For some time, doctors have known that a class of blood-pressure
medications, the ACE inhibitors, were effective at staving off diabetogenic
kidney failure (End Stage Renal Disease or ESRD). ACE inhibitors are quite
safe and inexpensive, but can produce a nuisance cough in a certain percentage
of users.
What are the alternatives? Are they as effective? Recent articles in the New England Journal of Medicine (2001, Vol. 345) discussed the Angiotensin-receptor antagonists, a new class of drugs shown to have similar effects to ACE inhibitors. Two of these drugs, irbesartan and losartan, were given to patients with type 2 diabetes and high blood pressure, who showed early signs of diabetic kidney disease. These individuals might otherwise have been placed on ACE inhibitors (others received a placebo). During the two-year period of the test, use of irbesartan reduced the number of individuals whose kidney disease progressed to a “critical stage” (as measured by proteinuria).
In another study, diabetics with advanced kidney disease received losartan
(50mg or 100mg daily), or a placebo, for a three-year period. Losartan significantly
reduced development of ESRD (in patients whose kidney complications were
much more serious than the first group). It also cut hospital admissions
for heart failure, but had no effect on the death rate.
In a third study, irbesartan was compared with the calcium
channel blocker amlodipine, and with a placebo, for a two-year period. As
above, there was a clear and demonstrable slowing in the development of
ESRD, but no reduction in mortality.
In all three tests, the demonstrated benefits (substantial delay in the
onset of significant kidney failure, ESRD) were clearly greater than blood
pressure control alone could explain. Need for dialysis or kidney transplant
was delayed an average of two years. The new drugs work much like the ACE
inhibitors, but do not produce the nuisance cough —but the ARAs are
far more expensive, and, the researchers note, they delay ESRD, they do
not cure it. “We still need more effective approaches,” writes
reviewer Robert W. Griffith, MD, “to prevent type 2 diabetes in the
first place.”