CVS: Anti-hypertensives Flashcards
Name a K+ channel blocker that can be used for hypertension.
Minoxidil
What is the MOA of minoxidil?
It is a K+ channel opener.
Opening of K+ channels, results in Ca2+ not being able to enter the cell and form a Ca++-calmodulin complex. MLCK not activated, so contraction of heart muscles cannot happen.
Works only to vasodilate arterioles NOT VEINS.
What kind of hypertension is minoxidil used to treat?
Severe to malignant HT.
Side effects of minoxidil include…
- Reflex sympathetic stimulation
2. Sodium and fluid retention
Name 4 ACE inhibitors.
Captopril
Enalapril
Ramipril
Lisinopril
What are ACE inhibitors used for?
- Hypertension
- Cardiac failure
- Post-MI
- Renal insufficiency
Adverse effects of ACE inhibitors include…
- Severe hypotension
- Acute renal failure
- HyperK
- Angioedema (due to increased bradykinin)
- Dry cough (due to increased bradykinin)
- Damage fetal renal system (so NOT for preg)
What is the MOA of ACE inhibitors?
Blocks ACE
Prevents formation of Angiotensin II =
- Lowers sympathetic activity
- Lowers Tubular NaCI resorption/K+ excretion and H2O retention
- Lowers aldosterone and ADH
- Lowers arteriolar vasoconstriction
- Inhibit bradykinin (releases NO and PG -> vasodilate) degradation
What are 2 contraindications for ACE-I?
- Pregnancy (teratogenic)
- Bilateral renal artery stenosis*
*To be sure, monitor for hyperK, and creatinine. If creatinine increases >30% -> likely renal artery stenosis
Name 6 ARBs (angiotensin II type 1 receptor blockers).
- Losartan
- Valsartan
- Candesartan
- Eprosartan
- Irbesartan
- Telmesartan
What is the MOA of ARBs?
Blocks angiotensin receptors. Similar effect as ACE-I but different mechanism.
ARB vs ACE-I?
ARB has no effects on bradykinin. It is more selective for angiotensin actions.
Therefore. will lead to less dry cough and angioedema.
Concerns for ARBs?
Prolonged inhibition of angiotensin II type ONE receptor will increase circulating angiotensin II -> increased angiotensin II type TWO receptor -> vasodilation.
Drug-drug interactions to take note of?
- If have asthma or diabetes, NO B BLOCKER
- If have CHF, NO CA2+ BLOCKER
- If pregnant, no ACE-I OR IRB.
What is the MOA of calcium channel blockers?
Block Ca channels predominantly in cardiac and smooth muscles -> same as K+ explanation
Concerns for calcium channel blockers?
Excessive cardiac depression: cardiac arrest, bradycardia, AV block, HF
Smooth muscle related: relaxation leading to flushing, dizziness, nausea, constipation, peripheral edema
Name 3 loop diuretics.
Sulfonamides: Furosemide, Bumetamide, Torsemide
Ethacrynic acid (if sulfur allergy)
What is the MOA of loop diuretics?
Selectively inhibit the luminal Na+/K+/2Cl- transporter in the thick ascending limb of Henle’s loop.
Will cause an increase in Mg2+ and Ca2+ excretion.
Reduce renal PG synthesis. NSAIDs interfere with this process by reducing PG synthesis more.
Furosemide increases renal blood flow.
Concerns for loop diuretics?
- Hypokalemic metabolic alkalosis
- Ototoxicity
- Hyperuricemia (gout due to hypovolemia assoc. w. enhanced resorption of uric acid)
- Hypomagnesemia
What is the MOA of aliskirin?
Inhibit renin. Taken orally with a short duration of action.
What is the MOA of alpha-1-blockers?
α1-Receptors mediate contraction and hypertrophic growth of smooth muscle cells
Hence it inhibits vascular smooth muscle contraction
When should alpha-1-blockers be taken?
Give at bed time for first dose, small dosing
First dose effect: marked postural hypotension
Name an alpha-1-blocker.
Prazosin
First line for DM + HTN?
ACEI
