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Study of Sildenafil Citrate on Insulin Resistance in African American

This study has been completed.
National Heart, Lung, and Blood Institute (NHLBI)
Information provided by (Responsible Party):
Cyndya Shibao, Vanderbilt University Medical Center Identifier:
First received: April 11, 2011
Last updated: February 22, 2017
Last verified: February 2017

Obesity has a greater detrimental impact on the health of African American women than on any other racial or gender group. Nearly 80% of African American women are overweight or obese in the United States. Hypertension and insulin resistance are more prevalent among African American women as compared to men and Caucasians. These conditions put them at increased risk for the development of diabetes mellitus and cardiovascular disease.

Recent studies have reported that a substance named Nitric Oxide (NO)may have some beneficial effect on how the body handles blood sugar and blood pressure. Of interest,some studies have shown that African Americans have decreased function of NO in their blood vessels.

In this study proposal the investigators will test if increasing NO function with a PDE-5 inhibitor (sildenafil citrate) will improve pre-diabetes and the health of the inner layer of the blood vessels in obese African American women.

Condition Intervention Phase
Metabolic Syndrome
Drug: Sildenafil
Drug: Placebo
Phase 1
Phase 2

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Participant, Care Provider, Investigator, Outcomes Assessor
Primary Purpose: Other
Official Title: Effect of Sildenafil Citrate on Insulin Resistance and Endothelial Function in Obese African American Women

Resource links provided by NLM:

Further study details as provided by Vanderbilt University Medical Center:

Primary Outcome Measures:
  • Insulin Sensitivity [ Time Frame: Insulin sensitivity measured at baseline and 4 weeks after the intervention ]
    insulin sensitivity as measured by frequently sampled intravenous glucose tolerance test

Secondary Outcome Measures:
  • Endothelial Function [ Time Frame: Difference between FMD at baseline and 4 weeks ]
    Endothelial function was measured with flow mediated dilation, percent change

Enrollment: 46
Study Start Date: April 2011
Study Completion Date: August 2013
Primary Completion Date: August 2013 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Sildenafil
Sildenafil 20 mg three times a day
Drug: Sildenafil
20 mg three times a day.
Other Name: Revatio
Placebo Comparator: Placebo
Drug: Placebo
No active drug


Ages Eligible for Study:   18 Years to 60 Years   (Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Race will be self-defined, but only subjects who report both parents of the same race will be included.
  • Age 18-60 years old.
  • The investigators will recruit subjects with wide range of BMI 30-45 kg/m2.
  • Subjects who have metabolic syndrome or who have a fasting insulin >13. The diagnosis include 3 of the following:

Fasting blood glucose of greater than 100 Triglyceride levels of greater than 150 HDL cholesterol of less than 50 in women Blood pressure of at least 130/85, or on blood pressure medicine Waist girth of more than 35 inches in women. Subjects of childbearing potential will be required to have a negative serum/urine pregnancy test. In addition, they will be asked to use a reliable contraceptive method prior to enrollment as determined by the PI (Dr. Cyndya Shibao).

Exclusion Criteria:

  • Previous allergic reactions to any of the study medication (sildenafil) or inability to take study medications as prescribed during the course of the study.
  • Type 1 or 2 diabetes mellitus as defined by a fasting glucose of 126 mg/dl or greater.
  • Use of antidiabetic medication (insulin, metformin, sulfonylurea, troglitazone)
  • Cardiovascular disease such as myocardial infarction within 6 months prior to enrollment, presence of angina pectoris, significant arrhythmia, congestive heart failure (LV hypertrophy acceptable), deep vein thrombosis, pulmonary embolism, second or third degree heart block, mitral valve stenosis, aortic stenosis or hypertrophic cardiomyopathy.
  • Current smokers.
  • Significant weight change >5% from baseline in the past three months.
  • Pregnancy or breast-feeding.
  • History of serious neurological disease such as cerebral hemorrhage stroke, transient ischemic attack.
  • History or presence of immunological or hematological disorders.
  • Clinical significant gastrointestinal impairment that could interfere with drug absorption.
  • Impaired hepatic function (aspartate amino transaminase [AST] and/or alanine amino transaminase [ALT] >1.5X upper limit of normal range).
  • Impaired renal function (estimated glomerular filtration rate (eGFR) of <60mL/min).
  • Any underlying or acute disease requiring regular medication which could possibly pose a threat to the subject or make implementation of the protocol or interpretation of the study results difficult.
  • History of alcohol or drug abuse.
  • Mental conditions rendering the subject unable to understand the nature, scope and possible consequences of the study.
  • Inability to comply with the protocol, e.g. uncooperative attitude, inability to return for follow-up visits, and unlikelihood of completing the study.
  • Patients must not be taking nitratest in any form (e.g., nitroglycerin, isosorbide dinitrate, nitroprusside, and others) during this study
  • Patients on alpha-blocking drugs (doxazosin, terazosin , or prazosin) will be excluded
  • Patients on protease inhibitors (ritonavir and others) will be excluded
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Please refer to this study by its identifier: NCT01334554

United States, Tennessee
Vanderbilt University
Nashville, Tennessee, United States, 37232
Sponsors and Collaborators
Vanderbilt University Medical Center
National Heart, Lung, and Blood Institute (NHLBI)
Principal Investigator: Cyndya Shibao, MD Vanderbilt University
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Cyndya Shibao, Assistant Professor of Medicine, Vanderbilt University Medical Center Identifier: NCT01334554     History of Changes
Other Study ID Numbers: 100713
K23HL103976 ( US NIH Grant/Contract Award Number )
Study First Received: April 11, 2011
Results First Received: January 28, 2015
Last Updated: February 22, 2017
Individual Participant Data  
Plan to Share IPD: No

Keywords provided by Vanderbilt University Medical Center:
African American
Metabolic Syndrome
Endothelial function
Sildenafil citrate

Additional relevant MeSH terms:
Metabolic Syndrome X
Insulin Resistance
Glucose Metabolism Disorders
Metabolic Diseases
Sildenafil Citrate
Citric Acid
Vasodilator Agents
Phosphodiesterase 5 Inhibitors
Phosphodiesterase Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Urological Agents
Calcium Chelating Agents
Chelating Agents
Sequestering Agents processed this record on April 28, 2017