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Exam 1 Pharm II > Antihistamines > Flashcards

Antihistamines Flashcards

1
Q

What do these two drugs do?
Cromolyn Sodium
Nedocromolin

A

Prevent histamine release.

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2
Q

What effect does ACh have on histamine?

A

Induces histamine release from mast cells

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3
Q

What effect do B-adrenergic agonists have on histamine?

A

Inhibit histamine release

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4
Q

What type of receptor class do Histamine receptors belong?

A

All 4 are G-coupled receptors

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5
Q

H1 Receptors are found…..?

A

CV, Resp. Sys., GI smooth mm.

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6
Q

What effect does histamine have on the IP3 pathway?

A

When linked to the phosphoinositol pathway, activation causes contraction of smooth muscle.

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7
Q

Outline the cellular signal pathway starting with H1 that causes smooth muscle contraction.

A

Histamine+H1==>Gq==> PLC==>IP3+DAG==>Increaseed Ca2+==> Increased Ca2+-Calmodulin==> Phosphorylation of Myocyte Light chains (MLC)

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8
Q

The H1 receptor causes__________Via_______release from the vascular smooth muscle===> Increase cGMP==> Decreased Ca++.

A
  1. Vasodilation

2. NO

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9
Q

What other reflexes does the H1 receptor enable?

A

Sneezing and itching (pruritis). (Sensation from sesory nerve endings

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10
Q

What role does the H2 receptor play?

A

Linked to relaxation of vascular smooth muscle and gastric secretions. also reduces histamine release from mast cells as a negative feedback loop.

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11
Q

Where is the H2 receptor distribited?

A

CV, GI smooth muscle, Stomach

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12
Q

Colocalization of H1 and H2 receptors causes?

A

H1 in vasc. endothelium==> Increased NO release and contraction of the endothelial cells.
H2 in vascular muscle===> causes relaxation (vasodilation)

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13
Q

Where are H3 receptors found?

A

In the CNS

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14
Q

What role does the H3 receptor play in the brain?

A

Linked to inhibition of NT release.

(Hist===>H3====> Decreased Ca++) Gi coupled!

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15
Q

Where the hell are H4 receptors located?

what’s their role?

A
  1. On mast cells, basophils and eosinophils.

2. Linked to hista,mine-induced chemotaxis

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16
Q

What do the H1 and H2 receptors do in the CV system?

A

H2: Moderate increase in rate and force of contraction.

Vasodilation (H1 in endothelium and H2 in smooth muscle.

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17
Q

What histamine receptor is in the resp. sys and how does it work?

A

H1 mediated bronchial constriction of smooth muscle.

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18
Q

What histamine receptor is in the stomach and how does it function?

A

H2 mediated acid release from parietal cells of stomach

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19
Q

What effect does histamine have on the heart?

A

Positive chronotropy and ionotropy.

20
Q

Cardio crap: Define Chronotropy and Ionotropy.

A

Chronotropy affects the heart rate.

Ionotropy affects force of heart contraction.

21
Q

Outline pathway of how H2 receptor modulates chronotropy?

A

Hist+H2R==>G-couple»» AC…..Increase cAMP which binds to and opens HCN channel allowing Na+ influx. cAMP+PKA bind L-type Ca++ channel allowing Ca++influx into cell.
In inotropy, Histamine binds….G-coupled signaling….L-type Ca++ channels open=Contraction (No HCN)

22
Q

What does histamine do do veins?

A

Constricts them

23
Q

What effect does histamine have on capillaries?

A

Increases permeability. H1=Endothelial contraction, H2=Vascular smooth muscle relaxation.

24
Q

List pathologies caused by histamine

A

Urticara-Hives, rash, edematous welts
Dermatographia- Redness on mechanical stimulation.
Flushing- Due to vasodilation or seeing bae.

25
Q

Histamine causes_______ in the respiratory system via_______. This receptor uses________as second messengers.

A
  1. Broncocontriction
  2. H1
  3. Gq, IP3, DAG.
26
Q

Anaphylaxis is treated with?

A

Epinephrin (Epi-Pen)

27
Q

Differentiate H1 and H2 receptor antagonists

A

H1 antagonists are reffered to as antihistamines (Don’t bind H2)
H2 antagonists are referred to as acid blockers (don’t bind H1 receptors)

28
Q

What is an inverse agonist?

A

This is basically a clown agent that binds a selected receptor like an agonist would but instead of causing an agonist effect, it does the exact opposite. (SO structurally these guys have to retain a structure very close to histamine)

29
Q

Name the 1st gen antihistamine classes.

A 
Alkymines
Ethanolamines
Ethylenediamines
Phenothiazides
Piperadines
Piperazines
30
Q

Give examples of 1st gen antihistamines

A 
Bromopheniramine
Cyproheptadine
Diphenhydramine
Promethazine
Hydroxyzine
Pyrilamine
31
Q

What effct do H1 antagonists have in the CNS?

A

They have sedative effects as the block H1/H2 receptors in the brian which are important in wakefulness.

32
Q

Which H1 class of drugs are the most sedative?

A

Ethanolamines and phenothiazines (ie diphenhydramine, promethazine)-Older H1 antagonists are sedating (someday we won’t have to give a shit about old drugs)

33
Q

What other effect do H1 antagonists have?

A

Anticholinergic effects (atropine-like effects) only in 1st gen drugs.
Anti-motion sickness and antiemetic effects likely derived from anti cholinergic effect (Promethazine is potent ; Scopalamine-like)
Also cause typical anticholinergic effects: Dry mouth, decreased urination

34
Q

Which 1st gen drugs are used as local anesthetics?

A

Pyrilamine, Promethazine

35
Q

Which H1 antagonists have anti-serotonin activity? Used for?

A

Cyproheptadine, azatidine

Antipruritic

36
Q

Which drugs H1 antagonists have Alpha adrinergic antagonism? Used for?

A

Phenothiazines, Used for hypertension

37
Q

Which H1 antagonists have extrapyramidal activity? used for?

A

The Phenothiazine; promethazine

Dystonia, akathisia

38
Q

Name the 2nd generation H1 antagonists!

A 
Loratadine (Claitin)
Desloratadine(Clarinex)
Fexofenadine(Allegra)
Cetirizine(Zyrtec)
Terfidine (Seldane)
39
Q

Difference between the 1st gen and second gen H1 antagonists

A

1st Gen H1 antagonists=Lipid soluble, CNS effects, not very selective
2nd gen= Low lipid solubility, little/no sedation, no antimuscarinic activity, no anti-emetic activity, no anti-motion sickness activity. Efflux from CNS via P-glycoprotein transporter

40
Q

What other effects does Cetrizine (zyrtec) have?

A

Blocks: LTC4, Neutrophil migration, Eosinophil infiltration (H4 block maybe?)

41
Q

What is Olopatadine? Whst is it used for?

A

2nd gen H1 antagonist eye drops

42
Q

What are azelastine and Ketotifen?

A

Azelastine and Ketotifen are H1 antihistamines used as eye drops in the US to relieve eye irritation.

43
Q

Name the 3 antihistamine drugs to treat motion sickness.

A

Dimenhydinate (Diphenydramine+Chlorotheophylline), Meclizine

Promethazine

44
Q

Which antihistamines cause sadation?

A

Ethanolamines
Phenothiazines
These may interact with other sedatives (alcohol, anxilytics, antipsychotics

45
Q

What are 1st gen antihistamines contraindicated in?

A

Urinary retension, narrow angle glaucoma

Exam 1 Pharm II (8 decks)

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