Histamine

Question 1

Compounds formed by tissues and act on them are?

Answer 1

Autacoids

Question 2

What is histamine?

Answer 2

Chemical messenger generated by mast cells

Question 3

Response of histamine?

Answer 3

1. Allergic and inflammatory reactions (act on IgE)
2. Gastric acid secretion
3. Neurotransmitter.

Question 4

Synthesis of histamine?

Answer 4

Decarboxylation of histidine by enzyme histidine decarboxylase.

Question 5

If histamine is not stored in granules, it is inactivated by?

Answer 5

Amine oxidase

Question 6

Stimuli for histamine release?

Answer 6

Destruction of cell by any trauma
Allergies
Anaphylaxis

Question 7

MOA of H1 receptors

Answer 7

Smooth muscle contraction
Increasing capillaries permeability
Enhance cytokines release

Question 8

Pros of 1st generation H1 antihistamine?

Answer 8

More effective and inexpensive

Question 9

Cons of 1st generation H1 antihistamine?

Answer 9

Cross CNS and causes sedation.

Question 10

Why are 2nd generation drugs more preferred?

Answer 10

Cannot cross CNS, no sedation

Question 11

DOC for allergic rhinitis and utricia?

Answer 11

Oral antihistamines

Question 12

Treatment for allergic conjunctivitis?

Answer 12

Azelastine
Olopatadine
Ketotifen

Question 13

H1 antihistamine are contraindicated in which condition?

Answer 13

Bronchial asthma
Pts on Monoamine oxidase inhibitors (MAOI) therapy.
Pts undergoing treatment for Alzheimer disease

Question 14

DOC for acute anaphylactic shock?

Answer 14

Epinephrine

Question 15

Drugs for motion sickness?

Answer 15

1. Diphenhydramine
2. Diphenhydrinate (above drug + theophylline)
3. Cyclizine
4. Meclizine
5. Promethazine
6. Scopolamine

Question 16

DOC for vertigo associated with vestibular disorders?

Answer 16

Meclizine

Question 17

Drugs for insomnia?

Answer 17

1. Diphenhydramine

2. Doxylamine

Question 18

Second generation H1 antihistamine drugs?

Answer 18

1. Loratadine
2. Fexofrnadine
3. Desloratadine
4. Cetirizine

Question 19

H1 antihistamine act on which other receptors?

Answer 19

Cholinergic
Alpha adrenergic
Serotonin

Question 20

Drug acting on serotonin causing what?

Answer 20

Cyproheptadine causes increase in appetite.

Question 21

Adverse effects of H1 antihistamine?

Answer 21

1. Sedation (fatigue, dizziness, tremors)
2. Dryness of nasal passage and mouth (anticholinergic)
3. Urinary retention/blurred vision
4. Headache
5. Contact dermatitis

Question 22

Overdose of H1 antihistamine cause?

Answer 22

Hallucinations, excitement, ataxia, convulsions, coma.

Question 23

MOA of H2 antihistamine?

Answer 23

Inhibitors of gastric acid secretion.

Question 24

H2 antihistamine are used for?

Answer 24

Treatment of ulcers and heartburn

Question 25

H2 antihistamine drugs?

Answer 25

Cimetidine
Ranitidine
Famotidine
Nizatidine