HDCN Article Review/Hyperlink

Bakris GL, Smith A

Effects of sodium intake on albumin excretion in patients with diabetic nephropathy treated with long acting calcium antagonists

Ann Int Med (Aug) 125:201-204 1996

Whereas the proteinuria reducing effects of ACE inhibitors are well documented, the effects of other drug classes remain somewhat controversial. In this small study Bakris put 15 patients with NIDDM on once-daily nifedipine, and then on once-daily diltiazem, and studied the effects of these two CCBs on proteinuria. While on each CCB, diet was also altered; there was a 4-week period of a 50 mEq/day sodium diet and a 4-week period on a 250 mEq/day sodium diet.

Each drug reduced the diastolic BP from a mean of 101 to about 80 mm Hg. However, nifedipine had no effect on urinary protein excretion, which remained about 3 gm/day. Diltiazem lowered urinary protein excretion by 50% on the low sodium diet, but had no significant effect on the high sodium diet. The results suggest that reductions in sodium intake, which are known to further reduce proteinuria in patients taking ACE inhibitors, are of key importance to the anti-proteinuric effects of diltiazem. The results are in accord with a study in rats, suggesting that a low sodium diet expresses a diltiazem-associated change in glomerular permeability (Jyothirmay and Reddi, Hypertens 1993:21:795-802).

Comment: The unstated clinical implications seem to be: CCBs are not a good drug for proteinuric hypertensive diabetics if one goal is to reduce the amount of proteinuria. However, in diabetics taking diltiazem, salt restriction may be of some additional benefit. (John T. Daugirdas, M.D., University of Illinois at Chicago)