Pharm Test 3 Flashcards
in general, diuretics decrease bp by
decreasing blood volume by increasing urinary volume
why is carbonic anhydrase not recommended as a front line diuretic?
because of it’s toxicity: decreases K+ and lowering the body pH by wasting HCO3
where does mannitol work?
throughout the entire nephron but primarily in the proximal convoluted tubule
mannitol contributes to the _______ of the urine
osmolality
what kind of diuretic is mannitol?
osmotic
what is an osmotic diuretic?
A drug that is going to affect the osmolality of the fluid that’s in the nephron.
what is osmolality?
the number of dissolved particles that are in a solution.
what is a normal body osmolality?
300mOsm/kg
what is the osmolality of the renal cortex?
300 mOsm/kg
what is the osmolality of the kidney as we descend into the renal medulla?
It increases as high as 1200mOsm/kg
why is the osmolality so high in the renal medulla?
as we’re reabsorbing the sodium, before it gets into the blood stream, it goes into the medulla first.
what is an impermeable solute?
a solute that cannot be reabsorbed from the nephron back into the blood.
how does mannitol work?
It is a sugar alcohol that increases the osmolality of the inside of the nephron. Since it’s more concentrated in the nephron water stays in the nephron and goes into the medulla to be excreted.
what is the s2 segment of the nephron?
The fairly straight portion of the proximal tubule before it reaches the loop of Henle. It has special transporters that can transport much larger substances into the urine.
why don’t we have water leaving in the ascending portion of the loop of Henle? what kind of transport do we have instead?
because this section is water impermeable
Na+ leaving via the NKCC2 pump in order to balance the osmolality in the nephron.
what kind of ion movement happens in the thick ascending limb of the loop of Henle?
NKCC2 pumps Na+, K+ and 2 Cl- INTO the Thick Ascending Limb
K+ leak channels leak K+ OUT of the thick ascending limb into urine
this positive efflux pushes
Ca++ and Mg++ INTO the Thick ascending limb
Na+/K+ ATPase pumping Na+ OUT of the Thick ascending limb
K+Cl- cotransports both OUT of the Thick ascending limb into the interstitium.
which part of the loop of Henle is permeable to water? Which direction does water go?
the descending portion
water leaves the nephron to try and balance out the really high osmolality in the renal medulla
what is moving in/out of the collecting tubule?
water leaves
where do loop diuretics work? How?
the thick ascending limb. It blocks the NKCC2 pump so more sodium stays in the urine. water follows.
which electrolytes get depleted or less absorbed when using loop diuretics?
Na+
K+
Cl-
Mg++
Ca++
what is the difference between loop diuretics and carbonic anhydrase inhibitors?
Loop diuretics don’t effect bicarb
what is toxicity of loop diuretics?
allergic reactions. Loop diuretics are Sulfonamides.
what is the only loop diuretic that is not a sulfonamide?
Ethacrynic Acid
why is there less water movement in the distal convoluted tubule?
because the osmolality in the renal cortex is closer to 300mOsm/kg which is balanced
What kind of electrolyte movement can we expect in the distal convoluted tubule?
Na+ and Cl- going INTO the Distal Convoluted Tubule
Ca++ leak channels INTO the DCT thanks to parathyroid hormone
Na+/K+ ATPase pumping sodium OUT of the DCT
NCX pumping Na+ IN and Ca++ OUT of the DCT
Ca+/H ATPase pumping Ca++ OUT and H+ INTO the DCT
what do thiazide diuretics target?
the NCC
Na+ and Cl- co transport into the DCT
it also gets rid of a little bit of bicarb
what is the prototype thiazide drug?
hydrochlorothiazide
which diuretics are sulfonamides?
loop and thiazides
thiazides don’t work as well as _____
loop diuretics
When combining diuretics, you want to combine what types?
drugs that work on different parts of the nephron.
where is the final site in the kidney that sodium can be reabsorbed?
the collecting tubule
where in the kidney is the most important site for K+ secretion?
the collecting tubule
where is aldosterone released from?
the adrenal cortex
we have sodium reabsorption in the collecting tubule d/t
aldosterone being released in response to low bp. aldosterone binds to the receptor inside the collecting tubule and increases the activity of ENaC
what is ENaC?
a sodium transporter pulling sodium out of the urine and into the collecting tubule
what are the principal cells responsive to in the collecting duct of the kidney?
aldosterone
what is the normal without drugs movement of Cl-, Na+, and K+ in the collecting tubule?
