Effect of DPP4 Inhibition on Vasoconstriction

July 27, 2018 updated by: Nancy J. Brown, MD, Vanderbilt University

Contribution of Neuropeptide Y (NPY) to Vasoconstriction and Sympathetic Activation in the Setting of Dipeptidyl Peptidase IV (DPP4) Inhibition

The purpose of this study is to understand how dipeptidyl peptidase IV (DPP4) inhibition in diabetics affects hemodynamic parameters and sympathetic activation in the setting of increasing concentrations of neuropeptide Y, an endogenous peptide. The central hypothesis is that DPP4 inhibition decreases degradation of neuropeptide Y, resulting in increased vasoconstriction and sympathetic activation.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Dipeptidyl peptidase IV (DPP4) inhibitors are routinely used for the treatment of type II diabetes mellitus (T2DM). Since the prevalence of hypertension is 1.5-3 times greater in diabetics compared to sex-aged matched controls, the use of antihypertensives such as ACE inhibitors is also common in diabetics. DPP4 is involved in the degradation of multiple vasoactive peptides, one of which is neuropeptide Y. This peptide is thought to play a role in blood pressure regulation and sympathetic nervous system activation. The aim of this study is to investigate how DPP4 inhibition affects vasoconstriction in response to increasing neuropeptide Y concentrations. Additionally, the investigators want to understand how the combination of DPP4 inhibition and ACE inhibition affects vasoconstriction and sympathetic activation. Understanding the hemodynamic and neurohumoral changes associated with DPP4 and ACE inhibitors has important implications for the millions of patients with T2DM who take these drugs concurrently.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
18

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Tennessee
      • Nashville, Tennessee, United States, 37232
        • Vanderbilt University Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 55 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

Type 2 Diabetes Mellitus, as defined by one or more of the following,

  • Hgb A1C ≥6.5%, or
  • Fasting plasma glucose ≥126mg/dL, or
  • Two hour plasma glucose ≥200 mg/dL following 75gr oral glucose load

For female subjects the following conditions must be met:

  • Postmenopausal status for at least 1 year, or
  • Status post-surgical sterilization, or
  • If of childbearing potential, utilization of some form of birth control and willingness to undergo β-HCG testing prior to drug treatment and on every study day

Exclusion Criteria:

