Pharmacology 3: Therapeutic Approach To Allergic Disorders

Question 1

Definition: an overreaction of the immune system to a normally harmless substance called allergen.

Answer 1

Allergy.

Question 2

List symptoms of hay fever?

Answer 2

Allergic conjunctivitis, itchiness, and runny nose.

Question 3

What is the most important mediator in type 1 hypersensitivity?

Answer 3

Histamine.

Question 4

What are the aims of symptomatic treatment of allergies?

Answer 4

1- prevent mediator release.
2- use mediator antagonists.
3- block mediator effects at target organs.

Question 5

What is the most widely used agents for allergies?

Answer 5

1- anti-histamines.
2- leukotriene modifiers.
3- prostaglandin antagonists.

Question 6

How does histamine cause inflammation?

Answer 6

By increasing vasodilation, capillary permeability, causing smooth muscle concentration, mucus secretion, and parasympathetic nerve stimulation.

Question 7

Where is histamine present?

Answer 7

In mast cells, skin, GIT mucosa, lungs, liver and placenta.
Also present in blood, secretions, venoms and pathological fluids.

Question 8

Where are non-mast cell histamines present?

Answer 8

In brain, epidermis, gastric mucosa and growing regions.

Question 9

Antihistamines act on which histamine receptor?

Answer 9

H1.

Question 10

Where is H2 receptor present?

Answer 10

In the stomach.

Question 11

What are drugs that act on H2 receptor called?

Answer 11

H2 blockers.

Question 12

List H1 receptor agonists?

Answer 12

Betahistadine.

Question 13

List H1 receptor antagonists?

Answer 13

Mepyramine,
Chlorpheniramine,
Cetirizine.

Question 14

What is H1 receptor type?

Answer 14

Gq-coupled receptor.

Question 15

What is H1 effector pathway?

Answer 15

PIP2 hydrolysis - IP3/DAG intracellular Ca2+ release ptn. Kinase C-activation.

Question 16

List H1 receptor distribution?

Answer 16

• smooth muscles.
• blood vessels.
• afferent nerve endings-stimulation.
• ganglionic cell +.
• adrenal medulla - release of C.A’s.
• brain - neurotransmitter.

Question 17

List H2 receptor agonists?

Answer 17

4-methyl histamine,
Dimaprit,
Impromidine.

Question 18

List H2 receptor antagonists?

Answer 18

Cimetidine,
Ranitidine.

Question 19

What is H2 receptor type?

Answer 19

Gs-coupled receptor.

Question 20

What is H2 effector pathway?

Answer 20

Adenylyl cyclase activation - CAMP- phosphorylation of specific proteins.

Question 21

What is H2 receptor distribution?

Answer 21

• gastric glands.
• blood vessels.
• heart.
• uterus (rats).
• brain - neurotransmitter.

Question 22

List the pathophysiological role of histamine?

Answer 22

1- gastric acid secretions.
2- allergic phenomena - early type 1 hypersensitivity.
3- as transmitter.
4- inflammation.
5- tissue growth & repair.
6- asthma contraindications.

Question 23

What is the therapeutic value of histamine?

Answer 23

Histamine is of no therapeutic value.

Question 24

List 3 histamine uses?

Answer 24

1- testing gastric acid secretion; to test acid secreting ability of stomach.
2- diagnosis of pheochromocytoma; histamine releases CA and BP raises.
3- pulmonary function; to test for bronchial hyper activity.

^ all of these are no recommended anymore.

Question 25

List the pharmacological action of antihistamines?

Answer 25

1- antagonism of histamines; blocks histamine receptor NOT histamine release. 2- local anesthetic action; membrane stabilizing activity. 3- fall in BP - on IV injection.

Question 26

List the affect of antihistamines antagonism of histamines?

Answer 26

1- broncho constriction and smooth muscle constriction. 2- triple response. 3- fall in BP. 4- animal death (pre-treatment with H1 blockers). 5- adrenaline release. 6- vasoconstriction of large BV. 7- no action on gastric acid secretion.

Question 27

What is the anticholinergic action of antihistamines?

Answer 27

Dryness of mouth, blurred vision, urinary retention.

Question 28

Which antihistamines have high anticholinergic action?

Answer 28

1- promethazine. 2- diphenhydramine. 3- dimenhydrinate. 4- pheniramine. 5- cyproheptadine.

Question 29

Which antihistamines have low anticholinergic action?

Answer 29

1- chlorpheniramine. 2- hydroxyzine. 3- tripolidine. 4- cyclizine.

Question 30

Which antihistamines have minimal/absent anticholinergic action?

Answer 30

1- fexofenadine. 2- astemizole. 3- loratadine. 4- cetirizine. 5- mizolastin.

Question 31

Which generation of antihistamine are long acting?

Answer 31

2nd generation.

Question 32

Which generation of antihistamine are short-intermediate acting?

Answer 32

1st generation.

Question 33

Which generation of antihistamine are able to penetrate the CNS?

Answer 33

1st generation - more sedative, cannot be used by persons requiring constant attention like truck drivers.

Question 34

Which generation of antihistamine have anticholinergic activity?

Answer 34

1st gen.

Question 35

Which generation of antihistamine have no anticholinergic activity?

Answer 35

2nd gen.

Question 36

Which generation of antihistamine have antihistaminic action?

