Opioids and Drugs of Abuse Flashcards
(46 cards)
What is pain?
The perception of an unpleasant stimulus; the signal is transmitted from the periphery to the dorsal horn and the brain.
What are the primary pain neurotransmitters?
Substance P and glutamate (both are excitatory).
Which neurotransmitters are inhibitory in this context (reduce pain)?
GABA, serotonin, and norepinephrine.
What are the two components of pain?
Nociceptive and affective (the euphoria produced by pain medications addresses the affective component.
What are the three classifications of pain?
Nociceptive, neuropathic, and mixed – treatments vary for each kind.
What is nociceptive pain?
Pain which can be acute or chronic, mild to severe; therapy starts with NSAIDs and APAP before progressing to opioids.
What is neuropathic pain?
A burning, shock-like pain that is chronic and difficult to reverse; drugs target GABA, serotonin, and norepinehrine (opioids are not heavily implicated).
Which drugs can be used to treat both types of pain?
Tramadol and tapentadol.
Describe the pain pathway:
In response to a pain stimulus the brain releases three endgenous peptides (endorphins, enkephalins, and dynorphins), in both the CNS and periphery which activate Mu-opioid receptors.
What are Mu-receptors?
G-protein coupled receptors found in the brain, spinal cord, and periphery.
What occurs upon activation of the Mu-receptor?
Inhibition of adenylate cyclase; decreased cAMP; opening of potassium channels (hyperpolarization); and inhibition of calcium channels (decreased neurotransmitter release).
How does a pain stimulus lead to the activation of Mu-receptors?
The pain stimulus is generated in the periphery and passes to the primary afferent, where it causes the release of glutamate and substance P in the dorsal horn; these substances activate a secondary afferent, promoting the release of Mu-agonists.
What happens upon opioid (Mu) receptor activation?
Analgesia (Mu); euphoria (Mu); dysphoria (Kappa); respiratory depression (Mu/Kappa); CNS sedation and miosis (Mu/Kapa); N/V (Mu); constipation and difficulty urinating (periheral Mu); and histamine release and reduced immune function (peripheral Mu).
Tolerance will NOT build to which two effects of opioid receptor activation.
Miosis (pinpoint pupils) and constipation (patients on opioids must always take a laxative).
Describe the difference between the terms opiate, opioid, and narcotic:
Opiate: a substance derived from the poppy seed; Opioid: an opiate derivative; and Narcotic: an old term for a substance which induces sleep.
Describe how opioids are metabolized:
They undergo significant first-pass metabolism; the codeines (hydrocodone/oxycodone) undergo CY2D6, whereas the morphines (hydromorphone/oxymorphone) undergo phase II conjugation.
How do precautions differ between the codeines and the morphines?
Codeines have potential drug interactions; morphines should be avoided in the hepatically impaired; morphine should be avoided in the renally impaired.
Which drugs are considered phenanthrenes?
Codeine, mrphine, hydrocdone, oxycodone, oxymorphone, and buprenorphine.
What is buprenorphine?
A partial agonist which can be used alone for pain, or in combination with naloxone for treating abuse (Subxone).
What is codeine?
An antitussive and weak analgesic that is sometimes used for pain (Tylenol 3).
What is a metabolic concern when using morphine?
It has an active metabolite (M6G) that can cause renal failure in excess.
What are the two uses of hydrocodone?
It is combined with APAP to treat pain (Vicodin/Norco); or combined with homatropine for use as an antitussive (Hycodan).
What is the most potent phenanthrene?
Opana (oxymorphone); it has an active metabolite, and is often used for chronic pain in cancer patients.
Which drugs are phenylpiperidines?
Mepdridine, fentanyl, sufentanil,malfentanil, remifentanil.
