Opiates Flashcards
A class of naturally occurring, nitrogen-containing bases
-Ex: morphine, cocaine, caffeine, etc
Alkaloids
A naturally occurring opium-derived alkaloid
-Ex: morphine or codeine
Opiate
A more inclusive group, it refers to any natural, synthetic, or semi-synthetic compound with morphine like properties
Opioid
Most opioid analgesics in the clinic are
Mu-selective agonists
Located primarily in the brain where they function as neurotransmitters or neuromodulators
Endogenous Opioid peptides
Inhibits adenylyl cyclase-catalyzed formation of cAMP
Opioids such as morphine
Decreases the release of neurotransmitters that convey pain perception such as Ach, substance P, and glutamate
Morphine
Is an exception to the typical mu-opioids because it produces mydriasis instead of miosis
Meperidine
An analgesic used for acute pain from severe injuries, post-surgery, or bone/joint/muscle ailments
Morphine
For pulmonary edema, acts as an anxiolytics and vasodilator
Morphine
Oral analgesics for moderate, chronic pain
Oxycodone or hydrocodone
Used for relief of opioid-induced constipation
Methylnaltrexone
Hydrophilic drug, so CNS penetration and exit are slow. Slow onset and long duration
Morphine
Morphine is contraindicated in
Head injuries
We need to use caution with morphine use in patients with
Renal dysfunction
A more lipophilic prodrug of morphine that exhibits faster CNS penetration
Heroin (diamorphine)
Lipophilic drug, so very fast CNS penetration
-80-100 times more powerful than morphine
Fentanyl
Increase pain tolerance and decrease perception and reaction to pain
Opioids
Sometimes useful for pain caused by tissue/nerve inflammation (e.g. herpes zoster, shingles)
Opioids
More effective for prolonged, dull pain than sharp pain
Opioids
Opioids elicit euphoria by
Decreasing release of GABA and increasing release of dopamine
Opioids are generally contraindicated in cases of
Head injury
Tend to increase ICP and thus can exacerbate damage to the respiratory center in the brain
Opioids
opioids cause a decreased response to CO2 in the
Brainstem respiratory center
The resultant increase in arterial CO2 causes cerebral vasodilation and
Increased ICP
To treat this increased CO2, we give
Naloxone, NOT O2
Opioids also depress the cough centers in the
Medulla
Cause miosis by stimulating the E-W nucleus of the occulomotor nerve
Opioids (except Meperidine)
Opioid stimulation of the chemoreceptors trigger zone (CTZ) in the area postrema activates the
Vomiting center
The emetic effects of opioids are caused by stimulation of the vestibular apparatus. Thus, patients who are most likely to vomit are
Ambulatory patients
Large IV doses of fentanyl can cause
Muscle rigidity
Full agonist opioids can cause non-immunologic release of
-Induces vasodilation and hypotension
Histamine
Decreases peristalsis in the small and large bowels, which can lead to
Constipation or cramping
Can induce spasmodic effects on smooth muscle along the biliary tree
-Results in Sphincter of Oddi Dysfunction (SOD)
Opioids
Tolerance to analgesia, respiratory depression, and euphoria develops gradually over
2-3 weeks of daily dosing
We can occasionally see seizures do to the CNS effects of metabolites of
Meperidine
A major cause of hospital admissions for drug abuse
Methadone
Agonist of all opioid receptors that is prescribed to patients AFTER opioid detoxification to prevent relapse
Naltrexone
Pure competitive antagonist at all opioid receptors and is widely used for emergency opioid overdose/intoxication
Naloxone
Provides immediate relief from acute respiratory depression, but can induce severe withdrawal symptoms
Naloxone
Act as kappa agonists to produce analgesia and mu antagonists
Mixed agonist-antagonists
