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GI Systems & Antihistamines Flashcards

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1
Q

Name the two types of cells that secrete histamine. Where are these cells located?

A

Mast cells - skin, lungs & Gi tract

Basophils - circulation

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2
Q

What are the effects of histamine on the H1 versus the H2 receptor?

A

H1: Allergy
- smooth muscle contraction in respiratory and GI systems
- pruritus & sneezing
- NO release -> peripheral vasodilation
- Dec. AV node conduction -> bradycardia
-coronary vasoconstriction
H2: GI
-stimulate gastric H+ secretion
-increased myocardial contractility and HR
-coronary vasodilation

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3
Q

What is the effect of histamine at the H3 receptor?

A

Negative Feedback. It inhibits histamine synthesis/release. May have an overlap with H2 receptor

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4
Q

What happens if a patient gets an H2 blocker that also blocks the H3 receptor?

A

they will synthesize excess histamine. this is dangerous if the pt also gets a drug that evokes histamine release

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5
Q

What are the systemic effects of histamine release?

A

CV: flushing, hypoTN, dec SVR, capillary permeability- >edema
- pos chronotropic and inotropic effects, possible dysrhythmias
Resp: bronchoconstriction, esp in pts with asthma/ COPD
- inc prod of nasal/bronchial mucus
GI: constriction of intest. smooth muscle, inc bowel peristalsis and diarrhea
- inc gastric volume and acidity

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6
Q

What are symptoms of histamine antagonist toxicity?

A

Looks like anticholinergic poisoning, seizures, cardiac dysrhythmias

Anticholinergic effects= SLUDGE inhibitor like atropine(tachy,dry,blurred vision,urinary retention) -

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7
Q

What is the difference in first and second generation H1 antagonists?

A

1st gen = sedating, cognitive impairment, somnolence, sig. anticholinergic effects (SLUGE inhibitor like atropine)

2nd gen = non-sedating, do not cross BBB, minimal effects at muscarinic, cholinergic, and serotonin receptors

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8
Q

Identify the following as 1st or 2nd gen H1 bocker: Alegra, Benadryl and Claritin

A

Benedryl - 1st gen

Aelgra and Claritin - 2nd gen

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9
Q

What is Ranitidine (Zantac)?

A

H2 antagonist - inhibits gastric H+ secretion, decreased gastric volume has been shown as well

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10
Q

What is Famotidine (Pepcid)?

A

H2 antagonist - inhibits gastric H+ secretion, decreased gastric volume has been shown as well

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11
Q

What is the mechanism of action of Omeprazole (pilosec) and Pantoprazole (protinix)?

A

Proton pump inhibitor

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12
Q

True or false..Antacids increases pH and decreases gastric volume.

A

False. They neutralize GI acid content but have no effect on gastric volume

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13
Q

Antacids should be used with caution in what group of patients? Why?

A

Renal pts. they are usually Mg, Al, or Ca salts

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14
Q

What does magnesium hydroxide cause (“Milk of Magnesia”)?

A

osmotic diarrhea (Mg=Must Go)

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15
Q

What is aluminum hydroxide used for and what could it cause?

A

used for heartburn, sour stomach, peptic ulcer pain…some risk of constipation

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16
Q

How does giving bicitra lower mortality associated with acid pneumonitis?

A

increases the pH and decreases the volume of the aspirate

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17
Q

True or false..Metoclopramide increases pH and decreases gastric volume.

A

False. It stimulates upper GI motility and decreases gastric volume by accelerating clearance. It has no reliable effects on gastric acid pH.

It binds to or sensitizes cholinergic (muscarinic) receptors in GI system

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18
Q

In which patients is reglan contraindicated in and why?

A

Parkinson’s disease patients - it is a dopamine antagonist and can worsen symptoms an produce dystonic extrapyramidal side effects and akathes

also avoid in pts with seizures, MAOIs, TCAs

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19
Q

What receptor does zofran work at?

A

5HT3

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20
Q

What are the two uses for Droperidol and Haloperidol (Butyrophenones)?

