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Anesthesia Pharmacology > Histamine, Serotonin, Antacids... > Flashcards

Histamine, Serotonin, Antacids... Flashcards

(54 cards)

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1
Q

Does histamine cross the blood brain barrier?

A

No

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2
Q

What are the effects of histamine on H1 receptors?

A

REspiratory and GI smooth muscle contraction
Pruritis/sneezing
NO release by vascular smooth muscle

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3
Q

What are the effects of histamine bound to H2 receptor?

A

Increased GI secretion of H+

Increased HR/contractility

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4
Q

What is the effect of histamine on the H3 receptor?

A

decreased histamine synthesis and release

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5
Q

What are 5 generalized effects of histamine?

A 
Dilation of arterioles and capillaries
flushing
decreased systemic vascular resistance
decreased BP
increased Capillary permeability
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6
Q

H1 activation occurs at higher concentratrations of histamine than H2. T or F

A

false

H1 activation occurs at lower concentrations

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7
Q

T/F H1 activation decreases AV Node conduction

A

true

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8
Q

H1 activation causes coronary artery _________ while H2 activation causes coronary artery ______________

A

vasoconstriction

vasodilation

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9
Q

How does H2 activation affect the heart?

A

Causes catecholamine release from adrenal medulla
increases HR and contractility
coronary artery vasodilation

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10
Q

How does the skin respond to histamine?

A

dilated capillaries in affected area
Edema-increased capillary permeability
Wheal-dilated arteriols around edema

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11
Q

How do histamine antagonists work to treat allergic reaction?

A

block edema and pruritis but don’t block hypotension–give epi

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12
Q

t/f Histamine blockers act on both H1 and H2 receptors , are competitive inhibitors and are well absorbed orally.

A

F–act on one receptor or the other, not both

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13
Q

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

A

First generation also activate muscarinic cholinergic, serotonin and alpha receptors and can cause significant sedation.
Second generation H1 blockers act only on H1 receptors and cause much less sedation

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14
Q

At high doses Second generation H1 receptors may become ______________

A

non-competitive

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15
Q

What are side effects of first generation H1 blockers?

A 
Somnolence
Decreased alertness
slowed rxn time
Dry mouth
Blurred vision
urinary retention
impotence
tachycardia
Dysrythmias
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16
Q

What are teh side effects of second generation H1 blockers?

A

Q-T prolongation at high doses

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17
Q

What are clinical uses for H1 blockers?

A

Rhinoconjuctivitis
Bronchospasm (pretreat)
Anaphylactic/anaphylactoid rxns
motion sickness

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18
Q

Name 4 H2 blockers and their potency

A

Cimetidine (tagamet) potency=1
ranitidine (zantac) potency = 10
famotidine (pepcid) potency = 50
Nizatidine (Axid) potency=10

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19
Q

H2 blockers are rapidly absorbed orally, have minimal first pass metabolism, and cross both BBB and placenta. T/F

A

False. These drugs have extensive first pass metabolism and therefore are given at high doses

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20
Q

How are H2 blockers affected by pts with renal dysfunction

A

extends half life of drugs, so you shoud decrease the dose

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21
Q

What are clinical uses of H2 blockers

A

Treatment of duodenal ulcers
Allergy prophylaxis
Pre op med

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22
Q

What effects do H2 blockers have when given preop?

Study These Flashcards
A

decrease gastric volume

INcrease gastric pH

23
Q

What are most common H2 blocker side effects?

