Pain Drugs Flashcards
What is the #1 pharmacological treatment for somatic (as opposed to neuralgic) Pain?
OTC Non-Opioid Analgesics
NSADIS, ASA, Acetaminophen, Cox-2 Inhibitors
Non-Opioid Analgesics:
MOA
Uses (5)
Targets the inflammatory component of pain cascade
Tx:
- Mild-moderate pain, esp somatic
- Soft tissue injury
- Strains/ Sprains
- HA
- Arthritis
* Can be used synergistically with opioids
Acetaminophen:
Side effects and contraindications
SE: Hepatotoxic, #1 cause of liver failure in US
CI: Liver disease, Alcoholics
NSAIDS + ASA:
Side effects and contraindications
SE: Gastric ulcers, Inhibit platelet agg.
CI: Don’t mix NSAIDS w/ ASA in pts on Cardioprotective ASA
Don’t give NSAIDs in third trimester of pregnancy
Opioid Agonist Drugs:
MOA (5)
- Activate inward K+ channels
- Inhibit Ca++ channels
- Inhibit adenylyl cyclase
- Inhibit release of substance P
- Synaptic remodeling by MAP kinase
* All work the same
Where are u receptors located? (3)
- CNS
(neocortex, amygdala, thalamus, n. accumbens, hippocampus) - Myenteric plexus (GI)
- Vas Deferens
What are the physiological effects of opioid action at u receptors? (5)
- Supraspinal analgesia
- Miosis
- GI stasis
- Respiratory depression
- Euphoria, dependence
Selective endogenous activators of u receptors (3)
- Endomorphin-1 & 2
- Enkephalins
- Beta-endorphin
2 important selective u ANTAGONISTS
- Naloxone
2. Naltrexone
Where are the K receptors located? (5)
Only in CNS
- Cerebral cortex
- Nucleus Accumbens
- Claustrum
- Hypothalamus
- SC
What are the physiological effects of activating the K receptors?
- SC analgesia
- Miosis
- Sedation
What is the endogenous activator of K receptors?
Dynorphins
What are 6 selective drug AGONISTS of u receptors?
- Morphine
- Fentanyl
- Methadone
- Meperidine
- Oxycodone
- Hydromorphone
What are 3 selective drug agonists of K receptors?
- Butorphanol
- Pentazocine
- Nalbuphine
What is the ultimate effect of long term opioid use on the nervous system?
Synaptic remodeling
Morphine:
Classification
MOA (2)
Therapeutic Use (3)
C: Strong agonist MOA: *Strongest agonist of u receptors *Agonist of K receptors in spinal cord only Uses: *Moderate to severe acute or chronic pain 1. Acute pulm. edema 2. MI pain 3. Preanesthetic
ROA for All Opioid Agonists (5)
- SQ
- IM
- oral
- suppository
- pump
ADR for all Opioid Agonists (4)
- Nausea, vomiting, constipation
- Miosis
- Respiratory Depression = OD
* Give ventilation + nalox - Tolerance- pain/ mood only, not above ADRs
NOT FIRST LINE DRUGS**
1 reason for death by opioid overdose
respiratory depression
Describe why opioid agonist possess abuse potential (esp. morphine)
u, K**agnonists–> euphoria/dysphoria–> abuse
How do opioid agonist (esp. morphine) induce n/v?
When is this important to consider?
Direct action on CTZ outside the BBB
*Must consider when administering morphine as pre-surgical analgesic so as to admin anti-emetic
How do we diagnose opioid intoxication?
Miosis ensues due to EW nucleus excitation; persists regards of light stimulation
*Pathogmonic
How do opioids like morphine induce respiratory depression?
Direct action on brainstem: decrease sensitivity to CO2
What is the most prominent GI side effect caused by opioid use?
Agonizing which receptors mediates this effect?
CONSTIPATION*
Mediated by u and delta activity
Name two antidiarrheal opioids with NO CNS activity
- Diphenoxylate
2. Loperamide (Immodium)
Describe 6 effects of opioid withdrawal
- Rebound phenomenon
- Hyperalgesia
- Hyperventilation
- Mydriasis
- Diarrhea
- Dysphoria
3 Drugs to NOT co-administer with opioids
- Phenothiazines
- MAOIs
- TCAs
3 Contraindications to opioid use
- Hepatic insufficiency
- Resp insufficiency
- Head injury