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Pharm II: Exam 1 > Histamine > Flashcards

Histamine Flashcards

(56 cards)

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1
Q

Where are histamine located?

A

Found throughout many tissues, MAINLY in Mast cells (Highest amounts are found in the lung, skin, nasal; gastrointestinal mucosa)

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2
Q

How is Histamine synthesized and stored?

A

Formed by decarboxylation of the amino acid histidine and stored in granules

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3
Q

How are Histamines released?

A

Released along with several chemical mediators during episodes of trauma, allergies, anaphlyaxis, colds, bacterial toxins, bee sting venom, drugs

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4
Q

What are the two types of histamine release?

A
  1. Cytolytic: plasma membrane is damaged causing leakage of cytoplasmic contents (no energy dependent, no calcium required)
  2. Noncytolytic: exocytotic release from granules (no damage to mast cell, requires energy and calcium - IgE antibodies bind to antigen and release histamine)
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5
Q

What drugs are inducers of Cytolytic release of Histamine?

A
  • Phenothiazines
  • Narcotic analgesics
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6
Q

What substances and drugs stimulate Histamine release from Mast cells?

A
  • Radiocontrast media
  • D-Tubocurare
  • Mast cell degranulation protein (from bee venom)
  • Morphine
  • Codeine
  • Succinylcholine
  • Protamine
  • Doxorubicin
  • Vancomycin
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7
Q

What is Red Man Syndrome? What are associated S/Sx? How do you treat?

A

Related to reactions with Vancomycin may cause:

  • Flushing
  • Pruritus
  • Chest pain
  • Muscle spasm
  • Hypotension

Pretreatment with antihistamine attenuates the symptoms

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8
Q

Which drugs are Mast cells stabilizers (prevent noncytolytic degranulation and histamine release)?

A
  • Cromolyn
  • Nedocromil
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9
Q

How are Cromolyn and Nedocromil administered?

A

Inhalation of a powder

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10
Q

T or F: Cromolyn and Nedrocromil is useful in management of acute asthma attacks.

A

F; Only used prophylactically to BLOCK asthmatic reactions, DEC symptoms of allergic rhinistis, Effective only if used before a challenge not during.

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11
Q

How many types of histamine receptors are known? What are they?

A

4 different types:

  • H1: phospholipase C mechanism
  • H2: adenylyl cyclase mechanism parietal cell acid secretion
  • H3: inhibit the release of histamine on neurons (feedback inhibitions)
  • H4: Proinflammatory activity
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12
Q

What is histamines role in Allergies and Anaphylaxis?

A
  • Stimulation of secretions
  • Constriction of smooth muscle
  • Stimulation of sensory nerve endings
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13
Q

How does Histamine stimulate secretions at H1 receptors?

A

INCs mucus in nasal cavity and bronchi (results in respiratory symptoms)

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14
Q

How does Histamine stimulate secretions at H2 receptors?

A

Stimulates gastric acid secretion

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15
Q

How does histamine constitute constriction of smooth muscle?

A

H1 receptors constrict bronchi and intestines (causes cramps and diarrhea)

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16
Q

T or F: Healthy human’s histamine will causes hyperreactivity

A

F; healthy human’s histamine is not especially potent but in patients with asthma the bronchi are hyperreactive.

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17
Q

Which histamine receptor is responsible dilation of smooth muscle in blood vessels; How does histamine affect these processes?

A

H1; DEC blood pressure and INC nitric oxide (vasodilation)

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18
Q

Which histamine receptors stimulate heart rate and contractility? How does histamine affect these processes?

A

H1 & H2; Directly INCs via INC influx of calcium, Indirectly INC via baroreceptor-mediated INC in sympathetic tone

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19
Q

Where are catacholamines released from in the body?

A

Adrenal glands

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20
Q

Which histamine receptors are responsible for dilation and INC’d permeability of capillaries? How does histamine affect these processes

A

H1 & H2; causes endothelial cells to contract and expose permeable basement membrane (leaks protein and fluid)

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21
Q

What is the “Triple response of Lewis”?

A

Positive skin test, challenge with an allergen (bugbite, histamine, allergy test)

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22
Q

What are the three presentations of “Triple Response of Lewis”?

A
  • Red Line/Spot (Dilates arterioles where injected)
  • Flare (Histamine stimulates nerve endings which leads to dilation of arterioles)
  • Wheal (INC in capillary permeability due to local edema)
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23
Q

What are the principal targets in a hypersensitive reaction?

Study These Flashcards
A
  • Mast cells
  • Basophils
24
Q

What happens in an allergic response?

