Serotonin Agonists & Antagonists

Question 1

The amino acid precursor of Serotonin is?

Answer 1

Tryptophan

Question 2

Site of Serotonin Synthesis in the CNS?

Answer 2

Raphe nuclei of the brain stem.

Question 3

List 3 drugs classified under 5HT1 Receptor agonists.

Answer 3

BET
* Buspirone
* Ergotamine - partial
* Triptans

Question 4

List 2 examples of drugs classified under 5HT1 Receptor Antagonists.

Answer 4

• Spiperone
• Methiothepin

Question 5

What is the major drug that functions as a 5HT2 receptor agonist?

Answer 5

Lysergic Acid Diethylamide ( LSD)

Question 6

State 5 major drugs under 5HT2 receptor antagonists.

Answer 6

• Pastor - Pizotifen
• Ken - Ketanserin
• Made - Methysergide
• Christians - Cyproheptadine
• Pray - Phenoxybenzamine
• Religiously - Ritanserin

Question 7

What is the mechanism by which 5HT3 receptors effects are mediated ?

Answer 7

Mediated through direct receptor coupled ion channels.

Question 8

State one major 5HT3 receptor agonist.

Answer 8

2- Methyl- 5HT

Question 9

List down 5 major 5HT3 receptor antagonist drugs.

Answer 9

DAGOT
D- Dolasetron
A- Alosetron
G- Granisetron
O- Ondansetron
T- Tropisetron

Question 10

Major drugs used as a 5HT4 receptor agonist?

Answer 10

• Metoclopramide
• Tegaserod - partial agonist

Question 11

State one major clinical application of Tegaserod.

Answer 11

Used in treatment of irritable bowel syndrome and constipation.
* NB- its use is restricted due to CVS toxicity.

Question 12

State the major drugs classified under 5HT4 receptor antagonists.

Answer 12

CRAM
* Cisapride
* Renzapride
* Alosetron ( but mainly 5HT3)
* Metoclopramide - but is mainly a D2 antagonist

Question 13

List 3 drugs commonly used in treatment of Carcinoid tumor.

Answer 13

• Ketanserin
• Cyproheptadine
• Phenoxybenzamine

Question 14

State one major clinical application of 5HT3 receptor antagonists.

Answer 14

• Antiemetic effects - use to prevent nausea and vomiting e.g post surgery or in patients undergoing cancer chemotherapy.
• Inhibit emetic action at the area postrema of the medulla .
  E g Ondansetron, Granisetron & Dolasetron.

Question 15

The most important receptor involved in cytotoxic drug induced vomiting is ?

Answer 15

Serotonin 5HT3 receptor.

Question 16

The most effective antiemetic drug for controlling cisplatin induced vomiting is?

Answer 16

Ondansetron

Question 17

Cisapride enhances gastrointestinal motility by ?

Answer 17

Activating serotonin 5HT4 receptors.

Question 18

State the major clinical manifestations associated with Serotonin Syndrome.

Answer 18

SHIVERS
S- Shivering
H- Hyperreflexia+ myoclonus
- Hypertension
- Hyper active bowel sounds
I- Increased temperature ( hyperthermia)
V- Vital Signs Instability
E- Encephalopathy
R- Restlessness
S- Sweating

Question 19

What are the therapeutic steps recommended in a patient with Serotonin Syndrome?

Answer 19

• Sedation using benzodiazepines.
• Intubation & ventilation if paralyzed .
• 5GT2 receptor blockers with Cyproheptadine & Chlorpromazine.

Question 20

Which drug causes cardiac arrhythmias when used by patients taking the gastrointestinal promotility agent Cisapride?

Answer 20

Ketoconazole

Question 21

GIT drug associated with the long QT syndrome and cardiac arrhythmias?

Answer 21

Cisapride

Question 22

Outline the major groups of drugs used in treatment of migraines.

Answer 22

• Triptans e.g sumatriptan .
• Ergot Alkaloids
• NSAIDS analgesic agents e.g ibuprofen.
• B- adrenoceptor blockers
• Calcium channel blockers e.g propranolol
• Tricyclic antidepressants
• SSRIS
• Anti seizure agents e.g Valrpoic acid & topiramate.