Peripheral Vascular Effects of Sulfhydryl-containing Antihypertensive Pharmacotherapy on Microvessels in Humans

Phase 1

Terminated

Conditions: Hypertension,Essential

Interventions: Drug: Captopril Pill
Drug: Enalapril Pill
Drug: Hydrochlorothiazide

Registration Number: NCT03179163

Lead Sponsor: Penn State University

Brief Summary: High blood pressure can cause physical changes to the blood vessels of the body (remodeling). If a person who has high blood pressure also has a lot of blood vessel remodeling with their condition, they are more likely to have poor results with medical treatment for hypertension. The researchers examine the impact of different classes of drugs that doctors use to treat high blood pressure (hypertension) on blood vessel remodeling. Some drugs that doctors prescribe for their patients contain a "sulfhydryl group" (a sulfur atom bonded to a hydrogen atom). Drugs that have the sulfhydryl group may reduce blood vessel remodeling more that drugs that do not. For this study, participants who have high blood pressure perform the experiments, take a drug for 16-weeks to lower blood pressure, and repeat the experiments. The researchers randomly assign one of three drugs to participants who have high blood pressure: a diuretic ("water pill"), a drug containing a sulfhydryl (SH) group, or a drug that does not contain a sulfhydryl group. Participants who do not have high blood pressure perform the experiments, but do not take any of the drugs. In some of our experiments, the researchers use a technique called "microdialysis" (MD). With MD, the researchers perfuse some research drugs into the skin on the forearm through tiny tubing that mimics capillaries. These MD drugs mimic or block substances the body naturally makes to control the small blood vessels in the skin. The drugs remain in nickel-sized areas around the tubing and do not go into the rest of the body. The researchers also analyze very small skin samples (skin biopsy) obtained from the forearm. Lastly, the researchers use a standard technique called "flow mediated dilation" (FMD) that uses blood pressure cuffs and ultrasound to look at the health of larger blood vessels in the body. FMD includes placing a small tablet of nitroglycerin under the tongue during part of the test.

Detailed Description: Upon initial screening and again within a week of testing, all subjects will have an assessment of 24-hour ambulatory blood pressure. Subject screening will be performed by the Penn State Clinical Translational Research Center (CTRC) medical staff and will include a physical exam by a clinician, anthropometry, and a chemical and lipid profile, liver and renal function. Women will be either postmenopausal (absence of menstruation of \>1 year and Follicle Stimulating Hormone (FSH) \>25 milli-international units per milliliter (mlU/ml)) and not be taking hormone replacement therapy, or normally menstruating and tested in the early follicular phase of their cycle. Subjects will also go through an assessment of conduit vessel endothelial and vascular smooth muscle function with brachial artery flow-mediated vasodilation (FMD), and sublingual nitroglycerin.

Subjects will undergo initial microdialysis experiments and biopsy samples will be obtained. Subjects will then be randomly assigned to treatment group. Blood pressure will be monitored every 2 weeks and weekly compliance checks will be made by the researcher's nurse coordinator. 24-hour ambulatory blood pressure monitoring will be conducted monthly to determine the efficacy of antihypertensive treatment and to inform dosing titration. Examining pharmacokinetic and dynamic data from the literature indicate that blood pressure lowing and peripheral vascular effects are maximized by 12 weeks of antihypertensive therapy and maintained thereafter. After 16 weeks of the assigned intervention, subjects will repeat microdialysis experiments and additional cutaneous biopsy samples will be obtained. Conduit artery measures including brachial artery FMD and responsiveness to sublingual nitroglycerin will also be evaluated at this time.

Recruitment & Eligibility

Status: TERMINATED

Sex: All

Target Recruitment: 10

Inclusion Criteria

Women and men
40-65 years
Blood pressure: Normotensive <120/80 mmHg Hypertensive ≥140/90 mmHg and <160/110 mmHg
HbA1C of <6.5%
Women are post-menopausal and not taking hormone replacement therapy, or have normal cycles and are tested in the early follicular phase
Subjects may or may not be taking one doctor-prescribed drug to lower blood pressure (e.g. diuretic, ACE inhibitor).
- Must be able to stop physician-prescribed antihypertensive drug for the duration of the subject's participation in the study (with the approval of their personal physician).

Exclusion Criteria

Relevant to all subjects:

current medications which could conceivably alter the cardiovascular or thermoregulatory control or responses (e.g. beta blockers, calcium channel blockers, ACE inhibitors, angiotensin receptor blockers)
taking a diuretic (also see below)
allergy to test substances
allergy to latex
nicotine use (smoking, chewing tobacco, etc.)
illegal/recreational drug use
pregnancy or breastfeeding
diabetes

Relevant to hypertensive subjects only:

contraindication for all three pharmacotherapy drugs used in this study

o Note: Subjects who have a contraindication (e.g. a condition, medication with a known interaction, known allergy) to only one or two of the three pharmacotherapy drugs, may be assigned one of the pharmacotherapy drugs that is not contraindicated.
history of having taken an ACE inhibitor with antioxidant properties (e.g. Captopril, Zofenopril)
kidney problems
liver problems
history of heart disease or failure
history of blood clots or stroke
angioedema
electrolyte imbalance
planned surgery requiring general anesthesia during the pharmacotherapy period
peripheral vascular disease
diuretics (a subject taking only a diuretic to control the subject's hypertension may be included in the study if the subject stops taking the diuretic for the duration of the subject's participation in the study with the approval of the subject's personal physician.)

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Hypertensive - ACE inhibitor with sulfahydrl donor (ACEi +SH)	Captopril Pill	Captopril Pill intervention Blood Pressure ≥140/90 mmHg and \<160/110 mmHg
Hypertensive - ACE inhibitor (ACEi)	Enalapril Pill	Enalapril Pill intervention Blood Pressure ≥140/90 mmHg and \<160/110 mmHg
Hypertensive - Diuretic	Hydrochlorothiazide	Hydrochlorothiazide intervention Blood Pressure ≥140/90 mmHg and \<160/110 mmHg

Primary Outcome Measures

Name	Time	Method
Change in Endothelium Dependent Vasodilation	16 weeks	This measurement is performed using a laser Doppler flow meter. The flow meter produces a non-invasive qualitative and dimensionless index of blood flow in blood vessels during the localized perfusion of the endothelium-dependent vasodilatory acetycholine in a dose response fashion. The results are the differences in the area under the curve units=(laser Doppler flux/MAP)\*logAch concentration

Secondary Outcome Measures

Name	Time	Method
Diastolic Blood Pressure	16 Weeks	Blood pressure is measured via brachial auscultation manually or with a critical care monitor. The lowest blood pressure during a cardiac cycle when the heart is between beats.
Systolic Blood Pressure	16 Weeks	Blood pressure is measured via brachial auscultation manually or with a critical care monitor. The peak blood pressure during a cardiac cycle when the heart contracts.