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NURS 123 Opioid Notes

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jasmine's version from 2016-01-03 06:50

Section 1

Question Answer
Analgesics Drugs that relieve pain without causing loss of consciousness
Opioid Any drug, natural or synthetic, that has actions similar to those of morphine
Opiate More specific and applies only to compounds present in opium (i.e., morphine, codeine)
Narcotic Used to mean an analgesic, a central nervous system (CNS) depressant, and any drug capable of causing physical dependence; Is also used in a legal context to designate not only the opioids yet also such diverse drugs as cocaine, marijuana, and lysergic acid diethylamide (LSD)
The term Opioid is preferable to... Narcotic as a label for a discrete family of pharmacologic agents
Nociception called also pain sense; The ability to feel pain, caused by stimulation of a nociceptor; Physiologically, it is composed of four processes: Transduction, transmission, modulation, and perception
Endogenous Opioid Peptides Found in the CNS and in peripheral tissues, and serve as neurotransmitters, neurohormones, and neuromodulators; however, their precise physiologic role is not fully understood
3 families of endogenous opioid peptides Enkephalins (either of two compounds, leu-enkephalin and met-enkephalin, that occur naturally in the brain; body’s natural painkillers; they are internally derived and bind to the body’s opioid receptors), endorphins (any of a group of hormones secreted within the brain and nervous system and having a number of physiological functions; they are peptides that activate the body’s opiate receptors, causing an analgesic effect), and dynorphins (An opiate-like chemical found in the brain, which blocks transmission of pain signals along nerve fibers, creating potent analgesic effects. It is also found throughout the central and peripheral nervous systems; most are agonists at opioid receptor sites, however some are involved in pain regulation and others in the hypothalamic regulation of eating and drinking) Another definition of dynorphins pertains to a class of opioid peptides that arise from the precursor protein prodynorphin. When prodynorphin is cleaved during processing by proprotein convertase 2 (PC2), multiple active peptides are released: dynorphin A, dynorphin B, and α/β-neo-endorphin
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Section 2

Question Answer
3 Main classes of opioid receptors Mu, kappa, and delta
Mu receptors are the most important due to... Opioid analgesics act primarily by activating mu receptors
How do Opioid analgesics act on Kappa receptors? By producing a weak activation of the receptors
Do Opioid analgesics interact with Delta receptors No
Do Endogenous opioid peptides act through all of the 3 main classes of opioid receptors? Yes
Important responses of the Mu receptor upon activation Analgesia, respiratory depression, sedation, euphoria, physical dependence, and decreased GI motility
Important responses of the Kappa receptor upon activation Analgesia, sedation, and decreased GI motility
Drugs that act at opioid receptors are classified on the basis of how They affect receptor function, and at each receptor, a drug can act in one of three ways: as an agonist, parrtial agonist, or antagonist
Partial Agonist A drug that produces low to moderate receptor activation when administered alone, yet will block the actions of a full agonist if the two are given together
3 major groups drugs that bind opioid receptors fall into Pure opioid agonists, agonist-antagonist opioids, and pure opioid antagonists
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Section 3

Question Answer
Pure opioid agonists (morphine, codeine, meperidine, and other morphine-like drugs) drug actions at Mu receptors Agonist
Pure opioid agonists (morphine, codeine, meperidine, and other morphine-like drugs) drug actions at Kappa receptors Agonist
Agonist-antagonist opioids (pentazocine, nalbuphine, butorphanol, and buprenorphine) drug actions at Mu receptors Antagonist
Agonist-antagonist opioids (pentazocine, nalbuphine, butorphanol) drug actions at Kappa receptors Agonist
Agonist-antagonist opioids (buprenorphine) drug actions at Mu receptors Partial agonist
Agonist-antagonist opioids (buprenorphine) drug actions at Kappa receptors Antagonist
Pure opioid antagonists (naloxone, naltrexone, others) drug actions at Mu receptors Antagonist
Pure opioid antagonists (naloxone, naltrexone, others) drug actions at Kappa receptors Antagonist
Psychotomimetic Relating to or denoting drugs that are capable of producing an effect on the mind similar to a psychotic state; Also known as psychotogenic; A drug with this action mimics the symptoms of psychosis, including delusions and/or delirium, as opposed to just hallucinations;
Mixed Mu receptor antagonist Kappa receptor agonist can cause dose-related what? Psychotomimesis
Kappa receptor activation may underlie what?Psychotomimetic effects seen with certain opioids
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Section 4

