Opioids with Weak and Partial Agonist Activity and Opioid Antagonists Flashcards
Why are dihydrocodeine and codeine oral doses similar despite differences in bioavailability?
A. Dihydrocodeine is more potent than codeine
B. Dihydrocodeine is more efficacious than codeine
C. Dihydrocodeine is a full agonist
D. Dihydrocodeine is a weaker opioid
E. Dihydrocodeine has higher bioavailability than codeine
A. Dihydrocodeine is more potent than codeine.
B. Incorrect. Dihydrocodeine and codeine have similar efficacies at opioid receptors.
C. Incorrect. Like codeine, dihydrocodeine is a weak opioid agonist compared to morphine, which is a full agonist.
D. Incorrect. Dihydrocodeine is a stronger opioid than codeine because it is more potent.
E. Incorrect. Dihydrocodeine has a lower bioavailability than codeine, which is why they have similar doses, despite dihydrocodeine being more potent.
Which of the following is correct regarding codeine:
A. It is metabolised predominantly to morphine
B. Codeine is an opioid agonist
C. Weak opioids are as potent as morphine
D. Codeine has a lower oral bioavailability than morphine
E. Codeine is a synthetic opioid
B. Codeine is an opioid agonist. Codeine itself has very weak action on mu receptors but it does display some agonism. However, to really have an analgesic effect it needs to be converted to morphine.
A. Incorrect. 70-80% is metabolised to codeine-6 glucuronide, with only 5-10% being metabolised to morphine.
C. Incorrect. Weak opioids are less potent than morphine which is a full agonist.
D. Incorrect. Oral bioavailability of codeine is about 50% compared to only 20-30% for morphine.
E. Incorrect. Codeine is a natural opioid derived from opium.
Which of the following is correct regarding buprenorphine:
A. Is a synthetic derivative of thebaine
B. Can be delivered transdermally
C. Should be continued perioperatively
D. Dissociates quickly from MOR receptors
E. Is a KOR receptor agonist
B. It can be delivered transdermally as well as sublingually, bucally and IV.
A. Incorrect. Buprenorphine is a semi-synthetic analogue of thebaine.
C. Incorrect. Buprenorphine is a partial agonist at the MOR receptor. You should consider stopping it perioperatively as it may prevent opioid agonists from working effectively for acute pain.
D. Incorrect. Buprenorphine binds to MOR receptors with high affinity.
E. Incorrect. It is a KOR receptor antagonist.
Which of the following is correct regarding naloxone:
A. Causes pulmonary oedema
B. Is not an antagonist at MOR receptors
C. Can cause hypotension
D. Is not an antagonist of agonist-antagonist drugs
E. May cause an increase in sympathetic tone
E. May cause an increase in sympathetic tone
A. Incorrect. Naloxone can cause sweating, nausea, restlessness, trembling, vomiting, flushing and headache in people with opioids on board, but has only very rarely been associated with seizures and pulmonary oedema.
B. Incorrect. Naloxone is an antagonist at MOR receptors.
C. Incorrect. Naloxone tends to increase sympathetic tone and cause hypertension.
D. Incorrect. Naloxone will still antagonise the MOR receptor in the presence of agonist-antagonist drugs.
Which of the following is correct regarding naltrexone?
A. Is used for the treatment of opioid overdose
B. Should be omitted prior to surgery
C. Has a duration of 4 hours
D. Is only effective for the treatment of opioid addiction
E. Is a partial MOR antagonist
B. It should be omitted prior to surgery as it will block the opioid receptors, rendering opioids used for management of acute pain ineffective.
A. Incorrect. Naltrexone is used for opioid and alcohol dependence.
C. Incorrect. The half life of naltrexone is 13 hours.
D. Incorrect. It is effective for both opioid addiction and alcohol dependence.
E. Incorrect. It is a competitive MOR antagonist.
Which of the following is correct regarding codeine?
A. The metabolites of codeine are not MOR agonists
B. Codeine is more potent than dihydrocodeine
C. Codeine has a higher oral bioavailability than dihydrocodeine
D. Codeine has a lower bioavailability than morphine
E. Codeine is a partial agonist of the MOR receptor
C. Codeine has a higher oral bioavailability than dihydrocodeine. Dihydrocodeine bioavailability is only 20%.
A. Incorrect. Codeine has active metabolites which can act at the MOR receptor.
B. Incorrect. Codeine is less potent that dihydrocodeine but has a higher oral bioavailability, which is why the doses appear similar.
D. Incorrect. Codeine has higher bioavailability than morphine because it undergoes less first-pass metabolism.
E. Incorrect. Codeine is a full agonist at MOR receptors.
A dose of 10 mg of morphine is given to a patient. Which one of the following is correct?
A. There would be no difference in effect in a patient taking naltrexone for alcohol dependence
B. A patient taking buprenorphine would experience reduced efficacy of the morphine
C. A patient taking codeine regularly would not have an increased risk of side effects
D. A dose of naloxone would reverse the effect immediately and last for 13 hours
E. Renal function has no effect on morphine effects
B. A patient taking buprenorphine would experience reduced efficacy of the morphine. As buprenorphine is a partial agonist with high receptor affinity, in the presence of morphine it will act as an antagonist.
A. Incorrect. Patients taking naltrexone will have a reduced effect from the morphine dose as this is an antagonist at MOR receptors.
C. Incorrect. There is an increased risk of side-effects with concomitant use of codeine, as both drugs act on the same receptor site.
D. Incorrect. Naloxone is able to reverse the effects of morphine rapidly, but the effect is not sustained.
E. Incorrect. Renal impairment can effect morphine excretion, leading to a build up in the patient’s system.
Which of the following is correct regarding naloxone?
A. The duration of action of most opioids is less than that of naloxone
B. It commonly causes pulmonary oedema
C. It is only supplied as a single medication for use in emergency opioid overdose
D. It can be administered repeatedly up to a maximum of 10 mg
E. It should not be used as an infusion
D. It can be administered repeatedly up to a maximum of 10 mg
A. Incorrect. Naloxone has a short half-life, and thus multiple doses may be required to combat opioid overdose, including as an infusion.
B. Incorrect. Naloxone can cause pulmonary oedema but this is not common.
C. Incorrect.
E. Incorrect. See A.
Which of the following is correct regarding the principles of agonism, antagonism, and different routes of administration of opioids?
A. Patients with fentanyl patches for chronic pain are likely to need lower opioid doses to control acute pain
B. High molecular weight drugs are more amenable to transdermal delivery than low molecular weight drugs
C. Fentanyl and buprenorphine patches can be used for chronic pain and cancer pain
D. Morphine can be delivered by transdermal patches
E. Only molecule size affects transdermal drug delivery
C. Fentanyl and buprenorphine patches can be used for chronic pain and cancer pain
A. Incorrect. Patients with chronic pain who are already on opioids are likely to have tolerance to opioids, and therefore will need higher opioid doses to control acute pain.
B. Incorrect. Low molecular weight drugs are able to cross the cell membranes for absorption.
D. Incorrect.
E. Incorrect. Transdermal drug delivery is affected by molecule size, polarity, temperature, barrier thickness, not just size of molecules.
