Why do we still use furosemide as our first line loop diuretic?

We currently have 3 loop diuretic options – furosemide (Lasix), bumetanide (Bumex) and torsamide (Demadex).  They are all currently generic and available for 50 cents or less per pill. In the 70s, during my residency I believe furosemide was already generic.  The remaining two loop diuretics became available after my residency and thus had higher prices for several years. Here is the problem.  Furosemide is inconsistently absorbed across people and averages only 50% but for some people absorption is even less.  Bumetanide and torsamide get absorbed consistently and close to 95%. Several times this month we had patients admitted for increased edema.  They all responded well to IV furosemide, but when we gave a test dose of oral furosemide, they had a minimal response.  We then tried bumetanide (approximate conversion is 1 mg equivalent to 40 mg of furosemide).  Each time oral bumetanide produced an excellent diuresis. Bumetanide and torsamide have superior absorption.  A careful comparison would give us not good reason to continue using furosemide as our first choice loop diuretic. So I ask again, why is furosemide first line?  Maybe a nephrologist or cardiologist can help me here.  I really do not understand.
Source: DB's Medical Rants - Category: Internal Medicine Authors: Tags: Medical Rants Source Type: blogs