pain impulses
Local Anesthetics Side effects
Neurotoxicity, hypotension, dizziness, drowsiness
NSAIDs – COX-2 Inhibitors
side affects
Side Effects:
GI ulceration (esp. ketorolac used in the elderly)
Increased bleeding risk
Renal dysfunction
COX-2 selective agents may increase CVS complications increased thrombotic risk