Answer 36

1st gen.

Question 37

Which generation of antihistamine have antiallergic action?

Answer 37

2nd gen.

Question 38

Which generation of antihistamine work on both central and peripheral HR?

Answer 38

1st gen.

Question 39

Which generation of antihistamine work only on peripheral HR?

Answer 39

2nd gen.

Question 40

Which generation of antihistamine impairs psychomotor performances?

Answer 40

1st gen.

Question 41

List the actions of 1st generation antihistamines?

Answer 41

Antipruritic, antiemetic and antitussive, anticholinergic and antiparkinonian.

Question 42

List the actions of 2nd generation antihistamines?

Answer 42

Only antihistamines and anti-allergic, urticaria, dermographisim, atopic eczema, food and drug allergy.

Question 43

Which generation of antihistamines has synergistic actions i.e., DI?

Answer 43

1st gen.

Question 44

List highly sedative antihistamines?

Answer 44

1- dimenhydrinate. 2- diphenhydramine. 3- doxylamine. 4- hydroxyzine. 5- promethazine.

Question 45

What is the duration of action of highly sedative antihistamines?

Answer 45

4–6 hours.

Question 46

List the uses of highly sedative antihistamines?

Answer 46

1- anti-motion sickness. 2- used as sleep aid. 3- anti emetic.

Question 47

List moderately sedative antihistamines?

Answer 47

1- pheniramine. 2- cyproheptadine. 3- meclizine. 4- buclizine. 5- cinnarizine.

Question 48

What is the duration of action of moderately sedative antihistamines?

Answer 48

4-6 hrs.

Question 49

List the uses of moderately sedative antihistamines?

Answer 49

1- anti serotonin effects. 2- anti motion sickness.

Question 50

List mildly sedative antihistamines?

Answer 50

1- cyclizine. 2- chlorpheniramine. 3- dimethindine. 4- tripolidine.

Question 51

What is the duration of action of mildly sedative antihistamines?

Answer 51

4-6 hrs.

Question 52

List 2nd generation antihistamines?

Answer 52

1- fexofenadine. 2- loratadine. 3- des loratadine. 4- astemizole. 5- cetirizine. 6- levo cetirizine. 7- azelastine. 8- ebastine.

Question 53

What is the duration of action of 2 gen antihistamines?

Answer 53

12-24 hrs.

Question 54

List the uses of 2nd gen antihistamines?

Answer 54

Sneezing, itching but do not significantly improve nasal congestion.

Question 55

Which drug is life saving in laryngeal angioedema and anaphylactic shock?

Answer 55

Adrenaline.

Question 56

Which drug is used for seasonal asthma?

Answer 56

Cetirizine.

Question 57

Antihistamine are ineffective in which conditions?

Answer 57

Asthma, humoral and cell mediated allergies.

Question 58

List the antipruritic actions of older antihistamines?

Answer 58

1- motion sickness. 2- morning sickness. 3- vertigo. 4- preanesthetic medication.

Question 59

Which older antihistamines are used in morning sickness?

Answer 59

1- promethazine. 2- dimenhydrinate. 3- cyclizine.

Question 60

Which antihistamines are used in vertigo?

Answer 60

H1, M1 and 5HT blocker, sedative, vasodilator and CA2+ influx - cinnarizine,

Question 61

Which antihistamine is used as a preanesthetic?

Answer 61

Promethazine.

Question 62

Which antihistamines are used as sedative, hypnotic and anxiolytic?

Answer 62

Promethazine and hydroxyzine.

Question 63

Which antihistamines are used as appetite stimulant?

Answer 63

Cyproheptadine.

Question 64

What is disodium cromoglyate?

Answer 64

Mast cell stabilizer.

Question 65

List histamine release inhibitors?

Answer 65

1- nedocromil. 2- lodoxasmide. 3- permirolast. 4- ketotifen.

Question 66

How do histamine release inhibitors act?

Answer 66

They act by preventing mast cell degranulation due to immunological reaction. Prevent the release of H and other inflammatory mediators.

Question 67

What is ketotifen used for?

Answer 67

It has mast cell stabilizing property, good for patients with multiple allergic manifestations.

Question 68

What are histamine release inhibitors used in?

Answer 68

Bronchial asthma and allergic rhinitis.

Question 69

List the therapeutic aspects of immunotherapy (desensitization)?

Answer 69

1- slowly increasing doses of allergen. 2- administration is usually SC, although nasal, bronchial, sublingual and oral routes are possible. 3- patients should be observed at least 20 min after injection for avoidance of side effects. 4- must be used for at least 2 years in order to maintain benefit.

Question 70

List the indications of immunotherapy (desensitization)?

Answer 70

1- allergic rhinitis and allergic asthma: pollen, house dust, mite, cat and dog, immunotherapy is beneficial. 2- Hymenoptera sensitivity: efficacy of immunotherapy in case of insect venom has been established. No evidence to support the use of food immunotherapy.

Question 71

List the first line treatment of allergies?

Answer 71

1- adrenaline: at first sign of anaphylaxis, given IM. 2- tourniquet. 3- oxygen. 4- anti-histaminics IV. 5- corticosteroids IV.

Question 72

List second line of treatment of allergies?

Answer 72

1- IV fluids. 2- IV aminophylline. 3- intubation and tracheostomy. 4- maintain supportive therapy.