Study These Flashcards
A

Antigen produces formation of IgE antibodies bind with high affinity receptor specific for IgE and activate tyrosine kinase –> INC in intracellular calcium (triggers exocytosis of secretory granules in the mast cells)

25
What **other mediators of inflammation** are released?
**Phospholipase A2**: produces leukotrienes (contract smooth muscles of the bronchi) and prostagladins
26
What are the **main differences** are between **allergic reactions** and a **anaphylatic response**?
* Releasing locations * Rates of release
27
**T or F**; Response remains localized if histamine release is in a specific area.
T
28
What will happen if histamine is **released rapidly** and **diffuses into the blood**?
**Anaphylatic reaction** (systemic response)
29
What will a **patient presents** with who is experiencing a **hypersensitiveity reaction**?
* Intense warmth * Skin reddens * Marked effec on palms, hands, face, scalp and ears * Hives * Nausea * DEC BP * INC HR * Bronchospasm * Constriction
30
How can **(true) anaphylaxis** reaction treated?
Epinephrine
31
Which drugs are considered **1st Generation Histamine H1 Blockers**?
* Triprolidine * Diphenhydramine * Promethazine * Hydroxyzine * Chlorpheniramine
32
Which drugs are considered **2nd Generation Histamine H1 Blockers**?
* Loratadine * Desloratadine * Azelastine * Cetirizine * Fexofenadine
33
What are differences between **1st and 2nd generation H1 blockers**?
* **1st generation** * *anticholinergic* * *short-acting* * *CNS penetration* * **2nd generation** * *no anticholinergic activity* * *Long-acting* * no CNS penetration (does not cross BBB)
34
What are characteristics of **H1 blockers**?
**Antagonize all actions of histamine** (reversible, competitive blockers of H1 receptors – action via H2 receptor still active) mainly blocking the effects of histamine on: * INC permeability * Edema formation * Itching
35
**T or F**; H1 blockers have great effect on actions bronchoconstriction and vasodilation
**F**; these actions are predominantly caused prostaglandins and leukotrienes
36
Does **H1 Blockers** have tolerance to suppressive effects on skin test reactivity to allergens? Tolerance to sedative effects?
**No**, concentration achieved at sites unknown with significant inhibition of wheal and flare response for 26 hours (residual suppression may last for up to 7 days after discontinuation of H1 blockers following 1-2 week regular use); Tolerance to sedative effects may occurs (theraputic effect may be restored with swith to another antihistamine class)
37
What is the importance of **active metabolites** of **2nd generation H1 blockers**?
**Theraputic uses** (Desloratadine=Clarinex, Fexofendaine=Allegra)
38
**T or F**: All FDA-approved antihistamines do not prolong the QT interval
T
39
What are **theraputic uses** for antihistamines?
* Allergic reactions * Prevention of Motion Sickness * Prevention of Nausea/Vomiting * Sedative * Antiparkinsonism * Local anesthetic action
40
How are **antihistamines** useful in **preventing motion sickness**?
Possibly related to anticholinergic effects; **administered 1 hour prior to anticipated motion**
41
What **antihistamine medications** are available for **prevention of motion sickness**? Which are most effective?
* Promethazine (**most effective**) * Scopolamine (**most effective, _non-antihistamine_**) * Diphenhydramine * Mecilizine * Cyclizine
42
What **antihistamine medications** are available for **prevention of nausea/vomiting**? How do these medications work?
Block dopamine D2 receptors * Promethazine * Timeprazine
43
What **antihistamine medications** are available as **sleep medications**?
* Diphenhydramine * Doxylamine * Doxepin
44
What is the **limit** for tolerance of **antihistamines medications** used for **sedative purposes**?
**10 consecutive** nights of use
45
What **antihistamine medications** are available that have **antiparkinsonism effects**?
* Diphenhydramine
46
What **antihistamine medications** are available with **local anesthetic actions**? How do these medication have this effect?
**Block sodium channels** * Promethazine (sunburn preparation) * Magic Mouthwash (TX oral ulcers, infections, inflammation, and pain)
47
What are all the **actions** of **diphenhydramine**?
* H1 Blocker (1st Generation) * Motion Sickness * Sedative effects (Sleep medication) * Antiparkinsonism effects
48
What are all the **actions** of **Promethazine**?
* H1 Blocker (1st Generation) * Motion Sickness * Nausea/Vomiting * Local Anesthetic
49
What are **ADRs** for **Antihistamines**?
* Antimuscarinic * Sedative actions (absent/lower with 2nd generation H1 Blockers)
50
What **sedative effects** might a patient present with when taking **antihistamines**?
* Fatigue * Dizziness * Blurred vision
51
What determines the **CNS sedation** of a person on **Antihistamines**?
**Effect correlates with H1 receptor binding in the brain** (i.e. Doxepin=50-90% CNS bound, Fexofenadine 0% bound)
52
What **antimuscarinic** effects might a patient present with when taking **antihistamines**?
* Dry mouth and nasal passages * Constipation * Blurred vision * Urinary retention
53
**T or F**: Paradoxial excitation may occur in children taking antihistamines.
T
54
What **drug interactions** are known with **antihistamines** (H1 blockers)?
Could potentiate other CNS depressants
55
What are **possible toxicities** with **antihistamines** (H1 antagonist)?
OD is rare but **acute poisoning is relatively common** (esp. in children)
56
What are **acute poisoning effects** experienced with **antihistamines**?
* Initial excitement * Ataxia and convulsions * Coma and cardiorespiratory collapse

Pharm II: Exam 1 (7 decks)

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