Vasodilators Flashcards
AT1 Receptors
- Angiotensin II binds to AT1 receptors
- Present on vascular smooth muscle and adrenal gland
- Stimulate constriction and aldosterone secretion, respectively
DRI
- EX: Aliskiren
- Direct Renin Inhibitor
- Competitively inhibits angiotensinogen from binding to renin
- Decreases Ang II synthesis
- Reduces vasoconstriction and aldosterone secretion
ACE-I
- Competitively inhibits ACE from converting Ang I to Ang II
- Reduces vasoconstriction and aldosterone secretion
- ALSO, inhibits degradation of bradykinin which increases vasodilation
ARBs
- Antagonists of AT1 receptors
- Reduces vasoconstriction and aldosterone secretion
DRI, ACE-I, and ARBsare used to treat….
Uncomplicated hypertension
Examples of ACE-Is
- Quinapril (Accupril)
- Benazepril (Lotensin)
- Enalapril (Vasotec)
- Ramipril (Altace)
- Lisinopril (Prinivil)
- Fosinopril (Monopril)
Examples of ARBs
- Olmesartan (Benicar)
- Irbesartan (Avapro)
- Valsartan (Diovan)
- Losartan (Cozaar)
- Candesartan (Atacand)
1st Line therapy for CKD/Type II DM
ACE-I and ARBs
ACE-Is + Hepatic Excretion
- Benazepril (Lotensin)
- Ramipril (Altace)
- Fosinopril (Monopril)
- Trandolapril
Preferred for those with CKD
RAS-I SE
- Hyperkalemia (K > 5 mEq/L) - from reduced aldosterone synthesis
- Mild Elevation of Serum Creatinine - dilation of flomerular efferent arteriole, reduces filtration pressure and thus GFR
- *30% increase in SCr -= acceptable**
RAS-I + Pregnancy
- DO NOT USE
- D/C if preggo or planning on becoming preggo
ACE-I SE
- Dry cough - develops in about 1-10% of patients, believed to be due to increased bradykinin
- Angioedema - NOT an allergic response, also due to increased bradykinin (Can be fatal, is rare, most common with ACE-I)
24-H BP Goal
- Trough/Peak > 50%
- Want to meet this above criteria when picking ACE-I or ARB for once a day use
- Allows for less exaggerated peak response
- More uniform 24 hour control
ACE-I not good for 24-H Use
- QUinapril (50%)
- Benazepril (50%)
- Enalapril (50%)
- Captopril (25%)
QuBEC
CCBs
- Stop the efflux of Ca which activates vasoconstrictors
- By blocking these influxes you block their downstream vasoconstrictive actions
Dihydropyridine
- Type of CCB
- Blocks calcium efflux in arterioles
- Reduces PVR by dilating arterioles
- “dipine”
Non-dihydropyridines
- Type of CCB
- Blocks calcium efflux in SA node and ventricular cardiac myocytes
- Slow HR
- Reduce cardiac contractile force
EX: Verapamil, Diltiazem
CCBs used to treat…
Uncomplicated HTN
CCB SE
- ALL: hypotension, flushing, dizziness
- Dihydropyridine: peripheral edema (from dilation of arterioles increasing capillary pressure and drawing fluid out)
- Non-dihydropyridine: bradycardia
CCBs + Preggo
- Limited clinical evidence
- Nifedipine is one of the three agents okay to use
Other Antihypertensives for Preggo
- Methyldopa
- Labetalol
Minoxidil
-Activate K+ efflux directly
-Prevent Ca+2 channel opening
-Target: Arterioles
-Use: Resistant HTN
SE: Fluid rentention (+diuretic) and Tachycardia (+B-blocker)
Hydralazine
- Activate K+ efflux directly
- Prevent Ca+2 channel opening
- Target: Arterioles
- Uses: Resistant HTN (oral), HTN crisis (IV), preeclampsia, eclampsia
- SE: tachycardia
- CI: CAD
Nitroprusside
- Metabolized to release NO
- Target: arteries and veins
- Use: HTN Crisis (IV)
- SE: Cyanide toxicity
Nitroglycerin
- Metabolized to release NO
- Target: arteries and veins
- Use: HTN Crisis (IV)
- SE: Headache, tachycardia
Fenoldopam
- Activate dopamine receptor D1 and K+ efflux
- Target: Arterioles
- Use: HTN Crisis (IV)
- SE: Headache and nausea
