Histamine and Serotonin Drugs Class/Mechanism

Question 1

How are H1 receptor antagonists metabolized and how fast?

Answer 1

rapidly metabolized via liver microsomes

Question 2

What are H1 receptor antagonists used for and what are their general side effects?

Answer 2

Use: allergic reactions, motion sickness, nausea and vomiting in pregnancy, sleep aids.

SE: sedation; anti-muscarinic action, poisoning (especially children) with convulsions, allergy, local anesthesia

Question 3

Diphenhydramine (Benadryl)
class
mech
SE

Answer 3

Ether/ethanolamine derivative
H1 receptor antagonist
SE: anti-muscarinic, sedation

Question 4

Tripelennamine
Class
Mech
Use

Answer 4

ethylenediamine derivative
H1 receptor antagonist
Use: OTC sleep aid

Question 5

Cyclizine
Class
Mech
Use

Answer 5

Piperazine derivative
H1 receptor antagonist
Use: Motion sickness

Question 6

Promethazine
class
mech
use
SE

Answer 6

phenothiazine derivative
H1 receptor antagonist
Use: Antiemetic
SE: Anti-muscarinic, sedation

Question 7

Chlorpheniramine
Class
mech
use
SE

Answer 7

Alkylamine
H1 receptor antagonist
Use: Component of cold meds
SE: less sedation

Question 8

Laratadine (claritin)
class
mech
use
SE

Answer 8

Piperidine derivative
2nd gen H1 receptor antagonist
Use: Allergic rhinitis
SE: no sedation, rare CV effects

Question 9

Fexofenadine (allegra)
Class
mech
use
SE

Answer 9

Piperidine derivative
2nd gen H1 receptor antagonist
Use: Allergic rhinitis
SE: no sedation, rare CV effects

Question 10

Azelastine
mech
use
SE

Answer 10

2nd gen H1 receptor antagonist
Use: allergic rhinitis (internasal spray), allergic conjunctivitis (opthalmic solution)
SE: No sedation

Question 11

Cetirizine
mech
use
SE

Answer 11

2nd gen H1 receptor antagonist
Use: allergic rhinitis
SE: No sedation

Question 12

Cimetidine
Mech
use
SE

Answer 12

H2 receptor antagonist; blocks gastric acid secretion (more so with nocturnal acid secretion than meal secretion)
Use: Dyspepsia, duodenal and gastric ulcers, hypersecretory conditions
SE: Antiandrogen (causing impotence and gynecomastia), inhibition of P450 enzymes

Question 13

Ranitidine (Zantac)
Mech
Use
SE

Answer 13

H2 receptor antagonist; blocks gastric acid secretion (more so with nocturnal acid secretion than meal secretion)
Use: Dyspepsia, duodenal and gastric ulcers, hypersecretory conditions
SE: Liver toxicity

Question 14

Famotidine
Mech
Use

Answer 14

H2 receptor antagonist; blocks gastric acid secretion (more so with nocturnal acid secretion than meal secretion)
Use: Dyspepsia, duodenal and gastric ulcers, hypersecretory conditions

Question 15

Nizatidine
Mech
Use

Answer 15

H2 receptor antagonist; blocks gastric acid secretion (more so with nocturnal acid secretion than meal secretion)
Use: Dyspepsia, duodenal and gastric ulcers, hypersecretory conditions

Question 16

Why do second gen H1 antagonists cause less sedation?

Answer 16

poorly cross BBB

Question 17

What is a possible SE of all H2 antagonists?

Answer 17

CNS dysfunction possible

Question 18

Cyproheptadine
mech
Use
SE

Answer 18

Antihistaminic and antiserotinergic
Use: Skin allergies (urticaria, anti-5HT1)
Diarrhea of carcinoid syndrome (anti 5HT2)

SE: Sedation, antimuscarinic

Question 19

Ketanserin
Mech
Use

Answer 19

Selective 5HT2A, 2C receptor antagonist as well as alpha 1 and H1 receptor antagonist

Use: Antihypertensive (Relaxes vascular and tracheal smooth muscle), antiplatelet aggregation

Question 20

Odansetron
Mech
Use

Answer 20

5HT3 receptor antagonist

Use: Nausea and vomiting in chemotherapy

Question 21

Ergot Alkaloids
Mech
SE

Answer 21

Agonist and antagonist actions at 5HT and alpha adrenergic receptors (also some dopamine)

SE: powerful hallucinations, smooth muscle contraction (vascular and uterine)

Question 22

Ergotamine
Class
Mech
Use
SE

Answer 22

Ergot alkaloid
nonspecific partial agonist at all 5HT1,2 receptors; partial agonist at alpha adrenergic receptors
Use: Prodrome of migraines
SE: N/V, cumulative and prolonged vasoconstriction

Question 23

Methysergide
Class
Mech
use
SE

Answer 23

Ergot alkaloid
partial agonist at all 5HT1 receptors, antagonist at 5HT2
Use: Prophylaxis of migraines
SE: GI disturbances, inflammatory fibrosis (chronic use), hallucinations

Question 24

Ergonovine
Class
Mech
Use

Answer 24

ergot alkaloid
alpha agonists
pospartum hemorrhage (Oxytocic)

Question 25

Bromocriptine
Class
Mech
Use

Answer 25

Ergot alkaloid
Dopamine agonist
Use: parkinsonism, hyperprolactinemia

Question 26

Triptans
Class
Mech
Use

Answer 26

Non-ergot serotonin analog
5HT1,b,D receptor agonist
Use: Effective (70%) migraine treatment.