Antihistamines

Question 1

What is the triple response of Lewis?

Answer 1

Red Spot- Cap Dilation
Flare- Axon reflex and BV dialtion
Wheal- Inc. Capillary Permaiability

Question 2

Where is histamine created and stored?

Answer 2

Mast cells

Question 3

What is the Tx for anaphylaxis?

Answer 3

Epinephrine

Question 4

What is Cytolytic Histamine Release? Caused by?

Answer 4

Membrane damage
High levels of drugs (phenothiazines, opioids and H1 receptor agonists)
Mechanical Damage

Question 5

What is Noncytolytic Histamine Release?

Answer 5

Immune Response that requires prior sensitization
Non-immuneological responsefrom basic polypeptides
Susbtances such as morphine, codeine, abtx, etc can displace Histamine from granules!

Question 6

What type of Ab receptor is on the surface of the Mast cell?

Answer 6

IgE receptor. FceRI

Question 7

What are the symptoms of an anaphylactic reaction?

Answer 7

Hypotension, vasodilation, myocardial depression, dysrhythmias, uticaria, angioedema, bronchospasm

Question 8

What is an anaphylactoid response?

Answer 8

Indistinguishable from anaphylaxis but not caused by an allergic response

Question 9

Where are H1 receptors expressed?

Answer 9

SM cells
Vascular endothelial cells
CNS Neurons
Peripheral sensory nerves

Question 10

Where are H2 receptors expressed?

Answer 10

Gastric Parietal Cells
Cardiac Muscle
CNS Neurons

Question 11

What G protein does H1 signal with?

Answer 11

Gq

PLC-IP3-Ca2+

Question 12

What g protein does H2 signal with

Answer 12

Gs
Inc Adenylyl cyclase
Inc Cyclic AMP-PKA

Question 13

Whaere are H3 receptors seen?

Answer 13

CNS Neurons

Peripheral sensory nerves

Question 14

Where are H4 receptors seen?

Answer 14

Inflammatory cells
Neutrophils
Eosinophils
Monocytes
Other immune Cells

Question 15

Where are Histaminergic neuron cell bodies seen?

Answer 15

The small area of the hypothalamus

Question 16

What is the end result of H1 and H2 receptor Activation

Answer 16

Vasodilation

Increase in vascular permiability

Question 17

What is the mechanism for itch?

Answer 17

H1 in peripheral neurons
Activation in epiderm causes itch
Activation in dermis causes pain

Question 18

What is the action of H1 activation in Smooth Muscle cells of the lung?

Answer 18

Elevation of airway fluid and electrolytes and bronchostriction

Question 19

What is the Action of H2 activation on cardiac muscle?

Answer 19

Increased Ca2+ => INC FORCE OF CONTRACTION

Speeds up SA node Depolarization which INC HR

Question 20

What is the action of Histamine in the immune response?

Answer 20

Accumulation of immune cells at the site of injury

Question 21

What are diseases that increaseHistamine levels?

Answer 21

Myelogenous Leukemia - Basophils– Chronic itching
Gastric Carcinoid tumors secrete histamine- -Vasodilation
Systemic mast cell diseases
-Mast cell leukemia

Question 22

What are the classes of antihistamines?

Answer 22

Physiological Antagonists
Release Inhibitors
Receptor antagonists

Question 23

What is the MOA of the Physiological Antagonists?

Answer 23

Reverse The phys effects of histamine.
-Sympathomimetic: Epinephrine
Relaxes bronchial SM

Question 24

What is the MOA of the Release inhibitors?

Answer 24

PRevents release of Histamine
Prophylactic Tx of Allergy
CROMOLYN, NEDOCROMIL
OMALIZUMAB
-monoclonal IgE Ab
Epinephrine

Question 25

What is the MOA of the Receptor Antagonists?

Answer 25

Compeditively Block receptors H1-allergy H2- Gastric acid secretion

Question 26

What are the common conditions treated by 1st gen Antihistamines?

Answer 26

Allergic Rhinitis Allervic Conjunctivitis Uticaria N/V Motion sickness sedatives Sleep Aids

Question 27

How is Emesis treated by antihistamines?

Answer 27

H1 receptors in the Vomiting center (tractus solitarus)

Question 28

What are the Sa of the 1st gen AHM?

Answer 28

Dec alertness, learning, memory Dry mouth, Urinary retention, Sinus tachy Inc appetitie, Weight gain Inc Dizziness, Inc Postural Hypotension Paradoxical exitation and seizures in kids

Question 29

What are the effects of Chlorpheniramine?

Answer 29

Mod sedationt Tx: Allergic Rhinitis and other allergic conditions No antiemetic action

Question 30

What are the effects of Diphenhydramine(benadryl?

Answer 30

Sig. Sedative Antimuscarinic Effects Allergic rhinitis, conjunctivitis, uticaria Local anesthetic effects Blk Na channels Acute Dystonic Rxns

Question 31

What is Pyrilamine used for?

Answer 31

Low sedation Little Antimuscarinic therefore No antimotion sickness

Question 32

What is Hydroxyzine used for?

Answer 32

Sedation and Antimusc Antiemetic, Sedative anxiolytic skin allergies

Question 33

What is Meclizine used for?

Answer 33

Minimal Antimuscarinic Actions | Less sedating than hydroxyzine

Question 34

What is Promethazine for?

Answer 34

Antiemetic, anti MS Local anesthetic Alpha Adr. receptor ant. Antimuscarinic

Question 35

Waht is the use of Cyproheptadine?

Answer 35

Sedative, antimuscarinic ANTI-SEROTONIN. Inc appetite/ wt gain Tx Serotonin Synd

Question 36

What are the drug interactions of H1 Antihistamines?

Answer 36

MAOI ADDITIVE SEDATIVE EFFECTS Dyphenhydaramine (benadril) overdose Leads to extreme sedation

Question 37

What is the metabolizer of Antihistamine? What can decrease their effects?

Answer 37

``` CYP2D6 and CYP3A4 ez in the liver Imidazole antifungals Cimetidine Macrolides H2 receptor antagonists ```

Question 38

What is different about the 2nd Gen H1 Antihistamines?

Answer 38

``` More selective for H1 Lower lipophilicity(less CNS) Non-compeditive inhibitor ```

Question 39

What are the applications of Azelastine?

Answer 39

Inhibits mast cell histamine release. Intranasal and opthalmic H1 receptor Antagonist

Question 40

What are the adverse effects of 2nd Gen H1 inhibitors?

Answer 40

Generally less sedative than 1st gen

Question 41

Which 2nd gen H1 receptors have a higher sedative effect?

Answer 41

Levocetirizine and Cetirizine

Question 42

If a patient had renal disorder which 2nd gen H1 receptor would you want to avoid?

Answer 42

Fexofenadine

Question 43

Drug interactions of fexofenadine?

Answer 43

Dont take with antacids or citrus juices

Question 44

What meds stabilize mast cells and decrease degranlation?

Answer 44

Cromolyn and Nedocromil

Question 45

What is the MOA of Omalizumab

Answer 45

Binds IgE and keeps it from activting MAst cells

Question 46

Which Tricycliclic antidepressant acts as antihistamine?

Answer 46

Doxepin and Ketotifen