Abstract 426: Blood Pressure Lowering Effect of Triamterene
Triamterene is a potassium-sparing diuretic, often used in combination with thiazide diuretics for treatment of hypertension. By inhibiting the epithelial sodium channel (ENaC) in collecting duct, it reduces potassium secretion, thus reducing the risk of hypokalemia. But it is unclear whether triamterene also has a blood pressure (BP)-lowering effect. We conducted an observational study to examine the BP effect of triamterene. We extracted medical records of 1723 patients diagnosed with hypertension from an urban hospital. There were 1375 patients on hydrochlorothiazide (HCTZ) alone and 348 patients on a combination of HCTZ and triamterene. We compared the recorded BP using regression analysis and the propensity score method. Patient characteristics of the two treatment groups were largely comparable, except for patients on the combination therapy were more likely to be female (83% vs 66%; p<0.001), slightly older (44.7 vs 42.4 years; p=0.0021), and had more recorded chronic kidney disease diagnosis (1.7% vs 0.5%). Direct comparison showed that mean systolic-BP in the patients on triamterene was lower (132.3 vs 136.8 mmHg; p<0.001). Regression analysis showed that systolic BP was 3.06 mmHg (p=0.0005) lower in patients on combination therapy, after adjusting for patient’s demographic and clinical characteristics. Finally, we estimated the propensity of each patient receiving the combination therapy using a logistic regression model and then classified patients into five homogeneous subgroups based on their estimated propensity values. The combined subgroup analysis showed that mean systolic BP in the triamterene group was 4.66 mmHg lower (p=0.0006). All analyses consistently point to a lower BP in patients who received triamterene, as compared to patients who received HCTZ alone. In conclusion, ENaC inhibition with triamterene at doses that are potassium-sparing also lower BP. The use of triamterene in combination with HCTZ may have antihypertensive properties that heretofore were underappreciated.
- © 2013 by American Heart Association, Inc.