Opioids

Question 1

NAME 3 Opioids and rank them in order of strength.

Answer 1

Morphine (~10% of opium) > Codeine (~0.5% of opium) > Thebaine (~0.2% of opium)

Morphine is a strong opioid agonist, Codeine is a weak opioid agonist, and Thebaine is a precursor for synthesis of naloxene, buprenoprhine and other opioid drugs

Question 2

What are the 3 types of opioid receptors?

Answer 2

mu receptor (MOR), kappa receptor (KOR), delta receptor (DOR). They are all G-protein coupled receptors (GPCR).

Question 3

NAME 2 actions of Opioids?

Answer 3

• Inhibition of the propagation of pain signals
• Alter the emotional perception of pain
• Elevate the pain threshold

Question 4

What are the sites of action of opioids?

Answer 4

• Peripheral nociceptive terminals (peripheral analgesia)
• The spine (spinal analgesia)
• The brain (supraspinal analgesia)

Question 5

LIST 5 side effects of Opioids. (Ranking them on dose-based side effect)

Answer 5

(Least severe)
1. Peripheral Analgesia
2. Spinal Analgesia
3. Cough suppression
4. Supraspinal Analgesia
5. Sedation
6. Reduced Gut motility
7. Euphoria
8. Pupil constriction
9. Constipation
10. Dysphoria
11. Severe sedation
12. Respiratory depression
(most severe)

Question 6

What are 3 dose-related CONSIDERATIONS when prescribing Opioids? (i.e. factors that would cause you to lower the dose)

Answer 6

1. Elderly patients usually require a lower dose to achieve effective pain relief than younger patients
2. Neuropathic pain requires higher opioid dose/ a stronger opioid than nociceptive pain
3. Lower doses are required for continuous maintenance of pain releif than administration in response to recurrence of pain

Question 7

Do you start Opioids high and titrate down, or start Opioids low and titrate up?

Answer 7

Start low and titrate up.

Opioids should be started at a low dose and carefully titrated until an adequate level of analgesia is obtained OR until persistent and unacceptable side effects warrant a re-evaluation of therapy.

Note: For some patients with chronic pain, opioids do not exert an appreciable analgesic effect until a threshold dose has been achieved

Question 8

NAME 2 Opioids that are commonly prescribed as analgesics

Answer 8

Codeine, morphine, pathidine

Question 9

What opioid is an anaesthetic adjuvant?

Answer 9

Fentanyl

Question 10

What opioid is used as a cough suppresant/ antitussive?

Answer 10

Codeine (cough syrup)

Question 11

Which opioid is prescribed as an anti-diarrohoeal?

Answer 11

Diphenoxylate

Question 12

What type of pain is Morphine and Fentanyl normally prescribed for?

Answer 12

Neuropathic pain (I.e. Cancer pain)

Question 13

Which has a longer half-life, Methadone or Fentanyl?

Answer 13

Methadone.

Methadone has a plasma half-life of >24 hours.
Fentanyl is a short acting anaesthetic adjuvant.

Question 14

Which Opioid is used to treat pain during childbirth?

Answer 14

Pethidine (Meperidine).

Pethidine has a shorter duration of action than morphine.

Question 15

What are some side effects of Pethidine?

Answer 15

Pethidine is a parasympatholytic anti-muscarinic agent.
It causes dry mouth (xerostomia), blurring of vision

Question 16

Codeine is converted to another Opioid by biological enzymes. Which opioid is this?

Answer 16

Morphine.
10% of Codeine is converted to morphine/ dihydromorphine.

Question 17

Name 2 other actions of Tramadol, besides sedation.

Answer 17

• Inihibition of Serotonin (5-Hydroxytryptophan) reuptake
• Inhibition of noradrenaline reuptake

Question 18

How do Opioids cause respiratory depression?

Answer 18

They act on the nucleus tractus solitarius and the nucleus ambiguus to
- Reduce responses to Co2 and H+
- Suppress voluntary breathing

Question 19

What are the 3 risk factors against prrescribing Opioids?

Answer 19

1. History of Fall/ Fall Risk
   - Opioids cause drowsiness, which can increase the chance of a fall
2. Constipation
   - Opioids reduce GIT motility, that can worsen the patient’s constipation (especially Codeine at high dose)
3. Urinary Retention/ History of BPH
   -Opioids cause urinary retention

Question 20

NAME 3 factors that increase the patient’s risk of suffering from Opioid-induced respiratory depression.

Answer 20

1. High dose
2. Existing respiratory disease
3. Hepatic Dysfunction
4. Combination with other CNS depressants
5. Young children (OPIOIDS SHOULD NOT BE PRESCRIBED TO INFANTS OR NEONATES)

Question 21

NAME 5 symptoms of Opioid withdrawal syndrome.

Answer 21

1. Anxiety
2. Irritability
3. Chills
4. Hot flushes
5. Joint pain
6. Lacrimation
7. Rhinorrhoea (runny nose)
8. Nausea
9. Vomiting
10. Abdominal cramps
11. Diarrhoea

Question 22

Describe Opioid Tolerance.

Answer 22

Opioid Tolerance is when opioids become less effective after prolonged use. This is such that the previous dose prescribed to control the patient’s pain can no longer control the patient’s pain. As such, dose escalation is required.

Question 23

Name 3 Opioid Antagonists.

Answer 23

Naloxene, Naltrexone, Nalmefene

Question 24

Which is longer-acting, Naloxone or Naltrexone?

Answer 24

Naltrexone.
Naloxone is a short-acting opioid antagonist, Naltrexone is a long acting opioid antagonist.
Naloxone is administered orally, Naltrexone is administered IV.