Opioid Analgesics and Antagonists Quiz

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary plant source for opioids?

  • Erythroxylum coca
  • Digitalis purpurea
  • Cannabis sativa
  • Papaver somniferum (correct)

Mu receptors produce the same effects as kappa receptors.

False (B)

Name the three types of opioid receptors.

Mu, Kappa, Delta

The opioid antagonist that has the highest affinity for mu receptors is called __________.

<p>Naloxone</p> Signup and view all the answers

Match the opioid types to their classification:

<p>Morphine = Strong agonist Codeine = Moderate agonist Buprenorphine = Mixed agonist-antagonist Naloxone = Antagonist</p> Signup and view all the answers

Which of the following is NOT a physiological effect produced by opioid activation?

<p>Increased blood pressure (C)</p> Signup and view all the answers

Endogenous peptides such as enkephalins interact with delta receptors.

<p>True (A)</p> Signup and view all the answers

What neurotransmitter is released due to the activation of peripheral nociceptive fibers by opioids?

<p>Substance P</p> Signup and view all the answers

Which of the following neurotransmitters is primarily inhibited by endogenous endorphins or exogenous opioid agonists?

<p>Substance P (A)</p> Signup and view all the answers

Kappa receptors mediate euphoria and have a high liability for dependence.

<p>False (B)</p> Signup and view all the answers

What is the major effect of opioids on the gastrointestinal system?

<p>Constipation</p> Signup and view all the answers

Opioid agonists may cause respiratory ______ as a significant adverse effect.

<p>depression</p> Signup and view all the answers

Match the following drugs with their properties:

<p>Morphine = Used in myocardial infarction Pethidine = Reduces shivering after anesthesia Buprenorphine = Partial agonist at mu receptor Naloxone = Opioid antagonist</p> Signup and view all the answers

Which of the following opioid related actions does not develop tolerance?

<p>Constipation (B)</p> Signup and view all the answers

Alvimopam is an opioid used to treat paralytic ileus.

<p>False (B)</p> Signup and view all the answers

Name one opioid that has anti-cholinergic activity and is relatively safer in biliary colic?

<p>Pethidine</p> Signup and view all the answers

Opioids can stimulate the CTZ and lead to ______ and vomiting.

<p>nausea</p> Signup and view all the answers

Match the following opioid antagonists with their specific uses:

<p>Naloxone = Used to reverse opioid overdose Naltrexone = Used in opioid addiction treatment Methylnaltrexone bromide = Used for opioid-induced constipation Alvimopan = Used for postoperative ileus</p> Signup and view all the answers

Flashcards

Opioids

These are substances derived from the poppy plant (Papaver somniferum) and are used for various effects like pain relief, sedation, and suppressing coughs.

µ (mu) receptor

The primary opioid receptor responsible for most of the effects associated with opioid use, including analgesia (pain relief), euphoria, and respiratory depression.

k (Kappa) receptor

The opioid receptor associated with dysphoria (unpleasant feelings), spinal analgesia, and constipation.

∂ (Delta) receptor

The opioid receptor associated with analgesia (pain relief), euphoria, and constipation.

Signup and view all the flashcards

Naloxone

The substance that blocks the effects of opioids, like morphine, by binding to opioid receptors.

Signup and view all the flashcards

Methadone

A strong opioid agonist that is often used for pain relief, specifically for chronic pain management due to its long-lasting effects.

Signup and view all the flashcards

Mixed agonist-antagonist opioid

A type of opioid that provides both agonist and antagonist effects, meaning that it can both activate and block opioid receptors.

Signup and view all the flashcards

Opioid Antagonists

A type of opioid that primarily blocks the effects of other opioids, producing no analgesic effects itself.

Signup and view all the flashcards

How do opioids work?

Opioids, like morphine, reduce pain by inhibiting the release of Substance P, a neurotransmitter that signals pain. This inhibition happens pre-synaptically, meaning it occurs before the pain signal reaches the brain.

Signup and view all the flashcards

Opioid Receptor Types

Morphine can act on µ, κ, and δ receptors. µ receptors are associated with the pleasurable feelings and addictive potential of opioids. κ receptors are linked to dysphoria or unpleasant feelings. δ receptors are also involved in pain relief but their specific role is less understood.

Signup and view all the flashcards

Opioid Tolerance

Tolerance develops to most of the effects of opioids, such as pain relief, sedation, and euphoria. However, tolerance does not develop to constipation, constricted pupils, or convulsions.

Signup and view all the flashcards

Opioid Sedation

Opioids cause sedation by affecting the brain regions responsible for alertness and wakefulness. However, some synthetic opioids like pethidine and fentanyl have less of a sedative effect than morphine.

Signup and view all the flashcards

Opioid Cough Suppression

Opioids suppress cough by acting on the cough center in the brain. This explains why opioid-containing cough syrups are used to reduce coughing.

