Kruse Part 2 Flashcards
Vasodilators include
- calcium channel blockers
- potassium channel openers
- dopamine agonist
- NO donors
Calcium channel blockers (CCBs) include
Dihydropyridines
non-dihydropyridines
Dihydropyridines include
amlodipine clevidipine felodipine isradipine nicardipine nifedipine nisoldipine
Non-dihydropyridines
diltiazem
verapamil
Potassium channel openers include
diazoxide
minoxidil
Dopamine agonists include
fenoldopam
NO donors include
hydralazine
nitroprusside
organic nitrates
Calcium channel blockers
-all CCBs bind to L-type Ca2+ channels
Non-dihydropyridine effects
-prominent cardiac effects, but also act at vascular tissues
verapamil>diltiazem
Dihydropyridines (DHPs) effects
- predominantly arteriolar vasodilation effects
- amlodipine, etc.
CCBs Adverse Effects and Toxicity
- generally very well tolerated
- excessive vasodilation–dizziness, hypotension, headache, flushing, nausea; diminished by long-acting formulations and long half-life agents
- constipation (especially verapamil), peripheral edema, coughing, wheezing, pulmonary edema
- use of verapamil/diltiazem with a beta blocker is contraindicated because of the potential for AV block
- verapamil/diltiazem should not be used in patients with ventricular dysfunction, SA or AV nodal conduction defects and systolic BP
CCBs clinical uses
- hypertension–most useful when combined with another agent to counteract the reflex cardiovascular responses
- hypertensive emergencies: parenteral formulations
- angina: reduction of O2 demand makes particularly useful
Potassium Channel Openers MOA
-increased potassium permeability stabilizes the smooth muscle cell membrane at resting potential, reducing the probability of contraction
K+ Channel Opener: Diazoxide
- arteriolar vasodilation
- diminishing use in hypertensive emergencies due to adverse effects: excessive hypotension can cause stroke and MI; hyperglycemia
K+ Channel Opener: Minoxidil
- arteriolar vasodilation
- clinical uses include severe hypertension and baldness
- adverse effects: headache, sweating, hypertrichosis, reflex tachycardia and edema–must be used with Beta blocker and diuretic to avoid these effects
Fenoldopam
- D1 receptor agonist
- renal afferent arteries contain dopamine receptors–activation increases blood flow to the kidneys
- for HTN emergencies and postoperative HTN
- adverse effects include tachycardia, headache, and flushing
- should be avoided inpatients with glaucoma due to increases in intraocular pressure
Hydralazine MOA
-release NO from endothelium–dilates arterioles, but not veins
Hydralazine Clinical Uses
Hydralazine Clinical Uses -first line oral therapy for hypertension in pregnancy, with methyldopa
- combination with nitrates is effective in patients with heart failure
- parenteral formulation useful in hypertensive emergencies
Hydralazine adverse effects
- can induce fluid and sodium retention
- headache, nausea, anorexia, sweating, flushing, palpitations
- reflex tachycardia can provoke angina in patients with ischemic heart disease
- lupus-like syndrome
Nitroprusside and organic nitrates uses
-used to treat hypertensive emergencies, heart failure, and angina (nitrates)
Nitroprusside and organic nitrate effects
- dilates both arterial and venous vessels–decreases TPR and venous return
- decreases both preload and afterload
- mainly relaxation of large veins–>decreased venous return–>decreased preload–>decreased O2 demand (major effect), smaller decrease in after load
Nitroprusside adverse effects
-excessive hyptension, cyanide poisoning
Nitrates adverse effects
-orthostatic hypotension, syncope, throbbing headache
Beta blocker use in hypertension
- no longer 1st line treatment for hypertension, except when concomitant with a compelling indication: heart failure, recent MI, reduced left ventricular function
- predispose ot diabetes, particularly when combined with thiazide
- relative contraindication in asthma
- less stroke protection than other antihypertensives