A

anti-psychotics and anti-emetics

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21
Q

What is benedryl’s anti-emetic mechanis of action?

A

suppresses neuronal firing + anti-muscarinic+ sedative effects = effective for motion sickenss

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22
Q

What is promethazine (phenergan)? What is its mechanism of action?

A

antiemetic - blocks D2 receptor in CTZ and other parts of CNS

also sig anti-histamine and anticholinergic activity

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23
Q

What are the side effects of phenergan?

A

sedation, extrapyramidal symptoms (akathesia, dystonia), vascular necrosis

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24
Q

What is the mechanism of action of reglan?

A

Central D2 receptor and pro-kinetic

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25
What is the mechanism of action of scapolamine?
antagonize M1 receptors in cerebral cortex, pons; also block H1 receptor in hypothalamus, vomiting center
26
What are the side effects of scapolamine?
blurred vision, dry mouth, dizziness, agitation
27
What is the effect of histamine at the H3 receptor?
Negative Feedback. It inhibits histamine synthesis/release. May have an overlap with H2 receptor
28
What happens if a patient gets an H2 blocker that also blocks the H3 receptor?
they will synthesize excess histamine. this is dangerous if the pt also gets a drug that evokes histamine release
29
What is the difference in first and second generation H1 antagonists?
1st gen = sedating, cognitive impairment, somnolence, sig. anticholinergic effects 2nd gen = non-sedating, do not cross BBB, minimal effects at muscarinic, cholinergic, and serotonin receptors
30
Identify the following as 1st or 2nd gen H1 bocker: Alegra, Benadryl and Claritin
Benedryl - 1st gen | Aelgra and Claritin - 2nd gen
31
What is Ranitidine (Zantac)?
H2 antagonist - inhibits gastric H+ secretion, decreased gastric volume has been shown as well
32
What is Famotidine (Pepcid)?
H2 antagonist - inhibits gastric H+ secretion, decreased gastric volume has been shown as well
33
What is the mechanism of action of Omeprazole (pilosec) and Pantoprazole (protinix)?
Proton pump inhibitor
34
True or false..Antacids increases pH and decreases gastric volume.
False. They neutralize GI acid content but have no effect on gastric volume
35
Antacids should be used with caution in what group of patients? Why?
Renal pts. they are usually Mg, Al, or Ca salts
36
What does magnesium hydroxide cause ("Milk of Magnesia")?
osmotic diarrhea (Mg=Must Go)
37
What is aluminum hydroxide used for and what could it cause?
used for heartburn, sour stomach, peptic ulcer pain...some risk of constipation
38
How does giving bicitra lower mortality associated with acid pneumonitis?
increases the pH and decreases the volume of the aspirate
39
True or false..Metoclopramide increases pH and decreases gastric volume.
False. It stimulates upper GI motility and decreases gastric volume by accelerating clearance. It has no reliable effects on gastric acid pH. It binds to or sensitizes cholinergic (muscarinic) receptors in GI system
40
In which patients is reglan contraindicated in and why?
Parkinson's disease patients - it is a dopamine antagonist and can worsen symptoms an produce dystonic extrapyramidal side effects and akathes also avoid in pts with seizures, MAOIs, TCAs
41
What receptor does zofran work at?
5HT3
42
What are the two uses for Droperidol and Haloperidol?
anti-psychotics and anti-emetics
43
What is benedryl's anti-emetic mechanis of action?
suppresses neuronal firing + anti-muscarinic+ sedative effects = effective for motion sickenss
44
What is promethazine (phenergan)? What is its mechanism of action?
antiemetic - blocks D2 receptor in CTZ and other parts of CNS also sig anti-histamine and anticholinergic activity
45
What are the side effects of phenergan?
sedation, extrapyramidal symptoms (akathesia, dystonia), vascular necrosis
46
What is the mechanism of action of reglan?
Central D2 receptor and pro-kinetic
47
What is the mechanism of action of scapolamine?
