Lecture 09_Spring Flashcards
Name the two types of cells that secrete histamine. Where are these cells located?
Mast cells - skin, lungs & Gi tract
Basophils - circulation
What are the effects of histamine on the H1 versus the H2 receptor?
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
What is the effect of histamine at the H3 receptor?
Negative Feedback. It inhibits histamine synthesis/release. May have an overlap with H2 receptor
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
What are the CV effects of histamine release?
- flushing
- hTN
- decreased SVR
- capillary permeability- > edema **
- pos chronotropic and inotropic effects
- possible dysrhythmias
What are symptoms of histamine antagonist toxicity?
Looks like anticholinergic poisoning, seizures, cardiac dysrhythmias
Anticholinergic effects= SLUDGE inhibitor like atropine (tachy,dry,blurred vision,urinary retention)
What is the difference in first and second generation H1 antagonists?
1st gen = crosses the BBB => 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
Identify the following as 1st or 2nd gen H1 bocker:
Alegra
Benadryl
Claritin
Benedryl - 1st gen
Aelgra and Claritin - 2nd gen
What is Ranitidine (Zantac)?
H2 antagonist - inhibits gastric H+ secretion, decreased gastric volume has been shown as well
dosing = 50mg IV
What is Famotidine (Pepcid)?
H2 antagonist - inhibits gastric H+ secretion, decreased gastric volume has been shown as well
dosing = 20mg IV
What is the mechanism of action of Omeprazole (pilosec) ?
Proton pump inhibitor
True or false..Antacids increases pH and decreases gastric volume.
False. They neutralize GI acid content but have no effect on gastric volume
How does giving bicitra lower mortality associated with acid pneumonitis?
increases the pH and decreases the volume of the aspirate
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 akathesalso avoid in pts with seizures, MAOIs, TCAs
What receptor does zofran work at?
5HT3
What are the two uses for Droperidol and Haloperidol (Butyrophenones)?
anti-psychotics and anti-emetics
What is benedryl’s anti-emetic mechanis of action?
suppresses neuronal firing + anti-muscarinic+ sedative effects = effective for motion sickenss
What are the side effects of phenergan?
- sedation
- extrapyramidal symptoms (akathesia, dystonia)
- vascular necrosis - must be given IM or IV infusion
What is the mechanism of action of reglan?
Pro-kinetic: Binds to or sensitizes cholinergic (muscarinic) receptors in GI system and stimulates upper GI motility -> accelerated clearance which decreases gastic volume
Anti-emetic: Central D2 receptor antagonist
Dopamine antagonist, but dopamine inhibition is NOT primary mechanism of action - May partially explain anti-emetic effect – binding D2 receptors in the CTZ
What are the side effects of scapolamine?
blurred vision, dry mouth, dizziness, agitation
Antacids should be used with caution in what group of patients? Why?
Renal patients bc they are usually Mg, Al, or Ca salts
What magnesium hydroxide (“Milk of Magnesia”), what is it taken for and what does it cause?
it is taken for constipation bc it causes osmotic diarrhea (Mg=Must Go)
it is an antacid - neutralizes GI acid content (no effect on gastric volume)
What is aluminum hydroxide, what is it used for and what could it cause?
Also called Mylanta - is an antacid that is used for heartburn, sour stomach, peptic ulcer pain…some risk of constipation