Antihistamines Flashcards Preview

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Flashcards in Antihistamines Deck (46)
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1
Q

What is the triple response of Lewis?

A

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

2
Q

Where is histamine created and stored?

A

Mast cells

3
Q

What is the Tx for anaphylaxis?

A

Epinephrine

4
Q

What is Cytolytic Histamine Release? Caused by?

A

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

5
Q

What is Noncytolytic Histamine Release?

A

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

6
Q

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

A

IgE receptor. FceRI

7
Q

What are the symptoms of an anaphylactic reaction?

A

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

8
Q

What is an anaphylactoid response?

A

Indistinguishable from anaphylaxis but not caused by an allergic response

9
Q

Where are H1 receptors expressed?

A

SM cells
Vascular endothelial cells
CNS Neurons
Peripheral sensory nerves

10
Q

Where are H2 receptors expressed?

A

Gastric Parietal Cells
Cardiac Muscle
CNS Neurons

11
Q

What G protein does H1 signal with?

A

Gq

PLC-IP3-Ca2+

12
Q

What g protein does H2 signal with

A

Gs
Inc Adenylyl cyclase
Inc Cyclic AMP-PKA

13
Q

Whaere are H3 receptors seen?

A

CNS Neurons

Peripheral sensory nerves

14
Q

Where are H4 receptors seen?

A
Inflammatory cells
Neutrophils
Eosinophils
Monocytes
Other immune Cells
15
Q

Where are Histaminergic neuron cell bodies seen?

A

The small area of the hypothalamus

16
Q

What is the end result of H1 and H2 receptor Activation

A

Vasodilation

Increase in vascular permiability

17
Q

What is the mechanism for itch?

A

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

18
Q

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

A

Elevation of airway fluid and electrolytes and bronchostriction

19
Q

What is the Action of H2 activation on cardiac muscle?

A

Increased Ca2+ => INC FORCE OF CONTRACTION

Speeds up SA node Depolarization which INC HR

20
Q

What is the action of Histamine in the immune response?

A

Accumulation of immune cells at the site of injury

21
Q

What are diseases that increaseHistamine levels?

A

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

22
Q

What are the classes of antihistamines?

A

Physiological Antagonists
Release Inhibitors
Receptor antagonists

23
Q

What is the MOA of the Physiological Antagonists?

A

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

24
Q

What is the MOA of the Release inhibitors?

A
PRevents release of Histamine
Prophylactic Tx of Allergy
CROMOLYN, NEDOCROMIL
OMALIZUMAB
-monoclonal IgE Ab
Epinephrine
25
Q

What is the MOA of the Receptor Antagonists?

A

Compeditively Block receptors
H1-allergy
H2- Gastric acid secretion

26
Q

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

A

Allergic Rhinitis
Allervic Conjunctivitis
Uticaria

N/V
Motion sickness
sedatives
Sleep Aids

27
Q

How is Emesis treated by antihistamines?

A

H1 receptors in the Vomiting center (tractus solitarus)

28
Q

What are the Sa of the 1st gen AHM?

A

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

29
Q

What are the effects of Chlorpheniramine?

A

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

30
Q

What are the effects of Diphenhydramine(benadryl?

A

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

31
Q

What is Pyrilamine used for?

A

Low sedation
Little Antimuscarinic therefore
No antimotion sickness

32
Q

What is Hydroxyzine used for?

A

Sedation and Antimusc
Antiemetic, Sedative
anxiolytic
skin allergies

33
Q

What is Meclizine used for?

A

Minimal Antimuscarinic Actions

Less sedating than hydroxyzine

34
Q

What is Promethazine for?

A

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

35
Q

Waht is the use of Cyproheptadine?

A

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

36
Q

What are the drug interactions of H1 Antihistamines?

A

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

37
Q

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

A
CYP2D6 and CYP3A4 ez in the liver
Imidazole antifungals
Cimetidine
Macrolides
H2 receptor antagonists
38
Q

What is different about the 2nd Gen H1 Antihistamines?

A
More selective for H1
Lower lipophilicity(less CNS)
Non-compeditive inhibitor
39
Q

What are the applications of Azelastine?

A

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

40
Q

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

A

Generally less sedative than 1st gen

41
Q

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

A

Levocetirizine and Cetirizine

42
Q

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

A

Fexofenadine

43
Q

Drug interactions of fexofenadine?

A

Dont take with antacids or citrus juices

44
Q

What meds stabilize mast cells and decrease degranlation?

A

Cromolyn and Nedocromil

45
Q

What is the MOA of Omalizumab

A

Binds IgE and keeps it from activting MAst cells

46
Q

Which Tricycliclic antidepressant acts as antihistamine?

A

Doxepin and Ketotifen