CHICAGO — Telmisartan provides greater reduction in proteinuria than losartan does after 1 year of treatment in patients with hypertension and diabetic nephropathy, Dr. George Bakris said at the annual meeting of the American Society of Hypertension.
This difference can't be attributed to differences in BP control, because BP reductions were comparable in patients taking either angiotension II receptor blocker (ARB), Dr. Bakris, who is lead investigator of the AMADEO study, said in a press briefing.
After stopping the drugs for 2 months, as per protocol, about twice as many patients on telmisartan were reported to have experienced a slightly greater antiproteinuric effect than did those on losartan. This is important to clinicians, because it suggests that telmisartan has done something independent of controlling BP to change the natural history or biology of the disease. “The differences between these ARBs in terms of receptor binding, lipophilicity, and duration of action may be responsible for the differences in the effects that you see,” said Dr. Bakris, director of the hypertension unit at the University of Chicago.
“These data suggest that at similar levels of blood pressure control, the longer-acting, higher-binding telmisartan may confer relatively greater protection against the development of end-stage renal disease, although that hypothesis needs to be tested prospectively,” he said.
Dr. Bakris and associates randomized 860 patients with type 2 diabetes mellitus, hypertension (defined as BP > 130/80 mm Hg), and overt nephropathy to either telmisartan 40 mg or losartan 50 mg for 2 weeks, and then titrated to 80 mg and 100 mg, respectively. If blood pressure was not controlled, concomitant antihypertensives were allowed, except ARBs, ACE inhibitors, and direct vasodilators.
At admission, the average BP was 143/80 mm Hg in both groups; the mean urinary protein to creatinine ratio was 1,971 mg/gCr in the telmisartan group vs. 2,010.5 mg/gCr in the losartan group; and the mean serum creatinine level was 1.54 mg/dL in the telmisartan group vs. 1.55 mg/dL in the losartan group. In all, 827 patients were available for analysis.
After 1 year of treatment, the mean change in the morning spot urinary protein to creatinine ratio—the study's primary end point—was 0.71 for telmisartan and 0.80 for losartan. This translated to a 29% reduction from baseline for telmisartan and a 20% reduction for losartan.
BP reductions were not significant between groups (−4.8/−3.2 mm Hg vs. −2.7/−2.9 mm Hg, respectively).
Adverse events were not different between groups, said Dr. Bakris, who disclosed that he is a consultant and speaker for, and has received research support from, the study sponsor Boehringer Ingelheim.