Clinical trial NCT00353652: Effects of Thiazide Diuretics on Sympathetic Nervous System in Hypertension
Official title: Neural Mechanisms of Thiazide-induced Insulin Resistance
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE4
Conditions: Hypertension
Keywords: Blood Pressure, High
Lead sponsor: University of Texas Southwestern Medical Center
Sponsor class: OTHER
Collaborators: name: National Heart, Lung, and Blood Institute (NHLBI)
First posted: 2006-07-19
Enrollment: 166
Sex: ALL
Minimum age (years): 18
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: TREATMENT

Brief summary: Thiazide medications are often prescribed for individuals with high blood pressure, but research has shown that they may increase an individual's risk of developing diabetes. While it is unknown exactly how thiazide causes this response, it is likely that the nervous system is somehow involved. This study will evaluate the role of the nervous system in sugar metabolism, as well as determine the effect of thiazide and other medications on individuals with high blood pressure.

Detailed description: Thiazide medications, including chlorthalidone, are commonly prescribed for individuals with high blood pressure because they are inexpensive, effective at lowering blood pressure, and able to reduce the risk of heart failure and stroke. Despite these advantages, research has shown that thiazide medications may increase an individual's risk of developing diabetes. The exact mechanism that causes this remains unknown. Thiazide appears to increase sympathetic nervous system activity, thereby decreasing glucose reuptake and metabolism by skeletal muscle tissues. In turn, this tends to contribute to glucose intolerance and the development of diabetes. More research, however, is needed to confirm this link. Spironolactone, another blood pressure medication, does not pose the same risk for developing diabetes and may prove beneficial as a primary treatment for high blood pressure. The purpose of this study is to determine the role of the sympathetic nervous system in glucose metabolism in individuals with high blood pressure, as well as compare the effectiveness of thiazide, spironolactone, and other antihypertensive medications in reducing blood pressure. Results from this study may initiate the development of future clinical trials involving spironolactone as a primary treatment for reducing blood pressure.

This study will enroll individuals with high blood pressure. Study# 1: All subjects were randomized to receive 3 months chlorthalidone (12.5-25 mg/d) or spironolactone (50-75 mg/d), using a single-blind 2-phase crossover design without washout between treatments. Each subject was followed every 4 wk for measurement of 24-h ambulatory BP and serum potassium (K). The doses of chlorthalidone and spironolactone were titrated to achieve 24-h ambulatory BP of less than 130/80mmHg in the same subject. During chlorthalidone treatment period, subject was given oral K supplementation according to a sliding scale to maintain serum K from 4.0-4.5 mmol/liter. Then, sympathetic nerve activity (SNA) is measured after 3 months of chlorthalidone and after 3 months of spironolactone. Arterial baroreflex sensitivity, glucose, and insulin are measured at baseline, after 3 months of chlorthalidone, and after 3 months of spironolactone. Insulin sensitivity will be measured using HOMA-IR. Study #2: All subjects are randomized to 3 months of fixed-dose Chlorthalidone 25 mg once daily alone, fixed-dose Chlorthalidone 25 mg once daily plus fixed-dose Spironolactone 25 mg once daily, and fixed-dose Chlorthalidone 25 mg once daily plus fixed-dose Irbesartan 150 mg once daily, using a single-blind 3-phase crossover design without washout between treatments. Then, SNA , Arterial baroreflex sensitivity, glucose, and insulin are measured after 3 months of each treatment phase.

Eligibility criteria: Inclusion Criteria:

* Untreated stage 1 primary hypertension (systolic blood pressure between 140 to 159 mm Hg and diastolic blood pressure between 90 to 99 mm Hg)

Exclusion Criteria:

* Cardiopulmonary disease, as determined by medical history or by physical examination
* Serum creatinine greater than or equal to 1.5 mg/dL
* Diabetes mellitus or other systemic illness
* Left ventricular hypertrophy by echocardiography or ECG
* Hypersensitivity to chlorthalidone, spironolactone, eplerenone, angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blocker, insulin, Evans blue dye, or clonidine
* History of substance abuse (other than tobacco)
* History of gouty arthritis
* History of ACE inhibitor-induced cough or angioedema
* Evidence of secondary hypertension
* Pregnant

Primary outcomes:
measure: Sympathetic Nerve Activity
timeFrame: Measured at 3 months
Secondary outcomes:
measure: 24-hour Ambulatory Systolic Blood Pressure
timeFrame: Measured at 3 months
measure: Insulin
timeFrame: 3 months
measure: HOMA-IR
timeFrame: 3 months
measure: Sympathetic Baroreflex Sensitivity
timeFrame: 3 months
Other outcomes:
Locations:
city: Dallas
country: United States
facility: University of Texas Southwestern Medical Center at Dallas
state: Texas
city: Dallas
country: United States
facility: University of Texas Southwestern Medical Center
state: Texas
Study officials:
affiliation: University of Texas, Southwestern Medical Center at Dallas
name: Wanpen Vongpatanasin, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Raheja P, Price A, Wang Z, Arbique D, Adams-Huet B, Auchus RJ, Vongpatanasin W. Spironolactone prevents chlorthalidone-induced sympathetic activation and insulin resistance in hypertensive patients. Hypertension. 2012 Aug;60(2):319-25. doi: 10.1161/HYPERTENSIONAHA.112.194787. Epub 2012 Jun 25.
citation: Kontak AC, Wang Z, Arbique D, Adams-Huet B, Auchus RJ, Nesbitt SD, Victor RG, Vongpatanasin W. Reversible sympathetic overactivity in hypertensive patients with primary aldosteronism. J Clin Endocrinol Metab. 2010 Oct;95(10):4756-61. doi: 10.1210/jc.2010-0823. Epub 2010 Jul 21.