Chronic diuretic therapy with moderate doses of triamterene is not associated with folate deficiency

The diuretic drug triamterene has previously been shown to be a competitive inhibitor of folate absorption in the rat intestine (J Lab Clin Med 1986;108:272-6). We therefore investigated whether human subjects who are taking the drug on a long-term basis are at increased risk of folate deficiency. In each of two free-living populations, a study was performed to compare the folate status of triamterene users with those not taking the drug. The first population consisted of 272 elderly individuals not living in institutions who were participants in a nutrition status survey and who were taking a variety of antihypertensive medications; 32 of these individuals were daily users of triamterene. The hemoglobin concentration, red blood cell (RBC) count, and mean corpuscular volume (MCV) values were not significantly different between the triamterene users and nonusers. The female triamterene users had a slightly higher serum folate level than the female nonusers (p less than 0.04); a similar pattern was observed among the men, although the difference was not statistically significant. The second population consisted of 27 individuals attending a hypertension clinic; 18 subjects were taking 50 to 150 mg of triamterene per day and nine were taking antihypertensive drugs other than triamterene. The hemoglobin concentration, RBC count, MCV, serum folate values, and RBC folate values were found to not differ significantly between the triamterene users and the hypertensive controls (p greater than 0.05). These data suggest that chronic triamterene administration in individuals not living in institutions, at the doses examined in this study, is not associated with indications of folate deficiency.