Opiod analgesics

Question 1

MOA of
Morphine
Codeine
Oxycodone

Answer 1

All three opioid receptors are G coupling protein
1. presynaptically inhibit Ca2+ channel
Result in inhibition of release of neurotransmitters: ACh, NE, 5-HT, glutamate and substance-P, GABA
2. post synaptically enhance K+ channel
3. inhibit adenylyl cyclase activity (cAMP decrease)

Question 2

MOA of Meperidine

Answer 2

All three opioid receptors are G coupling protein
1. presynaptically inhibit Ca2+ channel
Result in inhibition of release of neurotransmitters: ACh, NE, 5-HT, glutamate and substance-P, GABA
2. post synaptically enhance K+ channel
3. inhibit adenylyl cyclase activity (cAMP decrease)

Question 3

MOA of Methadone

Answer 3

All three opioid receptors are G coupling protein
1. presynaptically inhibit Ca2+ channel
Result in inhibition of release of neurotransmitters: ACh, NE, 5-HT, glutamate and substance-P, GABA
2. post synaptically enhance K+ channel
3. inhibit adenylyl cyclase activity (cAMP decrease)

Question 4

MOA of Buprenorphine

Answer 4

μ partial agonist, weak antagonist on κ & δ receptors

Long duration of action (high affinity binding to the receptor makes it difficult for its effects to be reversed by naloxone)

Question 5

MOA of
Nalbuphine
Pentazocine
Butorphanol

Answer 5

Agonistic effect on one type of opioid receptor and have antagonistic effect on others

Nalbuphine (kappa receptor agonists, µ receptor antagonist)

Pentazocine and butorphanol (kappa agonist, μ partial agonist or antagonist)

Question 6

MOA of Naloxone

Answer 6

Promptly reverses the symptoms of opioid toxicity
But duration only 1-2h, need to repeat dose
Ventilatory support given along with naloxone

Question 7

MOA of Naltrexone

Answer 7

Opiod antagonist

Question 8

MOA of Dextromethorphan

Answer 8

Opioid derivative, also NMDA antagonist

Question 9

MOA of Loperamide

Answer 9

Meperidine derivative

Question 10

Uses of
Morphine
Codeine
Oxycodone

Answer 10

Codeine: antitussive

Apomorphine/morphine: vomiting

Analgesia

Management of acute pulmonary edema: morphine IV reduces anxiety, calms the patient, reduces preload and afterload

Question 11

Uses of Meperidine

Answer 11

Only one anti-M that can treat biliary spasm

Question 12

Uses of Methadone

Answer 12

Maintenance programs for addicts

Permits slow tapering effect and also diminishes the intensity of abstinence syndrome

Question 13

Uses of Buprenorphine

Answer 13

Low efficacy at mu receptor with high affinity, and dissociate from receptor very slow

Used for maintenance programs for addicts

Question 14

Uses of Naloxone

Answer 14

I.V. naloxone is used for both diagnosis and treatment of opioid overdose

Question 15

Uses of Naltrexone

Answer 15

Reduces craving for ethanol, and treats post operational ileus (T1/2 10h)

Naltrexone/bupropion: weight loss

Methylnaltrexone treats opioid-induced constipation (do not cross BBB)

Question 16

Uses of Dextromethorphan

Answer 16

Cough suppression

Question 17

Uses of Loperamide

Answer 17

Antidiarrheal

Not absorbed from GI, low lipid soluble—very less abuse potential

Question 18

Which drugs cause chest muscle tone increase, chest rigidity → preanesthetic medication and intraoperative anesthesia

Answer 18

Fentanyl

Morphine

Question 19

ADR of

Morphine

Answer 19

Apomorphine/morphine: vomiting

Question 20

ADR of Meperidine

Answer 20

Pupillary dilation

Seizures

Must wait 2 weeks before using SSRI or MAOI → serotonin syndrome

Question 21

ADR of Methadone

Answer 21

Withdrawal symptoms are milder in severity and longer in duration when compared to morphine

Question 22

ADR of Buprenorphine

Answer 22

Precipitate abstinence symptoms

Question 23

ADR of
Pentazocine
Butorphanol
Nalbuphine

Answer 23

Precipitate abstinence symptoms

Question 24

ADR of Dextromethorphan

Answer 24

Not addictive, not euphoric, and causes less constipation.

Banned by FDA to use to kids less than 6 years old

Question 25

Which drug’s metabolites inhibit serotonin reuptake, can cause serotonin syndrome if used together with SSRI or MAOI

Answer 25

Dextromethorphan