Study These Flashcards
A

diarrhea
headache
fatigue
malaise

24
Q

Prolonged use of H2 blockers may ______ gastric barrier to bacteria

25
Which H2 blocker binds and inhibits cytochrome p450?
cimetidine--It may also delay clearance of lidocaine due to a decrease in hepatic blood flow
26
How does cromolyn affect histamine? How is it used?
Inhibits antigen-induced release of histamine from mast cells Used as a phrophylaxis for bronchial asthma and is administered by inhalation
27
What type of drugs are omeprazole, protonix and prevacid?
H+ pump inhibitors
28
How do H+ pump inhibitors compare to H2 inhibitors?
Work longer (up to 24 hours) and give better results than H2 blockers
29
How are H+ pump inhibitors used for anesthesia?
as a pre op medicine they increase gastric pH, decrease gastric fluid volume. They must be given > 3 hours prior to surgery
30
Serotonin causes vasoconstriction in _________, _________, and ___________
cerebral, coronary and pulmonary
31
90% of serotonin is found in enterochaffin cells of _________, the rest is in ________ and _________
GI tract | CNS and platelets
32
Serotonin is Oxidized by ___________ and ________, and taken up by _________
liver and lungs | platelets
33
What does 5 HT1 cause. What is a drug that agonizes these receptors?
Cerebral vasoconstriction | Sumatriptan (Imitrex) revers middle cerebral artery vasodilation and improves migraine and cluster headaches
34
How do 5HT2 antagonists work?
Kentanserin attenuates vasoconstriction, bronchoconstriction and platelet aggregation, and acts as an alpha blocker
35
What conditions may be treated by 5-HT3?
N/V appetite addiction pain anxiety
36
How can you tell if a drug is a 5 HT3 antagonist?
ends in setron
37
What are side effects of Zofran?
headache diarrhea increased liver enzymes
38
How do antacids work?
acid+base=salt | at pH>5 pepsin is inactivated, LES tone is increased, and gastric contents are pushed forward
39
what are characteristics of sodium bicarbonate?
highly soluble rapid action in stomach for a brief duration May cause alkolosis Avoid in renal and heart pts. May increase sodium load
40
Magnesium hydroxide can cause acid rebound, and has a laxative effect. t/f
false. no acid rebound
41
What may happen with high doses of magnesium hydroxide?
Neuro/NM effects
42
Calcium carbonate is rapidly absorbed, can cause and acid rebound, and may cause hpercalcemia and metabolic alkalosis with chronic use. t/f
true
43
how is aluminum hodroxide absorbed? what may it deplete? HOw does it affect gastric emptying?
Minimally phosphate decreased
44
How do antacids affect other drugs?
increased delivery of PO medicines but decreased bioavailability
45
Antacids decrease incidence fo regurgitation and aspiration. T/f
f. no effect
46
What is an example of an antacid that may be given pre op?
bicitra (sodium citrate and citric acid)
47
How does sucralfate work? what is it used for?
reacts with HCL in stomach to form a viscous paste which forms a protective barrier in stomach. Used to treat duodenal and stomach ulcers
48
What are the effects of metoclopramide?
increases gastric emptying increase LES tone Relaxes pylorus and duodenum when the stomach contracts
49
What are side effects of metoclopramide. Which pts should they be avoided in?
``` may cause sedation, agitation, and dysphoria -give slowly or post induction Most common -dry mouth -abdominal cramping -dysrhythmias -extrapyramidal effects Rare -Hirsutism -Macropapular rashn With chronic use there is a prolactin association leading to breast enlargement and menstrual irregularities Don't give to GI obstruction Since it is a dopamine antagonist it should be avoided in parkinsons pts ```
50
how is metoclopramide eliminated?
renally
51
What are clinical uses of metoclopromide?
pre-op adunct anti-emetic gastroparesis therapy symptomatic GERD
52
Which patient needs metoclopramide?
``` full stomach trauma obese diabetic parturient ```
53
What are effects of Domperidone?
``` dopamine antagonist stimulates peristalsis increases LES tone Increase gastric emptying No cholinergic or central effects like reglan ```
54
What is cisapride (propulsin)? | How does it work?
gi Prokinetic | causes an increase in ACh and PS activity which increases gastric emptying. used for pts with gastroparesis

Anesthesia Pharmacology (25 decks)

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