Category Archives: Diuretics

Loop Diuretics: Someone Build Me an Ark…

…’cause there’s gonna be a FLOOD!

As you may have guessed, loop diuretics REALLY do their job.  Actually, they tend to do their job a little too well, so they are used only when other attempts have failed or in dire cases.

Their main target is the thick ascending Loop of Henle.  I think that sounds kind of gross, so let’s just call it the ascending loop.  If you remember anything about this target, remember reabsorption.  Loop diuretics inhibit the reabsorption (so promote the excretion) of sodium, potassium, calcium, magnesium, and good old H2O.  Look at all of those precious ions being excreted!!

The prototype for loop diuretics is furosemide (Lasix).  I remember this by thinking how furiously furosemide kicks out all of those cute little ions.

What are the therapeutic effects of furosemide?  Well…

1.  Effectively and quickly lowers blood pressure by reducing blood volume

2.  Gets rid of excess fluid in interstitial spaces

And the adverse effects should be rather easy to guess…

1.  Hypokalemia (this is a big one, and really the main problem with loop diuretics)

2.  Dehydration

3. Hypotension

There are other pros and cons, but these are the main ones.  The most common use for furosemide and other loop diuretics is in heart failure, and you will often see them used in conjunction with another cool drug called digoxin!