module 2 antihistamines

Question 1

allergic reaction patho

Answer 1

Th cells recruit B cells to produce IgE Ab against allergen

• > degranulation of mast cells and basophils
• > release of histamine and other inflammatory mediators

Question 2

histamine inflammatory effects

Answer 2

erythema
edema
itching

Question 3

histamine synthesis

Answer 3

mast cells and basophils
gastric mucosal cells
some CNS neurons

Question 4

histamine activity

Answer 4

inflammatory mediator
regulates gastric acid secretion
regulates neurotransmission

Question 5

H1 receptor effects in lungs

Answer 5

bronchoconstriction -> asthma

Question 6

H1 receptor effects in vascular smooth muscle

Answer 6

postcapillary venule dilation

-> erythema

Question 7

H1 receptor effects in vascular endothelium

Answer 7

cellular contraction

-> edema

Question 8

H1 receptor effects in peripheral nerves

Answer 8

sensitization

-> itching, pain

Question 9

H2 receptor effects in heart

Answer 9

minor inc. in heart rate and contractility

Question 10

H2 receptor effects in stomach

Answer 10

inc. gastric acid secretion

- > PUD, GERD

Question 11

H1 antihistamines MOA

Answer 11

inverse agonist

• stabilized inactive H1 receptor
• inactivates active receptor

Question 12

H1 antihistamine metabolism

Answer 12

hepatically metabolized by CYP450

Question 13

H1 antihistamine 1st gen

Answer 13

lipophilic
neutral at physiologic pH
- diphenhydramine
- hydroxyzine
- chlorpheniramine
- promethazine
- doxepin

Question 14

H1 antihistamine 2nd gen

Answer 14

albumin binding 
ionized at physiologic pH
- loratidine
- Desloratidine
- cetirizine
- levocetirizine
- fexofenadine

Question 15

H1 antihistamine uses

Answer 15

rhinitis
conjunctivitis
urticaria
pruritis
Not effective for:
- anaphylaxis
- asthma

Question 16

H1 antihistamine and motion sickness, n/v r/t chemo drugs

Answer 16

diphenhydramine
dimenhydrinate
meclizine
promethazine

Question 17

H1 antihstamine insomnia drugs

Answer 17

diphenhydramine

doxylamine

Question 18

H1 antihistamine AE

Answer 18

CNS toxicity: sedation
Cardiac toxicity: QT prolongation
anticholinergic effects
- pupil dilation
- dry eyes
- dry mouth
- urine retention
- ileus