Flashcards in Antihypertensive Deck (69)
What do calcium channel blockers do?
Selectively inhibit Ca++ ions at L type Ca channnels
Reduce myocardial O2 demand by decreasing afterload and coronary vasodilation
Also decrease HR
What are the pharmacologic effect of Ca++ channel blockers?
↓ Heart Rate
↓ SA Node Activity
↓ AV Node Conduction
↓ Systemic BP
-2º vascular smooth muscle relaxation
What are clinical effects of calcium channel blockers?
Depression of myocardial contractility
Improving myocardial ischemia
-Verapamil at the AV node(slows conduction)
-Significant for anti-arrythmic effects
What are the clinical uses of calcium channel blockers?
Coronary artery spasm
What are verapamil's effects?
Derivative of papavarine
*AV node depression*
Also works on fast sodium channel (potentiates local)
What are the clinical uses of verapamil?
Maternal and fetal tachydysrhythmias ( will cross placenta)
Intra-arterial injection for cerebral vasospasm
What are the effects of nifedipine?
negligible SA/AV node effects
NO Myocardial depression
What are the clinical uses of nifedipine?
What effects does nifedipine have on conduction?
No effects on either
NIfedipine is sensitive to light. T/F
Nifedipine has been associated with peripheral _______.
Which calcium channel blocker causes the most vasodilation (especially on coronary arteries)?
What are teh clinical uses of nicardipine?
Improves LV function during ishemia
What is halflife of nicardipine?
What is different about nimodipine compared to nifedipine? what is it used to treat?
Lipid soluble so it will cross BBB
used to treat cerebral vasospam
What is bolus and infusion dose of nicardipine?
What are the effects of diltiazem?
Slows AV node function--antiarrhythmic
minimal myocardial depression
What are the clinical uses of diltiazem?
SVT including afib and flutter
Used similar to verapamil
What drugs do calcium channel blockers interact with?
K containing solution
Digoxin ( may increase plasma concentration)
What class is clevidipine?
it is the first third generation dihydropyridine
HOw is clevidipine cleared?
what is the halflife of clevidipine?
What is the effect of clevidipine?
Arterial specific vasodilating effects
What are the peripheral vasodilators?
Sodium Nitroprusside (SNP)
When should you give a peripheral vasodilator?
Treat HTN crisis
Maintain controlled hypotension
Improve LV stroke volume
How do nitrovasodilators work?
Increase NO production which leads to increased cGMP
What are the functions of NO
Maintains CV tone, platelet aggregation, and CNS signalling
Aids in GI relaxation and immune functions
how is NO inactivated?
What is the duration of NO?
NO is synthesized from ___________
Which generates more NO, arteries or veins?
HOw are each of the following related to NO:
Vasospasm (after SAH)
Essential HTN: decrease in NO production
Septic shock: surge in NO
Atherosclerosis: decrease in NO leading to an increase in platelet production
Vasospasm: decrease in NO
How is NO used clinically?
to tx pulmonary HTN
heart and lung transplant
-20-40 ppm; FGF must be > than MV
Does sodium nitroprusside (SNP) work on arterial or venous?
decereases both preload and afterload
How does the chemical struture of SNP relate to its toxicity?
Iron center with 5 CN and 1 NO hanging off
What is the infusion dose of SNP. Where do you start to run into trouble
CN accumulation at >2mcg/kg/min
What is the duration of SNP?
At low doses SNP causes a greater decrease in ________ than ________
SNP does not cause pulmonary vasodilation. t/f
What are negative effects of SNP?
-cyanide, thiocyanate, Methemoglobinemia
Ischemia in HTN pts
Risk of increase ICP
Inhibits platelet function
N/V (from hypotension)
What is the treatment for cyanide toxicity
1. Turn off SNP
2. increase O2
3. Bicarb if acidotic
What are the effects of cyanide toxicity?
What are the symptoms of thiocyanate toxicity?
Why would thiocyanate toxicity occur?
impaired renal clearance
What is the tx for thiocyanate toxicity?
When would you use SNP?
-Decrease LV afterload
-manipulate BP during cross clamp
SNP inhibits hypoxic pulmonary vasoconstriction. T/F
With SNP cerebral blood flow is ________ and platelet aggregation is _________.
What is a side effect of NTG?
Nitroglycerin only dilates veins. T/F
F. if enough is given it will dilater arteries as well
How does NTG decrease ventricular wall tension?
less volume returns
What are the routes of administration for NTG?
Sublingual, transdermal. IV
Not PO--takes too long and too much 1st pass metabolism
What is the emlimination half time of NTG?
what effects does NTG have on the Pulmonary system?
What are the clinical uses of NTG?
Hydralizine is principally a _______ vasodilator
What is the onset/duration of hydralazine?
onset 15-20 minutes, IV dose lasts hours
What is the dose for hydralizine?
2.5-5 mg q 15 minutes
What are the side effects fo hydralazine?
Rash (when on hydralazine chronically)
Why might hydralazine be preferred in OB
Maintains uterine BF
Who would use papavarine?
Mostly vascular surgeons
you can give phenylephrine or norepi to fix it if it causes to much hypotension
What are the uses of adenosine?
potent coronary vasodilator
0.6-1.5 sec half life
use for PSVT
What is trimethaphan?
How do ace inhibitors work?
Block conversion of Ang I → Ang II
Prevent Ang II vasocontriction and stimulation of sympathetic system
Ang II responsible for secretion of aldosterone
What is the advantage to ACE inhibitors?
No CNS effects like other drugs
What are the side effects of ACE inhibitors?
Contraindicated for pts with renal artery stenosis
What is the protocol for ACE inhibotors and surgery?
Continue normal regimen up to surgery and being again ASAP
Pt on chronic ACE inhibitor may exhibit exaggerated HYPOtension with GA
(there is some new evidence suggesting that withholding drugs for 12 hrs preop will decrease)
Hypotension normally responds to fluid or pressor therapy
What type of drug is losartan?