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28 Cards in this Set

  • Front
  • Back
1. Created inside mast cell and basophils
2. Created from a.a. histidine
3. Also found in CNS as neurotransmitter.
H1 histamine receptors
1. Linked to Gq/11
2. stimulation of PLC
3. mediates most allergic rxns
H2 histamine receptors
1. linked to Gs
2. stimulation of of adenylyl cyclase
3. present on gastric parietal cells
4. mediates gastric acid secretion
What causes the release of histimine?
1. released from mast cells and basophils as part of the inflammatory response.
2. also released in response to IgE as part of allergic rxn and anaphylaxis rxn.
Histidine's effect on CV
1. relaxes smooth muscle to decrease BP
2. increase vascular permeability in venules--> edema.
Histidine's effect on smooth muscles
Contracts bronchial and most intestinal smooth muscles.
Histidine's effect on stomach parietal cells
Stimulates gastric acid secretion, contributing to ulcers.
Effect on skin?
"Wheal" or hives due to edema from increased permeability.

Bright red due to vasodilation.
Drugs that affect histamine actions?
H1 receptor antagonists:

1. benadryl
2. zyrtec
3. claritin
4. allegra

H2 receptor antagonists
1. tagamet
2. zantac
3. pepcid
First generation sedating

Competitive reversible blockade of H1 receptors.
Clinical uses of benadryl
Tx allergic rxn and bronchospasms due to anaphylaxis.

Also act as secondary antiemetic and antivertigo actions.

For sleep
Tx motion sickness and vertigo

A salt of benadryl
"Second generation" Non-sedating Histamine H1 receptor antagonists are?
1. zyrtec
2. claritin
3. allegra
What is mechanism for the drugs above?
They DO NOT cross blood brain barrier.

No recognition of muscarinic receptors.

Prevents action on CNS muscarinic and dopamine receptors.

Selective, competitive reversible blockade of H1 receptors.
Side effects of First generation vs. Second generation?
First generation: Penetrates CNS and cross reactivity of muscarinic cholinergic receptors.

Second generation: side effects greatly reduced due to no CNS penetration and limited cross reactivity of muscarinic receptors.
What are some examples of H2 Histamine receptor antagonists of first and second generation?
First generation: Tagamet

Second generation: Zantac and Pepcid
Mechanism of pepcid and zantac?
Selective, competitive reversible blockade of H2 receptors.
Clinical uses of pepcid and zantac?
1. Tx of ulcers
2. Tx of immediate hypersensitivity rxn
Side effects of G1 or Tagamet?
Inhibits P450s, therefore affects clearance of drugs.
Mechanism of Prednisone
A glucocorticoid

Bind to glucocorticoid receptor leading to transcriptional regulation of genes.

Basically, its effects are inside the nucleus.
Clinical uses of prednisone
1. allergy
2. bronchial asthma
3. inflammation
4. autoimmune diseases
Side effects of prednisone or glucocorticoids in general?
1. Cushing's syndrome
2. acute adrenal insufficiency due to abrupt withdrawal
Examples of immunomodulary agents?
1. Interferon Beta-1a (avonex)
2. Interferon Beta-1b (betaseron)
Mechanism of action of immunomodulary agents
Bind to cell surface receptor

Induces a cascade of signaling pathways

Causes production of IFN stimulated gene products
What are the functions of IFN stimulated gene products?
1. antiviral
2. antiproliferative
3. causes anti-inflammatory effects
4. reduction in T cell activation
5. decreases cytokines
6. decreases T cells entry into CNS
Clinical uses of immunomodulary agents?
Multiple sclerosis
Side effects of immunomodulatory agents?
Generation of neutralizing antibodies

NOTE: IFN beta-1a is glycosylated while 1b is not.