Antihypertensives Flashcards
Verapamil (what is it, what do we use it for)
Non-dihydropyridine (ie binds when L-type is open)
- Effects are greatest on contractility, blood flow, conduction
- Use for paroxysmal SVT
- Use for angina (dec in O2 demand, inc in coronary blood flow)
- Use for hypertension via reduction of SVR (still causes vasodilation, just not as much as dihydropyridines)
Verapamil side effect
Constipation
Diltiazem
Non-dihydropyridine
- Lowest incidence of side effects
- Effective in treating SVT
- Not a great antihypertensive drug (verapamil is stronger)
Nifedipine
Dihydropyridine (ie works on vasc SMCs and binds when channel is closed)
- Peripheral vasodilation (effective antihyperT, can use with beta blocker to prevent reflex tachy)
- ->has no direct effects on the myocardium or nodes, only the coronary arteries
Nifedipine contraindications
Post-MI, CHF
Nifedipine side effects
facial flushing, headaches, dizziness, palpitations, ankle swelling (think about MOA)
Important hemodynamic response to dihydropyridines in vascular SMCs
- Cause such profound peripheral vasodilation and limited myocardial effects that they can cause compensatory increase in HR and inotropy
- May produce reflex tachycardia and increase myocardial contractility
- Compensation increases myocardial workload and has been demonstrated to be detrimental in pts who are at high risk of having an MI
What is Hydralazine?
Direct arteriolar dilator (no effects on veins)
- preferentially effects, renal, peripheral, splanchnic and coronary arteries
- decrease in PVR leads to dec in BP
What is hydralazine toxicity?
- excessive vasodilation
- SLE-like syndrome that is reversible when drug is stopped (seen in females with >6mo treatment who are slow acetylators)
When do we use hydralazine?
- HyperT in pregnancy including preeclampsia
- In combo with beta antag to blunt reflex SNS activation
What is minoxidil
Direct arteriolar dilator (no effects on veins)
- MOA: Activates ATP-modulated K+ channels in arteries, allowing for hyperpolarization and relaxation
- Pharma actions: dec PVR=dec in BP
- Get reflex SNS activation–>RAAS activation–>BP comes back to baseline (give with beta blocker and diuretics)
Minoxidil side effect
Inc hair growth (hypertrichosis)
What is Na Nitroprusside?
Direct venous and arteriolar dilator
- MOA: SMCs metabolize it into NO–>cGMP–>SMC relaxation and vasodilation
- Leads to dec in afterload and inc in preload (ie venous return)
When do we use nitroprusside?
HyperT emergencies (rapid onset of 1-2 min and consistent response)
Easily titrated
initiate with beta blocker prior to discontinuing infusion
How do beta adrenergic antagonists work as antihypertensive drugs?
Reduce HR and renin release
