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Pharmacology -- Test #5 > Antihistamines > Flashcards

Antihistamines Flashcards

1
Q

Four things other than histamine in a mast cell storage granule?

A
  1. Sulfated-polysaccharide
  2. Heparin Sulfate
  3. Chondroitin Sulfate
  4. Proteases
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2
Q

Causes of non-antigen mediated mast cell release

A 
Thermal or Mechanical Stress
Cytotoxic Agents (Venoms)
Drugs (high dose morphine)
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3
Q

What happens when an H1 receptor is activated (molecularly)

A

Gq –> PLC –> IP3+DAG –> increased Ca –> Calmodulin binding –> phosp. MLC

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4
Q

What does H1 receptor activation do (in the context of tissues

A

Contraction of the smooth muscle

Important in the CV, Resp., and GI systems

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5
Q

How does H1 activation trigger vasodilation

A

In vascular endothelial cells it acts of increase NO release. NO diffuses to vascular smooth muscle and increases cGMP. Higher cGMP will lower the Ca, relaxing the muscles.

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6
Q

What happens when an H2 receptor is activated (molecularly)

A

Gs –> Inc. adenylate cyclase –> Inc. cAMP

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7
Q

Important roles of H2 activation?

A

Relaxation of Vascular Smooth muscle (don’t confuse with H1 in the vascuar endothelium)
Triggers Gastric Secretion

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8
Q

Role of H3 receptors?

A

Autoreceptor in neurons that use His as a transmitter that inhibits NT release

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9
Q

Role of H4 receptors?

A

Located on mast cells, basophils, and eosinophils

May be in future anti-inflammatories, none out now though

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10
Q

Effects of Histamine on the CV system

A

Heart – Inc rate and force of contraction

Vasodilation

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11
Q

Effects of Histamine on the Resp system

A

H1 med. Constriction of the bronchial sm. muscle

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12
Q

Effects of Histamine on the digestive?

A

H2 mediated acid release from parietal cells

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13
Q

Massive Histamine release can trigger _____. Treat with ______

A

Anaphylaxis

Ephinephrine

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14
Q

Which Histamine receptor(s) are important for Vasodilation? Endothelial contraction?

A

Vaso – H1 and H2

Endo – H1

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15
Q

Triple response of histamine

A
  1. Red spot at the point of injection (immediate)
  2. Red flare radiating (1 cm, happens 10 s later)
  3. Wheal (reised welt) at injection site
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16
Q

Aside from the triple response, what other skin pathologies are Histamine driven

A

Urticaria
Dermatographia
Flushing (erythema)

17
Q

Describe urticaria

A

Hives, Rash, Edematous Welts

18
Q

Six important examples of first generation antihistamines

A 
DIPHENHYDRAMINE
Promethazine
Hydroxyzine
Brompheniramine
Pyrilamine
Cyproheptadine
19
Q

Important molecular structural info on first gen H1 antagonists

A

Need an amino group

DON’T need an amidazole group

20
Q

What types of 1st gen H1 blockers have the strongest sedative effcts

A

Ethanolamines and Phenothiazines

21
Q

What types of 1st gen H1 blockers have the strongest anti-cholinergic effcts

A

Diphenhydramine, Promethazine

22
Q

Why give a shit that 1st gen H1 blockers have anti-cholinergic effects?

A

anti-motion sickness/vertigo effect
Anti-emetic effect
Not seen in 2nd gen

23
Q

Which 1st gen H1 blockers have local anesthetic effects? weak alpha adrenergic antagonism?

A

anesthetic – pyrilamine, promethazine

alpha-adrenergive – phenothiazines

24
Q

Four main examples of 2nd gen H1 antagonists

A

Loratadine (Claritin)
Desloratadine (Clarinex)
Citirizine (Zyrtec)
Fexofenadine (Allegra)

25
Q

How do second gen H1 blockers decrease lipid solubility

A

Efflux from CNS by P-glycoprotein transporter

26
Q

Aside from H1 blocking, Cetirizine may have effects on ___- receptors, leading to…

A

H4

LTC4, Neutrophil Migration, Eosinophil Infiltration

27
Q

Three main examples of topical (eye drops and nasal spray) H1 receptor antagonists

A

Olopatadine
Azelastine
Ketotifen

28
Q

Four primary clinical uses of H1 antagonists

A
  1. Seasonal and perennial allergic rhinoconjunctivitis
  2. Chronic Urticaria
  3. Motion Sickness
  4. Adjunct with epinephrine to treat anaphylaxis
29
Q

Three H1 antag. drugs used for motion sickness

A
  1. Dimenhydrinate (benedryl + chlorotheyphyllline salt)
  2. Meclizine (Antivert TM)
  3. Promethazine (Phenergan)
30
Q

Relationship of epi and his

A

epinephrine is a physiological antagonist to histamine

31
Q

Due to antimuscarinic effects, 1st gen H1 blockers are contraindicated in

A

Urinary Retention and Narrow Angle Glaucoma

32
Q

Adverse drug interactions of Phenothiazine?

A

Dystonia
Akathisia (restlessness)
Parkinsonian Rigidity

33
Q

How do H1 antagonists alter wakefulness

A

They block H1 receptors of the thalamic relay cells, leading to hyperpolarization, bursts of action potentials, and sleep

Pharmacology -- Test #5 (12 decks)

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