Telmisartan Offers Better Renoprotection
CHICAGO—Telmisartan (Micardis HCT), a novel angiotensin receptor blocker (ARB), and the older ARB losartan have similar BP-lowering efficacy in hypertensive patients with diabetic nephropathy, but treatment with the new agent is associated with larger reductions in proteinuria, new findings show.
“Our data suggest that at similar levels of blood pressure control, telmisartan may confer greater protection against progression to end-stage renal disease (ESRD),” George Bakris, MD, professor of medicine and director of the hypertension center at the University of Chicago Hospitals, said here at the 22nd Annual Scientific Meeting of the American Society of Hypertension.
Renal outcome trials have demonstrated that using renin-angiotensin system (RAS) blockade to control BP is essential for decreasing renal disease progression in diabetes, Dr. Bakris observed. In these clinical trials, a proteinuria reduction larger than 30% at six months to one year strongly correlated with slowed progression of diabetic nephropathy and decreased cardiovascular events.
The new trial was undertaken to determine whether pharmacologic differences between telmisartan and losartan would produce larger and more durable reductions in urinary protein excretion over time in hypertensive patients with type 2 diabetes and overt nephropathy.
Losartan has been approved by the FDA for slowing diabetic nephropathy progression. Investigators randomized 860 patients to two weeks of treatment with either telmisartan 40 mg or losartan 50 mg after a four-week run-in period, and then titrated to 50 weeks of treatment with telmisartan 80 mg or losartan 100 mg. The primary outcome measure was the change from baseline in morning spot urinary protein:creatinine (mg/gCr).
Results from 687 patients in the trial showed the mean final urinary protein creatinine ratio after one year of treatment was 0.71 in the telmisartan group and 0.80 in the losartan group, for a reduction from baseline of 29% and 20% for the two groups, respectively.
The larger antiproteinuric effect of telmisartan cannot be ascribed to differences in BP control because BP reductions were comparable in the two groups (4.8/3.2 mm Hg decrease in the telmisartan group and 2.7/2.9 mm Hg decrease in the losartan group), Dr. Bakris reported.
The differences in effect could relate to pharmacologic factors such as lipophilicity, magnitude of receptor binding, and duration of action, he added.