antagonize M1 receptors in cerebral cortex, pons; also block H1 receptor in hypothalamus, vomiting center
48
What are the side effects of scapolamine?
blurred vision, dry mouth, dizziness, agitation
49
T or F. H1 antagonists are very selective and have vey little H2 activity.
True
50
H2 antagonists are primarily used for what?
gastric effects
51
What is used to block histamine-mediated vasodilation during anaphylactic rxns?
Diphenhydramine (Benedryl)
52
What is Hydoxyzine (Vistaril)?
A first generation H1 blocker - used for sedation/anxiety, motion sickness, vertigo, N/V - has significant anticholinergic effects
53
What does an H2 antagonist do?
inhibits gastric H ion secretion - decreased gastric volume has been shown as well
54
T or F. H2 antagonists have a duration of action of 6-10 hours that is followed by rebound hyper-secretion of gastric acid
True
55
Which of the following H2 antagonists bind to P-450? a. Ranitidine (Zantac) b. Cimetidine (Tagamet) c. Famotidine (Pepcid)
b.
56
What are the side effects of H2 antagonists?
diarrhea, fatigue, HA rare: cardiac dysrhythmias, mental status changes
57
What drug is characterized by the following: non-particulate antacid- used often in OB and other "full stomach" cases - unpleasant flavor (liquid)
Sodium citrate + citric acid (Bicitra)
58
What are the advantages of non-particulate antacids?
decreased likelihood of foreign body reactions, faster onset of action
59
What could happen with rapid administration of Reglan?
cramping
60
T or F. Reglan increases lower esophageal tone
True It is also used to treat diabetic gastroparesis and increase gastric emptying
61
Erythromycin is an antibiotic that many claim upsets their stomach. Why does this occur?
It works much the same way Reglan does. It increases lower esophageal sphincter tone and promotes GI motility It is also used to treat diabetic gastroparesis and increase gastric emptying (like reglan)
62
When dealing with PONV, you must first rule out 5 things. What are they?
``` hTN hypoxia hypoglycemia increased ICP gastric bleeding ```
63
What drug is characterized by the following: would be first choice for PONV prophylaxis if it was not for its "Black Box" warning
Droperidol
64
What drug is characterized by the following: "Black Box" warning: risk of torsades de pointes in pts with QT prolongation
Droperidol
65
What drug is characterized by the following: due to risk of vascular necrosis, it must now be given IM or else as an IV infusion
Promethazine (Phenergan)
66
What drug does Dr. Volts like to give to pts with blood in their stomach (tonsillectomy, ENT stuff etc)?
Reglan
67
What 2 antiemetics can cause extrapyramidal symptoms?
Reglan and Phenergan
68
What are side effects of Reglan?
hypoTN, tachycardia | dyskinetic/extrapyramidal symtoms at high doses tx w/ benzos and antihistamines
69
T or F. Ephedrine has anti-emetic properties.
good evidence is lacking but n/v results from hTN so it may help by inc BP
70
What are some other antiemetic treatments?
supplemental O2, hydration, inhaled isopropyl alcohol, ginger, P6 (wrist) acupressure, TENS (transcutaneous electrical nerve stimulation)
71
Name the 2 receptors at the vestibular center that are involved in PONV.
H1, M1
72
Name the 5 receptors in the CTZ that are involved in PONV.
D2, M1, H1, 5-HT3, & NK1
73
What effects cortical afferent nerves that leads to PONV?
``` hTN hypoxia increased ICP pain unpleasant sights, smells and emotions ```
74
Name the 3 receptors of the afferent nerves of the periphery (vagal and glossophayngeal nerves, GI tract nerves, and pharyngeal nerves) that are involved in PONV.
5-HT3, D2, NK1
75
What are the systemic effects of histamine release?
CV: flushing, hypoTN, decreased SVR, capillary permeability- >edema - pos chronotropic and inotropic effects, possible dysrhythmias Resp: bronchoconstriction, esp in pts with asthma/ COPD - inc prod of nasal/bronchial mucus GI: constriction of intest. smooth muscle, inc bowel peristalsis and diarrhea - inc gastric volume and acidity

Pharmacology (22 decks)

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