Signup and view all the flashcards

Opioid Nausea and Vomiting

Opioids can cause nausea and vomiting by stimulating the chemoreceptor trigger zone (CTZ) in the medulla oblongata. This area is sensitive to certain drugs and toxins.

Signup and view all the flashcards

Opioid Effects on the Heart

Most opioids don't affect the heart directly. However, pethidine and pentazocine can increase heart rate.

Signup and view all the flashcards

Opioid Effects on Blood Pressure

Opioids can lower blood pressure by depressing the vasomotor system, which controls blood vessels. This can lead to a decrease in blood pressure.

Signup and view all the flashcards

Opioid Constipation

Opioids cause constipation by slowing down the movement of the intestines. This effect is due to opioid-induced relaxation of smooth muscle in the digestive system.

Signup and view all the flashcards

Clinical Uses of Opioids

Opioids are used to relieve pain, especially visceral pain, which is dull and constant, like that associated with internal organs. They are less effective for inflammatory pain.

Signup and view all the flashcards

Study Notes

Opioid Analgesics and Antagonists

  • Opioids: Derived from the poppy plant, Papaver somniferum, used for analgesia, euphoria, sedation, cough suppression, and diarrhea relief.

Opioid Receptors

  • Types: Mu (µ), Kappa (κ), and Delta (∂) receptors.
  • Mechanism: These are G protein-coupled receptors, inhibiting adenylate cyclase and influencing ion channels (increasing potassium efflux, reducing calcium influx).
  • Naturally occurring peptides: Endogenous opioid peptides (endorphins, dynorphins, and enkephalins) interact with these receptors, producing analgesic effects. β-endorphin preferentially interacts with µ receptors, enkephalins with ∂ receptors, and dynorphins with κ receptors.
  • Morphine and Naloxone: Morphine has higher affinity for µ receptors. Naloxone inhibits all opioid receptors, but has strongest action on µ receptors.

Effects of Different Opioid Receptors

  • µ receptors: Sedation, euphoria, respiratory depression, and physical dependence.
  • κ receptors: Dysphoria, spinal analgesia, constipation.
  • ∂ receptors: Analgesia, modulation of hormones and neurotransmitter release.

Classification of Opioids

  • Strong agonists: Morphine, methadone, meperidine
  • Moderate agonists: Codeine, oxycodone
  • Weak agonists: Propoxyphene
  • Mixed agonist-antagonists: Buprenorphine, nalbuphine, pentazocine
  • Antagonists: Naloxone, naltrexone, nalmefene, methylnaltrexone bromide, Alvimopan.

Opioid Agonists: Mechanism of Action

  • Pain signal inhibition: Opioid agonists act pre-synaptically to inhibit Substance P release, reducing neurotransmission via changes in ion conductances. This leads to hyperpolarization by increasing potassium conductance and inactivation of calcium channels.
  • Analgesia: This process halts neurotransmitter release and produces analgesic effects.

Opioid Agonists: Pharmacological Actions

  • Analgesia: Produces spinal and supraspinal analgesia through µ, κ, and ∂ receptors.
  • Other effects: Sedation, respiratory depression, cough suppression, nausea/vomiting (via CTZ stimulation), constipation, and decreased heart rate (except pethidine and pentazocine).
  • Peripheral effects: Intrabiliary pressure increase (contracting biliary smooth muscle), contraindicated in biliary colic, and potentially harmful to asthmatics (due to histamine release).

Opioid Agonists: Clinical Uses

  • Analgesia: Effective for visceral and dull pain, especially useful in myocardial infarction (Morphine IV) and neuropathic/cancer pain resistant to morphine (Methadone).
  • Shivering reduction: Pethidine is used after anesthesia.
  • Biliary colic: Pethidine is a relatively safer option compared to many opioid agents due to it's anticholinergic activity.

Opioid Agonists: Adverse Effects

  • General: Respiratory depression, nausea, vomiting, constipation, urinary retention, itching, dysphoria.
  • Tolerance: Develops to most effects, except miosis, constipation, and convulsions.
  • Dependence: Opioids have high potential for both psychological and physical dependence.
  • Withdrawal syndrome: Discontinuation can lead to withdrawal symptoms (rhinorrhoea, lacrimation, yawning, chills), which are opposite to the usual opioid effects.

Mixed Agonists-Antagonists

  • Buprenorphine: Partial µ agonist, κ and ∂ antagonist. Treatment for opioid withdrawal and analgesia.
  • Nalbuphine & Pentazocine: Kappa agonists, µ antagonists.

Opioid Antagonists

  • Naloxone, Naltrexone, Nalmefene: Used for opioid overdose reversal.
  • Methylnaltrexone bromide: Peripheral opioid antagonist, for paralytic ileus treatment.
  • Alvimopan: Peripheral opioid antagonist, for paralytic ileus.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser