44 Questions
Why is diuresis scanty in the distal tubule?
Most Na has already been reabsorbed before reaching the distal tubule.
What is the mechanism of action of Triamterene/Dyrenium?
It disrupts Na-K exchange in the distal nephron by direct inhibition.
What is the effect of Triamterene/Dyrenium on Na excretion?
It increases Na excretion.
What is the effect of Triamterene/Dyrenium on K secretion?
It reduces K secretion.
What is the primary effect of Triamterene/Dyrenium on K levels?
It conserves K.
What is Triamterene/Dyrenium classified as?
Non-aldosterone antagonist.
What is the extent of diuresis caused by Triamterene/Dyrenium?
Minimal diuresis.
Where does Triamterene/Dyrenium act to disrupt Na-K exchange?
Distal tubule.
What is the primary benefit of using nifedipine over verapamil in patients with certain disorders?
It is less likely to exacerbate AV block, heart failure, bradycardia, or sick sinus syndrome
What is the primary mechanism of action of hydralazine?
Dilation of arterioles, reducing peripheral resistance
What is a contraindication for the use of hydralazine?
Coronary artery disease
What is the effect of aldosterone on the distal nephron?
It stimulates the synthesis of pumps responsible for sodium and potassium transport.
Where does furosemide act in the nephron?
In the thick segment of the ascending limb of the loop of Henle
What is the benefit of combining hydralazine with a beta blocker?
Preventing reflex tachycardia
What is a potential risk of using hydralazine in older adults?
High risk for falls due to polypharmacy and orthostatic hypotension
What is the effect of furosemide on renal blood flow and GFR?
It has no effect on renal blood flow and GFR
What is the benefit of using nifedipine in patients with heart failure?
Reducing the risk of overt heart failure
What is the MOA of hydrochlorothiazide?
It promotes urine production by blocking reabsorption of Na and Cl in the early segment of the distal convoluted tubule
What is the effect of spironolactone on sodium excretion?
It decreases sodium excretion
What is the recommended patient education for those taking nifedipine or hydralazine?
Recording anginal episodes, blood pressure, and adverse effects
What is the current status of hydralazine in antihypertensive therapy?
It has been replaced by newer antihypertensive medications
What is the effect of spironolactone on potassium levels?
It increases potassium levels
Where does spironolactone act in the nephron?
In the distal nephron
What is the MOA of spironolactone?
It blocks the action of aldosterone in the distal nephron
What is the effect of furosemide on water reabsorption?
It decreases water reabsorption
What is the effect of hydrochlorothiazide on urine production?
It increases urine production
What is a necessary consideration before starting a specific medication?
Cardiac function and kidney function
What is the primary purpose of the medication discussed?
To manage chronic angina
What is a potential effect of the medication on the heart?
Increased QT wave duration
What is not a purpose of the medication discussed?
To treat acute angina
What should be evaluated before starting the medication?
Renal function and cardiac function
What is a condition that the medication does not treat?
Acute angina
What is a relevant aspect of the medication's effects?
Its impact on the QT wave
What is a separate condition mentioned in the context?
Vitamin B12 deficiency
What is the primary effect of Triamterene/Dyrenium on the distal tubule?
Inhibition of Na reabsorption
What is the consequence of Triamterene/Dyrenium's action on Na-K exchange?
Increased Na excretion and decreased K excretion
What is the mechanism of Triamterene/Dyrenium's action on the kidney?
Inhibition of the Na-K pump
What is the effect of Triamterene/Dyrenium on blood pressure?
Decrease in blood pressure
What is the classification of Triamterene/Dyrenium?
Potassium-sparing diuretic
What is the effect of Triamterene/Dyrenium on the heart?
Decrease in cardiac workload
What is the primary site of action of Triamterene/Dyrenium?
Distal tubule
What is the consequence of Triamterene/Dyrenium's inhibition of Na-K exchange?
Decreased Na reabsorption and decreased K secretion
What is the effect of Triamterene/Dyrenium on potassium levels?
Increase in potassium levels
What is the therapeutic use of Triamterene/Dyrenium?
Treatment of hypertension
Study Notes
Aldosterone and Diuretics
- Aldosterone promotes sodium-potassium exchange by stimulating cells of the distal nephron to synthesize more pumps responsible for sodium and potassium transport.
- Furosemide (Loop diuretic) MOA:
- Acts in the thick segment of the ascending limb of the loop of Henle
- Blocks reabsorption of Na and Cl
- Prevents reabsorption of water, leading to profound diuresis even when renal blood flow and GFR are low
- Hydrochlorothiazide (Thiazide diuretic) MOA:
- Steroid derivative
- Promotes urine production by blocking reabsorption of Na and Cl in the early segment of the distal convoluted tubule
- Increases flow of urine
- Spironolactone (Aldosterone Antagonist, potassium-sparing diuretic) MOA:
- Blocks the action of aldosterone in the distal nephron
- Leads to retention of K and excretion of Na
- Diuresis is scanty because most Na has already been reabsorbed before reaching the distal tubule
- Triamterene (Non-aldosterone antagonist, potassium-sparing diuretic) MOA:
- Disrupts Na-K exchange in the distal nephron by direct inhibition
- Decreases Na reabsorption and reduces K secretion, leading to increased Na excretion and K conservation
- Minimal diuresis
Hydralazine
- MOA: Dilates arterioles, decreasing peripheral resistance and lowering arterial BP
- Use: HTN crisis, HF (reduces afterload for a short time in CHF)
- Can be used in infants 1 month
- Was common in the past, now replaced by newer anti-HTN meds
- Requires combination with BB to prevent reflex tachycardia
- CI: CAD, angina attacks
- High risk for falls in older adults (polypharmacy and orthostatic hypotension)
Nifedipine
- Use: Long-term use reduces rates of overt heart failure, coronary angiography, and coronary bypass surgery
- No effect on rates of stroke, myocardial infarction, or death
- Preferred over verapamil for patients with AV block, heart failure, bradycardia, or sick sinus syndrome
- Pt education: Record anginal episodes, BP, AE
Pathophysiology of HF
- Review patho and stages of HF (4 stages)
This quiz covers the function of the nephron, including the role of aldosterone in sodium and potassium transport, and the mechanism of action of furosemide, a loop diuretic.
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