IL. Histamine

Question 1

2 things histamine is metabolized to?

mech of excretion?

Answer 1

N-methyhistamine
imidazole acetic acid
`
urinary excretion

Question 2

wt is histamine synthesized from?

enzyme?

Answer 2

histidine

histidine decarboxylase

Question 3

wt type of receptor is H1?

H2?

Answer 3

1 - Gq

2 - Gs

Question 4

2 drugs causing release of histamine?

Answer 4

sucinylcholine

morphine

Question 5

wr is histamine stored in GI?

2 things stimulating release?

Answer 5

ECL cells

Ach and gastrin

Question 6

chief storage site of histamine?

3 immunologic stimulators of release?

Answer 6

IgE
PGs
Leukotrienes

Question 7

where is histamine stored in the blood?

Answer 7

basophils

Question 8

how do H1 and H2 receptors induce vasodilation?

Answer 8

H1 on endothelium release NO (immediate)

H2 on SM (slow and sustained)

Question 9

hw do H1 and H2 receptors affect the heart?

Answer 9

inc rate and force of contraciton
H1 vasodilate –> reflex
H2 direct on cardiac muscle

Question 10

action of histamine in lungs? wc receptor?

Answer 10

bronchoconstriciton

H1

Question 11

aciton of histamine in gut? wc receptor?

Answer 11

inc gastric acid secretion H2

Question 12

4 actions of histamine in neurons?

Answer 12

pruritus/itching
pain
increase wakefullness
inhibits appetite

Question 13

wt is responsible for hives related to histamine? wt receptor?

Answer 13

inc capillary permeabity

H1 receptor

Question 14

triple response to cutaneous histamine? cause?

Answer 14

red spot - vasodilaiton

flare – axon reflex and vasodilation

wheal – capillary permeability

Question 15

H1 antagonist effect on:
vasodilation
permeability
heart rate
bronchoconstriction
acid secretion
pruritus
flare

Answer 15

vasodilation - inhibits
permeability - inhibits
heart rate - partially blocks
bronchoconstriction -- little effect
acid secretion - no effect
pruritus - some relief
flare - supress axon reflex and dilation

Question 16

2 other actions of first H1 antagonists? most effective?

Answer 16

antimuscarinc effects

motion sickness

promethazine

Question 17

do first or second generation H1 antagonists have more AEs?

Answer 17

first

Question 18

4 AEs of first generation H1 antagonists?

Answer 18

CNS stimulaiton (at conventional doses)
CNS depression (at theurapeutic doses)
antimuscarinic (dry mouth)
GI

Question 19

wc second gen H2 antagonist has AEs?

Answer 19

cetirizine

Question 20

5 indications for H1 antagonists?

Answer 20

allergy
bronchial astham
anaphylaxis
motion sickness
sedation

Question 21

action of H2 antagonists?

Answer 21

dec gastric acid secretion

Question 22

wc H2 antagonist inhibits CYP450?

Answer 22

cimetidine

Question 23

2 indications for H2 antagonists?

Answer 23

ulcer

GERD

Question 24

wc H1 antagonists is metabolized by Cyp3A4?

Answer 24

loratadine

Question 25

where are anti-H1s metabolized?

H2?

Answer 25

liver

kidney

Question 26

2 things reducing anti-H1 activity?

Answer 26

alcohol and CNS depressents

Question 27

MOA of cromolyn and nedocromil?

Answer 27

inhibit degranulation of mast cells