More Na+ moves into the Collecting Tubule than K+ leaves the CT. This makes the urine net negative which drives Cl- through the cells to the interstitium
what is the movement of Cl-, Na+, and K+ in the collecting tubule when you give potassium wasting diuretics with affects on sodium?
Cl- moves through the cells to the interstitium
LOTS of Na+ moves into the Collecting Tubule (because it was blocked from being absorbed higher up)
LOTS of K+ leaves the CT (to balance out Na+)
what is the movement of HCO3-, Na+, and K+ in the collecting tubule when you give potassium wasting diuretics with affects on bicarb? (acetazolamide)
Bicarb can’t move between the cells so this makes the urine extra negative
LOTS and LOTS of Na+ moves into the Collecting Tubule (because it was blocked from being absorbed higher up)
LOTS and LOTS of K+ leaves the CT (to balance out Na+)
what drug antagonizes aldosterone in the kidney?
Spironolactone
why is spironolactone K sparing?
because you block aldosterone in the collecting tubule. This blocks Na+ reabsorption which makes the urine more Positive so K+ stays within the collecting tubule.
what drug is similar to Spironolactone and how does it work?
Amiloride
it blocks the ENaC pump
what is Conn’s syndrome?
an increase in aldosterone production d/t a tumor or hyperplasia. this works as a diuretic
would use a K+ sparing diuretic
what is a contraindication to taking a K+ sparing diuretic?
pt is taking K+ supplements
toxicity of K+ sparing drugs
hyperkalemia
what is the antidiuretic hormone in the collecting duct?
vasopressin
what does vasopressin do in the kidneys?
increases cAMP which moves aquaporin channels to the cell wall so that water can rush into the collecting duct and then the interstitium.
why would a patient not produce ADH?
possibly d/t their blood pressure being too high already
what drug blocks the receptor for ADH?
Conivaptan a K+ sparing diuretic
What is Mannitol normally used for?
to decrease ICP
to promote removal of renal toxins
Describe 2 drugs that reduce potassium loss during sodium diuresis.
Potassium sparing diuretics:
Block aldosterone receptors (spironolactone)
Inhibition of sodium flux through ion channels in luminal membrane (amiloride)
List the potential side effects of mannitol
Extracellular volume expansion d/t rapidly distributed fluids to extracellular compartments. This can lead to congestion and hyponatremia prior to diuresis.
Dehydration
Hypernatremia
Hyperkalemia
In patients with renal failure - hyponatremia
What is the major application for acetazolamide?
Used in acute mountain sickness because blocks carbonic anhydrase in CNS
What is the major application for thiazides?
diuretic when K+ needs to be preserved
What is the major application for loop diuretics?
Most efficacious diuretic, used for fluid overload, especially when K+ wasting is okay
What is the major application for potassium sparing diuretics?
Useful in patients with hypokalemia
Most useful in states of mineralocorticoid excess (result in overproduction of aldosterone)
Primary - over produce aldosterone
Conn’s syndrome
Pituitary gland tumor
Results in Ectopic ACTH production
Secondary
CHF
Nephrotic syndrome
Use of other diuretics that waste potassium
What are the toxicities associated with acetazolamide?
K+ depletion
Acidosis
What are the toxicities associated with thiazides?
allergic reaction.
sulfonamide
What are the toxicities associated with loop diuretics?
allergic reaction.
sulfonamide
What are the toxicities associated with potassium sparing diuretics?
Hyperkalemia
What is diabetes insipidus?
insufficient ADH which leads to excessive thirst and urination.
What is one of the treatments for neurogenic Diabetes insipidus?
Thiazide diuretics.
It depletes the patient further and leads to decreased urinary output overall.
what are the symptoms of asthma?
wheezing, breathlessness, chest tightness, coughing, and symptoms increased at night and early morning
what are the factors involved in asthma?
- Airway inflammation causing obstruction
- Increased responsiveness of trachea and bronchi to various stimuli
- Widespread narrowing of airways
- Contraction of airway smooth muscle
- Mucosal thickening
edema, cellular infiltration - Mucous plugs
- Involves WBC’s and epithelial cells
- Reversible