Chapter 10: Alpha Antagonist Drugs Flashcards
Test 2
Alpha antagonists =
Alpha blockers
What is the Alpha Blocker MOA?
Bind to the receptor and block the natural ligand effects
What is the only irreversible Alpha-Blocker?
Phenoxybenzamine
What is Pheochromocytoma?
Tumor that overproduces epinephrine
Located in GI tract and adrenomedulla
Tx: Pheochromocytoma
Non-selective Alpha antagonists
Phentolamine
Phenoxybenzamine
decreases BP so tumor can be operated on
T/F: Alpha Blockers can cause reflex tachycardia
T
Tx: BPH
Alpha Blockers
-osin drugs
Drug: Labetalol
Mixed Alpha/Beta blocker
Racemic Mixture
Vasodilation, decrease HR, decrease contractility, decreased CO
Drug: Phenotolamine
Alpha Blocker
Competetive antagonist
Vasodilation
reflex tachycardia
Minor adverse effects: Abd pain, N/V
Tx: Male erectike dysfunction
Alpha Blocker
Phentolamine
Has to inject directly into penis
Can cause priapism - erection that doesnt go away**
Drug: Phenoxybenzamine
Alpha blocker
forms covalent bonds
inhibits NE reuptake
will make orthostatic BP worse
Drugs: Prazosin
Alpha Blocker A-1 Specific
Low affinity for A-2 = no reflex tachycardia
Tx: HTN; BPH
-works in the arteries and veins
What is BPH?
Overgrowth of the prostate gland
T/F: -osin Alpha-blockers are A-1 specific
T
What effects do Beta blockers have?
negative inotropic
negative chronotropic
How can you identify a Beta blocker?
-olol
What is the beta blocker prototype?
Propranolol
Which beta blocker has a bioavailability of 0? what does this mean?
Esmolol
Cant give PO
What are some general characteristics of Pharmacokinetics of beta blockers?
A: Peak: 1-3 hrs
D: half life: 3-10 hrs
M: bioavailability: low 30-60%
E: vary
Where do beta blockers work?
Heart - Beta receptors in the cardiac myocytes
Inotropic =
Force
contractility
Chronotropic =
Rate
How does beta blockers effect the lungs?
constricts bronchioles
How does beta blockers effect the eyes?
Decrease IOP
How does chronic use of beta blockers effect Lipoproteins?
Increases VLDL and decreases HDL = bad
Drugs: Propranolol
Beta blocker – PROTOTYPE
B1/B2
IV only - 1st pass metabolism extensive
Inderal LA is long acting version
Drugs: Metoprolol and Atenolol
Beta Blockers
B1 specific
Safer in pts with Asthma & DM
Which Labetalol isomers are nearly inactive?
S,S
R, S
Which Labetalol isomers are a potent Beta blocker?
R,R
Which Labetalol isomers are a potent A1 blocker?
S,R
Drugs: Esmolol
Beta Blocker
B1 specific
Ultra short acting/rapid
Safer for critically ill
0% bioavailability = IV steady state infusion
Tx: Intraoperative tachycardia, SVT
What are Beta Blocker Indications
HICOD
HTN
Ischemic Heart Disease
Cardiac Arrhythmias
Obstructive Cardiomyopathy
Diessecting aortic aneurysm
How should you stop taking beta blockers?
d/c gradually
What are 2 important signs of toxicity?
Worsening of asthma (B2 blocker - constricts)
Hypogylcemia in DM
What is a SE of Alpha-1 Blockers?
Salt and water retention
More effective when used in conjunction with Beta blockers and diuretics and vice versa
What are your 4 types of Vasodilators?
Oral
Parenteral
Combination
Nitrates
How do nitrates work?
Release Nitric Oxide in the endothelium
Drugs: Hydralazine
Vasodilator
Induces NO production in endothelium
low bioavailability
rebound tachycardia
Tx: HTN
Drugs: Minoxidil
Vasodilator
K+ channel activation, hyperpolarization of smooth muscles
Rogaine– SE: will grow hair
What vasodilator will cause hair growth?
Minoxidil
Drugs: Nitroprusside
Vasodilator
Breaks down to release NO in blood stream
Works on arteries and veins
Protect from light
Continuous IV infusion
Tx: HTN emergency, Cardiac Failure
What happens with Nitroprusside toxicity?
Cyanide accumulation/posioning
What organ eliminates CN-?
Kidneys
Should you give Nitroprusside to a patient in kidney failure? Why?
No
CN accumulation. CN is eliminated by the kidneys
What metabolizes CN (cyanide)?
Sodium Thiosulfate
Drugs: Fenoldopam
Vasodilator
Dopamine-1 agonist
Works at the Dopamine-receptors at the renal bed
Continuous IV infusion
Tx: HTN emergencies , post-op HTN