  • Type 1 diabetes.
  • Poorly controlled T2DM, defined as Hgb A1C>8.7%.
  • Use of anti-diabetic medications other than metformin.
  • Hypertension.
  • Subjects who have participated in a weight-reduction program during the last 6 months and whose weight has increased or decreased more than 5 kg over the preceding 6 months.
  • Pregnancy. Breast-feeding.
  • Treatment with any of the following drugs: cisapride, pimozide, terfenadine, astemizol
  • Clinically significant gastrointestinal impairment that could interfere with drug absorption
  • Cardiovascular disease that would pose risk for the subject to participate in the study, 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 AV block, mitral valve stenosis, or hypertrophic cardiomyopathy.
  • Impaired hepatic function (aspartate amino transaminase [AST] and/or alanine amino transaminase [ALT] >2 x upper limit of normal range)
  • Impaired renal function (eGFR< 60mL/min/1.73m2 as determined by the MDRD equation).
  • History or presence of immunological or hematological disorders.
  • History of pancreatitis or known pancreatic lesions.
  • History of angioedema or cough while taking an ACE inhibitor.
  • Hematocrit <35%.
  • Treatment with anticoagulants.
  • Growth hormone deficiency.
  • Diagnosis of asthma requiring use of an inhaled β-2 agonist more than 1 time per week.
  • 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
  • Treatment with systemic glucocorticoids within the last 6 months.
  • Treatment with lithium salts
  • Ongoing tobacco use or recreational drug use.
  • Treatment with any investigational drug in the 1 month preceding the study
  • Mental conditions rendering the subject unable to understand the nature, scope, or 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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Other: Sitagliptin then Placebo
Subjects in this arm will receive sitagliptin 100 mg daily. After one week of treatment, subjects will report for study day #1. During the study day subjects will be given intra-aterial neuropeptide Y and enalaprilat. A four week washout of medications will occur after the study day. Subjects will then receive placebo for one week followed by study day #2.
Drug: Sitagliptin
Subjects will receive sitagliptin 100 mg daily for 7 days prior to one of the study days.
Other Names:
  • Januvia
Drug: Placebo
Subjects will receive a placebo capsule daily for 7 days prior to one of the study days.
Other Names:
  • Microcrystalline cellulose
Drug: Neuropeptide Y
During the study days, neuropeptide Y will be infused through an intra-arterial line. There will be four doses of neuropeptide Y used (0.1, 0.3, 1.0, and 3.0 nmol/min) and each dose will be infused for 10 minutes.
Other Names:
  • NPY
Drug: Enalaprilat
Ninety minutes after the last dose of neuropeptide Y, enalaprilat will be infused through the intra-arterial line at 0.33 µg/min/100mL of forearm volume. After 30 minutes, a second infusion of neuropeptide Y will begin. Similar to the previous neuropeptide infusion, four doses of neuropeptide Y will be used (0.1, 0.3, 1.0, and 3.0 nmol/min) and each dose will be infused for 10 minutes.
Other Names:
  • Vasotec I.V.
Other: Placebo then Sitagliptin
Subjects in this arm will receive placebo for one week. After this, subjects will report for study day #1. During the study day subjects will be given intra-aterial neuropeptide Y and enalaprilat. A four week washout of medications will occur after the study day. Subjects will then receive 100 mg of sitagliptin daily for one week followed by study day #2.
Drug: Sitagliptin
Subjects will receive sitagliptin 100 mg daily for 7 days prior to one of the study days.
Other Names:
  • Januvia
Drug: Placebo
Subjects will receive a placebo capsule daily for 7 days prior to one of the study days.
Other Names:
  • Microcrystalline cellulose
Drug: Neuropeptide Y
During the study days, neuropeptide Y will be infused through an intra-arterial line. There will be four doses of neuropeptide Y used (0.1, 0.3, 1.0, and 3.0 nmol/min) and each dose will be infused for 10 minutes.
Other Names:
  • NPY
Drug: Enalaprilat
Ninety minutes after the last dose of neuropeptide Y, enalaprilat will be infused through the intra-arterial line at 0.33 µg/min/100mL of forearm volume. After 30 minutes, a second infusion of neuropeptide Y will begin. Similar to the previous neuropeptide infusion, four doses of neuropeptide Y will be used (0.1, 0.3, 1.0, and 3.0 nmol/min) and each dose will be infused for 10 minutes.
Other Names:
  • Vasotec I.V.
Placebo Comparator: Sitagliptin then Placebo: Valsartan
Subjects in this arm will receive sitagliptin 100 mg/d for one week as well as valsartan 160 mg/d for one week. After this subjects will report for study day #1. During the study day, subjects will be given intra-arterial neuropeptide Y. A four week washout of medication will occur after the study day. Subjects will then receive placebo/d and valsartan 160 mg/d for one week followed by study day #2.
Drug: Sitagliptin
Subjects will receive sitagliptin 100 mg daily for 7 days prior to one of the study days.
Other Names:
  • Januvia
Drug: Placebo
Subjects will receive a placebo capsule daily for 7 days prior to one of the study days.
Other Names:
  • Microcrystalline cellulose
Drug: Valsartan 160mg
Valsartan 160 mg/d for 7 days prior to one of the study days.
Other Names:
  • valsartan p.o.
Placebo Comparator: Placebo then Sitagliptin: Valsartan
Subjects in this arm will receive placebo/d for one week as well as valsartan 160 mg/d for one week. After this subjects will report for study day #1. During the study day, subjects will be given intra-arterial neuropeptide Y. A four week washout of medication will occur after the study day. Subjects will then receive sitagliptin 100mg/d and valsartan 160 mg/d for one week followed by study day #2.
Drug: Sitagliptin
Subjects will receive sitagliptin 100 mg daily for 7 days prior to one of the study days.
Other Names:
  • Januvia
Drug: Placebo
Subjects will receive a placebo capsule daily for 7 days prior to one of the study days.
Other Names:
  • Microcrystalline cellulose
Drug: Valsartan 160mg
Valsartan 160 mg/d for 7 days prior to one of the study days.
Other Names:
  • valsartan p.o.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Forearm Blood Flow
Time Frame: FBF measured after 5 min of the 1 nmol/min dose of neuropeptide Y on study days 1 and 2. Study days 1 and two were separated by five weeks.
Forearm blood flow measured by strain gauge plethysmography in response to 1.0 nmol/min neuropeptide Y, the highest dose that all received.
FBF measured after 5 min of the 1 nmol/min dose of neuropeptide Y on study days 1 and 2. Study days 1 and two were separated by five weeks.