Question Answer
Pure opioid agonists Activate Mu and Kappa receptors, and can produce analgesia, euphoria, sedation, respiratory depression, physical dependence, constipation, and other effects
2 Groups of pure opioid agonists Strong opioid agonists and moderate to strong opioid agonists. Morphine is the prototype of the strong agonists, and Codeine is the prototype of the moderate to strong agonists.
Agonist-Antagonist opioids When administered alone, theses opioids produce analgesia; however, if given to a patient who is taking a pure opioid agonist, these drugs can antagonize analgesia caused by the pure agonist. Pentazocine (Talwin) is the prototype of the agonist-antagonists
4 agonist-antagonist opioids available Pentazocine (Talwin, Fortral, Sosegon, and others), Nalbuphine (Nubain, Manfine, and others), Butorphanol (only available in its generic formulations, as Stadol was discontinued by its manufacturer), and Buprenorphine (Buprenex, Subutex, Suboxone, Butrans, Cizdol, Zubsolv)
Ceiling Effect The phenomenon in which a drug reaches a maximum effect, so that increasing the drug dosage does not increase its effectiveness; Sometimes drugs cannot be compared across a wide range of treatment situations due to one drug may have a ceiling effect
Pentazocine (Talwin, Talwin PX [without nalozone], Talwin NX [with the μ-antagonist naloxone, will cause withdrawal in opioid dependent persons on injection], Fortral, Fortwin [lactate injectable form], Sosegon, Talacen [with acetaminophen], and others) Used primarily to treat pain, in the EOC colon although its analgesic effects are subject to a ceiling effect; Side effects are similar to those of morphine, but pentazocine, due to its action at the kappa opioid receptor is more likely to invoke psychotomimetic effects. High dose may cause high blood pressure or high heart rate. It may also increase cardiac work after myocardial infarction when given intravenously and hence this use should be avoided where possible
Administration routes of Pentazocine (Talwin, Talwin PX [without nalozone], Talwin NX [with the μ-antagonist naloxone, will cause withdrawal in opioid dependent persons on injection], Fortral, Fortwin [lactate injectable form], Sosegon, Talacen [with acetaminophen], and others) Oral, intravenous, and intramuscular
Nalbuphine (Nubain, Manfine, and others) Used for the relief of moderate to severe pain, and can also be used as a supplement to balance anesthesia, for pre-operative and post-operative analgesia, and for obstetrical analgesia during labor and delivery
Administration routes of Nalbuphine (Nubain, Manfine, and others) Intravenous, intramuscular, and subcutaneous
Butorphanol (only available in its generic formulations) Its most common indication is management of migraine using the intranasal spray formulation. Used parenterally for management of moderate-to-severe pain, as a supplement for balanced general anesthesia, and management of pain during labor. It is also quite effective at reducing post-operative shivering (owing to its Kappa agonist activity). It is more effective in reducing pain in women than in men.
Administration routes of Butorphanol (only available in its generic formulations) Intravenous, intranasal, and oral; however, tablet form is only used in dogs and cats due to low bioavailability in humans
Buprenorphine (Buprenex [solutions for injections that are often used for acute pain in primary-care settings], Subutex, Suboxone, Bunavail [used for opioid addiction], Butrans [transdermal preparations used for chronic pain], Cizdol, Zubsolv, Temgesic [sublingual tablets for moderate to severe pain], Norspan [transdermal preparations used for chronic pain], and others) Used to treat opioid addiction, such as heroin and oxycodone, in higher dosages, to control moderate acute pain in non-opioid-tolerant individuals in lower dosages and to control moderate chronic pain in even smaller doses
Administration routes of Buprenorphine (Buprenex, Subutex, Suboxone, Butrans, Cizdol, Zubsolv, and others) Sublingual, intramuscular, intravenous, transdermal, intranasal, rectally, and orally
Pure opioid antagonists Act as antagonist at Mu and Kappa receptors. These drugs Do Not produce analgesia or any of the other effects caused by opioid agonists.
Principle use of pure opioid antagonists Reversal of respiratory and CNS depression caused by overdose with opioid agonists. Naloxone (Narcon) is the prototype of the pure opioid antagonists
Methylnaltrexone (Relistor) Pure opioid antagonist used to treat opioid-induced constipation without affecting analgesia or precipitating withdrawals. Is a quaternary ammonium cation, so cannot cross the blood-brain barrier-so has antagonist effects throughout the body, counteracting effects such as itching and constipation
Warning about Methylnaltrexone (Relistor) Since a significant fraction (up to 60%) of opioid analgesia can be mediated by opioid receptors on peripheral sensory neurons, particularly in inflammatory conditions such as arthritis, traumatic or surgical pain, it may increase pain under such circumstances
Administration routes of Methylnaltrexone (Relistor) Oral, intravenous, and subcutaneous
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