First Pass Miss Exam 2 Flashcards
Why is furosemide good for hypercalcemia? What drug should be used for hypocalcemia?
Blockage of NKCC prevents K+ from making lumen most positive charged, inhibiting calcium reabsorption.
For hypocalcemia, blocking NCC via HCTZ will facilitate reabsorption of calcium
Why is furosemide good in acute renal failure and hyperkalemia?
Increases renal blood flow and hence urine flow, which can flush out K+ (via principle cells) as well as intratubular casts
What is amiloride used for?
Prevention of diuretic induced hypokalemic acidosis
-> also prevents entry of lithium into principal cells (blocks ENaC), limiting aquaporin-2 interference in nephrogenic diabetes inspidus
What is spironolactone used for and why?
- severe CHF -> aldosterone mediates myocardial fibrosis, and spironolactone antagonizes this effect of cardiac remodelling
- Primary and secondary aldosteronism
- Hypertension with loop / thiazide diuretics to reduce K+ loss
- hepatic cirrhosis -> reduces edema
What are the two PCSK9 inhibitors and who uses them? How do they work?
- Alirocumab
- Evolucumab
= EVIL-LAIR
Used as a second line to statins when LDL remains high or statin side effects are high, but very expensive.
Increases the expression of LDL-R on liver by monoclonally binding PCSK9
What drug commonly increases plasma levels of statins and what can be taken instead?
Gemfibrizol, a fibrate to lower triglycerides
Can take fenofibrate instead
What are the statins metabolized via CYP3A4 and what drugs can make this a problem?
Simvastatin, lovastatin, and atorvastatin
Macrolides, azole antifungals, and HIV protease inhibitors may decrease their metabolize and increase risk of myopathy / rhabdomyolysis
What is the high vs low total cholesterol range?
Low / desirable: <200 mg/dL
High: >240 mg/dL
LDL: <100, high>160
HDL: <40, high >60
What is the mechanism of action of niacin?
Binds to and activates GPCR in adipose tissue, decreasing release of free fatty acids from stored triglycerides, reducing need for VLDL packaging by liver, and reduction in LDL.
HDL is increased by improved stability of Apoprotein A1
What is the effect of AT2 on the kidney?
Directly stimulates Na/H exchanger in proximal tubule, enhances aldosterone secretion, and increased GFR while decreasing RBF by constricting the efferent arteriole
What is the effect of AT2 on cardiac / vascular remodelling?
Stimulates the migration, proliferation, and hypertrophy of vascular smooth muscle cells, as well as hypertrophy of cardiac myocytes. Promotes myocardial fibrosis through aldosterone.
Also increases preload (volume expansion) and afterload (greater peripheral resistance)
Why are ACE inhibitors important in chronic heart failure? What effect does this have on cardiac output and stroke volume?
Reduce preload and afterload, thus slowing the progress of ventricular dilation
This actually increases cardiac output and stroke volume in CHF
Give two important side effects of ACE inhibitors?
- Persistant dry cough
- Hyperkalemia (due to decreased aldosterone secretion) -> especially a problem in renal failure or if patient is on another K+ sparing diuretic -> raised banana dacquiri
When are ACE inhibitors contraindicated?
Pregnant patients -> teratogenic
Give two angiotensin receptor (AT1) blockers: ARBs?
- Losartan
2. Valsartan
What is the neprilysin inhibitor and how does this work? Who is it used in?
Sacubitril
-> think of it inserting a cube into the neprilysin rather than a stick
Inhibits neprilysin, which is responsible for cleavage of natriuretic peptides which have good effects.
Used in combination with valsartan for treatment of heart failure
How do beta blockers reduce oxygen consumption by the heart?
They reduce the heart rate, allowing for increased filling time and stroke volume
Furthermore, they reduce the inotropy of the heart, resulting in less forceful contractions
What are the dihydropyridines of significance?
- Nefedipine - avoid in MI due to reflex tachycardia
- Amlodipine - longer halflife, no reflex tachycardia
-> reduces mortality in LV dysfunction
think the ‘dipin’ station for ice cream in sketchy
What are the non-dihydropyridine calcium channel blockers?
- Verapamil - Also has alpha 1 antagonist activity -> hypotension. It should not be used in heart failure but decreases digoxin’s clearance.
- Diltiazem
-> very vanilla and delicious dark chocolate ice cream
What is the mechanism of action of the non-dihydropyridine VGCC blockers?
They bind to the L type Calcium channel, but are cardioselective and will bind to both the open and inactivated form.
They reduce inward calcium current and delay channel closing, reducing the chronotropy and inotropy of the heart. -> contraindicated in AV block or with beta blockers due to excessive bradycardia
There is only minor blockage of L-type calcium channel on arteries
What are non-dihydropyridines used to treat and why?
Angina -> reduce cardiac work by reduction of inotropism
Supraventricular tachycardias -> delayed AV node conduction
Antiarrhythmia in general -> DO NOT USE IN HEART FAILURE DUE TO DECREASED INOTROPY
What drugs decrease cardiac remodeling?
Beta blockers (especially carvediol), ACE inhibitors / ARBs (through lack of aldosterone), spironolactone
What is the I-funny channel blocker and how does it work?
Ivabradine -> main use is reduction in tachycardia in people already on beta blockers
Blocks the channel in pacemaker cells, especially the SA node which is activated by hyperpolarization, and leads the pacemaker cells to spontaneously depolarize and allow calcium inside
If channel is a nonspecific channel (lets Na+ and K+ flow)
What is the mechanism of action of dihydropyridines?
They bind the L type Calcium channel in its open state, slowing calcium entry when it’s open, but not delaying its closure.
Dihydropyridines are vasoselective (rather than cardioselective), and prevent vascular smooth muscle contraction -> do not affect preload due to only arterial action