title: Triamterene Enhances the Blood Pressure Lowering Effect of Hydrochlorothiazide in Patients with Hypertension.
abstract: BACKGROUND
  Triamterene, because of its potassium-sparing properties, is frequently used in combination with hydrochlorothiazide (HCTZ) to treat patients with hypertension. By inhibiting the epithelial sodium channel (ENaC) in the cortical collecting duct, triamterene reduces potassium secretion, thus reducing the risk of hypokalemia. Whether triamterene has an independent effect on blood pressure (BP) has not been well studied.
  
  
  OBJECTIVE
  To determine if triamterene provides an effect to further lower BP in patients treated with HCTZ.
  
  
  METHODS
  We conducted an observational study using electronic medical record data from the Indiana Network for Patient Care. Participants were 17,291 patients with the diagnosis of hypertension between 2004 and 2012.
  
  
  METHODS
  BP was the primary outcome. We compared the BP between patients who were taking HCTZ, with and without triamterene, either alone or in combination with other antihypertensive medications, by using a propensity score analysis. For each medication combination, we estimated the propensity score (i.e., probability) of a patient receiving triamterene using a logistic regression model. Patients with similar propensity scores were stratified into subclasses and BP was compared between those taking triamterene or not within each subclass; the effect of triamterene was then assessed by combining BP differences estimated from all subclasses.
  
  
  RESULTS
  The mean systolic BP in the triamterene + HCTZ group was 3.8 mmHg lower than in the HCTZ only group (p < 0.0001); systolic BP was similarly lower for patients taking triamterene with other medication combinations. Systolic BP reduction was consistently observed for different medication combinations. The range of systolic BP reduction was between 1 and 4 mm Hg, depending on the concurrently used medications.
  
  
  CONCLUSIONS
  In the present study, triamterene was found to enhance the effect of HCTZ to lower BP. In addition to its potassium-sparing action, triamterene's ability to lower BP should also be considered.
authors.affiliation: Department of Biostatistics, Indiana University School of Medicine, 410 West 10th Street, Indianapolis, IN, 46202, USA. wtu1@iu.edu.|Indiana University Center for Aging Research, Indianapolis, IN, 46202, USA. wtu1@iu.edu.
authors.forename: Wanzhu
authors.initials: W
authors.lastname: Tu
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Decker
authors.affiliation: Department of Biostatistics, Indiana University School of Medicine, 410 West 10th Street, Indianapolis, IN, 46202, USA.
authors.forename: Zangdong
authors.initials: Z
authors.lastname: He
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors.forename: Blake L
authors.initials: BL
authors.lastname: Erdel
authors.affiliation: Department of Biostatistics, Indiana University School of Medicine, 410 West 10th Street, Indianapolis, IN, 46202, USA.
authors.forename: George J
authors.initials: GJ
authors.lastname: Eckert
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors.forename: Richard N
authors.initials: RN
authors.lastname: Hellman
authors.affiliation: Indiana University Center for Aging Research, Indianapolis, IN, 46202, USA.|Purdue University College of Pharmacy, West Lafayette, IN, 47907, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Murray
authors.affiliation: Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 46202, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Oates
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors.forename: J Howard
authors.initials: JH
authors.lastname: Pratt
mesh_terms: D001794:Blood Pressure / Q000187:drug effects*; D004232:Diuretics / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006852:Hydrochlorothiazide / Q000008:administration & dosage*; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome; D014223:Triamterene / Q000008:administration & dosage*
chemical_list: D004232:Diuretics; D006852:Hydrochlorothiazide; D014223:Triamterene