Anti-Hypertensive Drugs Flashcards
What thiazide diuretics are used to treat hypertension?
- hydrochlorothiazide
2. metolazone
What are the loop diuretics used to treat hypertension?
- furosemide
2. torsemide
Whate are the K-sparing diuretics used to treat hypertension?
- triamterene
- amiloride
- spironolactone
What ACEI are used for hypertension?
- captopril
2. enalapril
What ARB is used for hypertension?
losartan
What renin inhibitor is used for hypertension?
aliskiren
What are the CCB used to treat hypertension?
Nifedipine (peripheral)
Verapamil (central)
Diltiazem (central)
What are the direct vasodilators used to treat hypertension?
- hydralazine
- minoxidil
- sodium nitroprusside
What 3 sympatholytics are uses to treat hypertension?
- metoprolol (BB)
- prazosin (a1 antagonist)
- clonidine (a2 agonist)
What diuretics work on the thick ascending limb?
Which work in the distal convoluted tubule?
Which work in the cortical collecting tubule?
TAL- loop diuretics (furosemide, torsemide)
DCT- thiazides (hydrochlorothiazide, metolazone
CCT- K-sparing (spironolactone, amiloride, triamterene)
Where is the majority of the Na load reabsorbed in the kidney?
What symporter reabsorbs it?
How much is absorbed in TAL, DCT, CCT?
TAL - 20 to 25% of filter Na gets reabsorbed by NaK2CL symporter
DCT - 5% is reabsorbed by NaCl symporter
CCT- 1-2% is reabsorbed by renal specific Na channels
Movement of water out of the lumen of the nephron into the interstitial space is due to the ________________. Water moves through both ___________ and through __________.
concentration of solutes in the interstitial space.
Water moves through:
- aqueous pores in luminal and basolateral membranes (transcellular)
- tight junctions between cells (paracellular)
Which diuretics are the most powerful? Why?
Loop diuretics that act on the NaK2Cl symporter are the most powerful because they work where MOST Na is absorbed.
(furosemide, torsemide)
Anything that increases Na delivery to the distal tubule will increase _______ excretion.
Explain why.
K+ because in the CCT there is a Na channel and a ROMK channel. If there is more Na going into the cell, more K will leave through ROMK
What is the mechanism of action of hydrochlorothiazide? What area of the kidney does it work on? What receptor?
It inhibits the NaCl symporter on the luminal membrane of the DCT to block reabsorption of Na and Cl.
If you have a woman has osteoporosis and hypertension what diuretic would you want to use?
thiazide because it absorbs Ca from the lumen while blocking Na absorption.
This decreases volume while saving Ca.
How do thiazides increase reabsorption of Ca?
The Na/K ATPase on the basolateral membrane makes a negative cell potential. This couples with the Na/Ca transporter on the basolateral membrane.
Thiazides block Na/Cl on the luminal membrane. Less Na goes in from the lumen, so more goes in from the Na/Ca pump. Bc Ca goes from the cell to the interstitium, more Ca gets pulled in from the lumen.
How do thiazides increase excretion of K and H?
They increase delivery of Na to the CCT.
Na goes in an Na specific channel and K leaves through a ROMK resultantly. This increases K excretion and can cause hypokalemia
What are the 3 major pharmacological effects of thiazide diuretics in terms of electrolytes?
- increased excretion of Na and Cl
- increased excretion of K and H
- decreased excretion of Ca WHEN GIVEN CHRONICALLY
How do thiazides enter the lumen of kidney? Why does this matter?
What drug do they interact with?
They enter the proximal tubule by organic acid transporters.
They interact with probenecid (gout drug)
A man has gout (on probenecid) and hypertension. What class of diuretic should you give him? Why?
K-sparing (spironolactone, amiloride, triamterene) because loop and thiazides enter the lumen via organic acid pumps so they interact with the probenecid.
What are the adverse effects of thiazides?
- volume depletion
- hypotension
- hyponatremia
- hypokalemia
- hypouricemia
- decrease glucose tolerance and unmask latent DM
What drugs interact with thiazide diuretics?
- probenecid
- digoxin
- Class III antiarrhythmics (k channel inhibitors)
What are the 2 main uses for thiazide diuretics?