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Arterial Norepinephrine
Time Frame: Measured at baseline (time 0) prior to the infusion of neuropeptide Y on each study day. Study days 1 and 2 were separated by five weeks.
Arterial norepinephrine concentration measured by high-performance liquid chromatography.
Measured at baseline (time 0) prior to the infusion of neuropeptide Y on each study day. Study days 1 and 2 were separated by five weeks.
Venous Norepinephrine
Time Frame: Measured at baseline (time 0) prior to the infusion of neuropeptide Y on each study day. Study days 1 and 2 were separated by five weeks.
Venous norepinephrine concentration measured by high-performance liquid chromatography
Measured at baseline (time 0) prior to the infusion of neuropeptide Y on each study day. Study days 1 and 2 were separated by five weeks.
NPY Metabolites
Time Frame: Measured after 5 min infusion of the 1.0 nmol/min dose of neuropeptide Y on study days 1 and 2. Study days 1 and 2 were separated by five weeks.

NPY (3-36) concentration measured by micro ultra-hgih pressure liquid chromatography tandem mass spectrometry.

NPY (3-36) is the degradation product of NPY by dipeptidyl peptidase 4. It was measured only in the diabetics studied.
Measured after 5 min infusion of the 1.0 nmol/min dose of neuropeptide Y on study days 1 and 2. Study days 1 and 2 were separated by five weeks.
Insulin
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days 1 and 2 were separated by five weeks, a four-week washout and one-week treatment period.
Plasma insulin measured by radioimmunoassay.
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days 1 and 2 were separated by five weeks, a four-week washout and one-week treatment period.
GLP-1
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
GLP--1 was not analyzed as subjects were studied in the fasting state.
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Glucose
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Glucose was measured by the glucose oxidase method using a YSI glucose analyzer
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
ACE Activity
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
ACE activity was measured using a commercially available assay (Olympus AU400/AU600, Alpco Diagnotics, Salem, NH.) The lower level of detection was 15 U/L and values below the level of detection were reported at half the level of detection.
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
DPP4 Activity
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
DPP4 activity was measured by detection of cleavage of a colorimetric substrate.
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Low Frequency Variability of Blood Pressure Activity
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Measured using the VITAL-GARD 450c monitor Ivy Biomedical Systems, Branford, CT, USA)
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Arterial tPA
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Measured using an ELISA.
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Venous tPA
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Measured using an ELISA. This was measured in a few subjects. After it was determined that there was no change in net t-PA release it was not measured in the remainder.
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Mean Arterial Pressure
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Heart Rate
Time Frame: Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.
Measured at baseline (time 0) of each study day prior to the infusion of neuropeptide Y. Study days were separated by five weeks, a four-week washout and one-week treatment period.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Vanderbilt University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 1, 2015

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 1, 2017

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 1, 2017

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 16, 2015

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 20, 2015

First Posted (Estimate)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 24, 2015

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 27, 2018

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 27, 2018

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2018

More Information

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Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 151133

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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