Opioid Analgesics Masserano Flashcards
(28 cards)
Integumental pain
Dermis, mucosa, muscle, joints, headache. Controlled by NSAIDs
Visceral pain
Pain within body cavities. . Best treated with opioids
Ascending pain pathway
Perception, localization and discrimination of pain
Descending pain pathway
Upper brain and brainstem use descending serotonin and norepinephrine neurons to reduce pain transmission through dorsal horn of the spinal cord
Spinal Cord Site of Action of Opioid Compounds
- ) Glutamate and nueropeptides
- ) Decrease Ca influx in the presynaptic neuron
- ) Increase K+ efflux in the postsynaptic neuron
- ) Decrease calcium influx by NE & 5HT
Morphine analgesia mechanism
- Raising the pain threshold at the spinal cord level
2. Altering the central nervous system perception of pain
Hyperalgesia
Persistent administration of opioid analgesics can increase the sensation of pain
Morphine euphoria mech
Mu agonists enhance DA release in nucleus accumbens and induce euphoria. Produces sense of well being
Morphine respiratory depression mech
Decreases response of brain stem respiratory neurons to CO2. Rate may fall 3 to 4 breaths per minute
Meperidine and Misosis
Does not develop with Meperidine and a choice narcotic for abuse by healthcare professionals
Morphine GI tract mech
- Decreases peristatic gut motility
- Increasing tone (persistent contraction)
Antidiarrheal w/ loperamide
Relistor MOA
Selective mu-opioid receptor that doesn’t cross BBB to relieve OIC
Eluxadoline (Viberzi)
New drug for IBS with diarrhea.
Mu and kappa receptor agonist/Delta receptor antagonist
Only modestly effective and very expensive
Morphine Urinary retention mech.
- Inhibits urinary voiding reflex
- Increases the tone of the external sphincter
- Water retention by increasing ADH and decreasing blood pressure
Morphine histamine release mech.
Causes mast cell degranulation with the release of histamine. Itching and diaphoresis common. Can be reversed by antihistamines
Hormonal actions of chronic therapy or abuse
- Decreased LH and FSH
- Decreased testosterone
- Decreased estrogen
Morphine for LV heart failure mech
- Reduces preload and afterload leading to a decrease in myocardial oxygen consumption
- Relieves the dyspnea associated with pulmonary edema due to LV failure
Mepergan (meperidine + promethazine)
Preanesthetic medication when analgesia, sedation, and anti-nausea are indicated.
Meperidine lil tid bits
- Less smooth muscle spasms, constipation, and depression of cough reflex.
- No miosis
- Tachycardia (most cause brady)
- Strong agonist
Codeine analgesia mech
Bioactivation 10% of codeine to morphine by CYP2D6.
Apomorphine MOA
- Little analgesic activity
- D2 receptor agonist that induces vomiting by direct action on the chemoreceptor trigger zone
Pentazocine (Talwin)
- Weak mu antagonist or partial agonist
- Blocks morphine analgesia and induces opioid withdrawal
- Agonist at kappa and sigma receptors
Butrophanol (Stadol)
- Anestheia and post-op analgesia
- Mu antagonist and Kappa agonist
Buprenorphine
Partial agonist at mu receptors with high affinity and slow dissociation
-Replacement for methadone as maintenance for opioid use disorder