- treat hypertension- well tolerated, inexpensive, used well alone and in combo
- edema associated with: CHF, liver disease (hepatic cirrhosis), renal disease (nephrotic syndrome, chronic renal failure, acute glomerulonephritis)
Most thiazides are ineffective with a GFR less than _____________ ml/min. This is because _________.
<30-40ml/min because most of the Na will have been reabsorbed before the DCT.
What is the mechanism of furosemide and torsemide? Where do they enter the kidney? Where in the kidney do they act? What receptor do they work on?
They are the loop diuretics that enter the proximal tubule of the kidney via an organic acid transporter and inhibit the NaK2Cl symporter in the TAL.
They also indirectly inhibit the reabsorption of Ca/Mg (paracellular)
How do loop diuretics decrease reabsorption of Ca and Mg?
They block NaK2Cl symporter. Because of this, there is less K+ going back into the lumen via ROMK and the lumen becomes less positive. This decreases the membrane potential difference from lumen to interstitial space.
Instead of 40/0 difference, it is a 10/0 difference. This will push less Ca and Mg back into the cell.
What are the pharmacological effects of loop diuretics in terms of electrolyte reabsorption and excretion?
- Na, Cl, K are excreted
- Ca and Mg are excreted
- K and H (in the CCT) are excreted
- Renin release
Why do loop diuretics stimulate renin release?
They decrease Na delivery to the macula densa–> renin release
They also cause reflex sympathetic stimulation due to volume depletion
What are pharmacokinetic considerations for loop diuretics?
- they enter kidney via organic acid pump so they have drug interactions (specifically probenecid)
- there is no slow release so they require frequent dosing (problems with compliance.
What are the adverse effects of loop diuretics?
- ototoxicity
- hyponatremia
- hypokalemia
- hyperuricemia
- hyperglycemia
What are the therapeutic uses of loop diuretics?
- acute pulmonary edema
- chronic congestive heart failure
- hypertension (not first choice)
- mobilize edema due to cardiac, renal, hepatic failure
What is the mechanism of action of triamterene and amiloride? How do they get into the lumen of the kidney? Where in the kidney do they act? What receptor?
They are K-sparing diuretics that enter the kidney through glomerular filtration. They act on principal cells of the cortical collecting duct but inhibiting Na specific channels. Decreased Na absorption reduces transcellular electrical potential (the lumen is less negative) so less K will leave through the ROMK.
This “less negative” lumen potential also reduces Ca and Mg excretion.
Why does increased delivery of Na to the CCD cause K excretion (and Ca and Mg excretion)?
The more Na that is delivered, the more substrate for the Na specific channel on the principal cell.
When Na goes into the cell, Cl is left in the lumen. This generates a - potential.
The negative potential draws K out of the cell through ROMK and Ca and Mg paracellularly.
What are the 3 main pharmacological effects of K-sparing diuretics (amiloride and triamterene)?
- minimal increase in Na secretion (most has been absorbed before the CCD)
- decreased K excretion
- Decreased Ca and Mg excretion
What can increase the toxicity of amiloride and triamterene?
Renal failure because these drugs are absorbed by glomerular filtration. Less filtration = increased drug concentration/decreased drug excretion which can enhance toxic effects.
Liver disease increases triamterene toxicity because the liver metabolizes triamterene.
What are adverse effects associated with amiloride and triamterene?
- hyperkalemia (contraindicated for renal failure, K+ supplements, ACEI, or other K sparing)
- drug interactions
What are the therapeutic uses of K-sparing diuretics?
- used in combo with other diuretics to reduce chance of hypokalemia and increase efficacy
- Triamterene is used for cystic fibrosis
What is the mechanism of action of spironolactone?
Where in the kidney does it act?
It acts on a mineralcorticoid receptor in the principal cells of the CCD to inhibit the actions of aldosterone (which normally absorb Na and excrete K)
What is the normal action of aldosterone?
It enters the principal cell and binds a mineralcorticoid receptor. This complex translocates to the nucleus and makes aldosterone induced proteins that upregulate Na-specific luminal channels and increase action of the Na/K ATPase.
Increased Na absorption creates a negative membrane potential which drives out K.