Study 1: Effect of Minocycline Treatment on Drug-Resistant Hypertensive Patients

Angiotensin and Neuroimmune Activation in Hypertension

Hypertension (HTN) is the single most prevalent risk factor for cardiovascular disease, diabetes, obesity and metabolic syndrome. Recent American Heart Association (AHA) statistics indicate that one-third of all adults in the United States of America suffer from HTN. Despite advances in life style modification and multi-drug therapies, 20-30% of all hypertensive patients remain resistant.

These individuals exhibit autonomic dysregulation due to elevated sympathetic activity and norepinephrine spillover, and low parasympathetic activity. It is generally accepted that this uncontrolled, resistant HTN is primarily "neurogenic" in origin, involving over activity of the sympathetic nervous system that initiates and sustains HTN. A surgical approach such as the recently developed "Simplicity Catheter" assisted renal denervation remains one of the few options available to these patients. Thus, a mechanism-based breakthrough is imperative to develop novel strategies to prevent and perhaps eventually cure neurogenic hypertension (NH). This study is designed to evaluate a low and high dose of minocycline to test the hypothesis that minocycline treatment would produce antihypertensive effects in drug-resistant neurogenic hypertensive individuals. Minocycline has been selected because of its demonstrated effects on inhibiting microglial activation and its ability to penetrate the blood brain barrier. There is no other compound available that is safer and displays specificity better than Minocycline in inhibiting microglial activation. Thus, the potential therapeutic benefits of this inexpensive, well tolerated, already FDA-approved drug that has minimal side effects would be enormous.

Study Overview

• Status: Completed
• Conditions: Hypertension
• Intervention / Treatment: Drug: Minocycline 50mg/d; Drug: Minocycline 100mg/d; Device: Minocycline 200mg/d

Detailed Description

Open-label design of dose titration for each participant beginning at 50 mg/day of minocycline, escalating to 100 mg/day and 200 mg/day if the primary outcome measure of ambulatory blood pressure monitor (ABPM) =/> to 5 mmHg decrease in mean daytime SBP was not achieved. If patients responded, participation was completed. This revised protocol was resubmitted to the IRB and approved on 1/6/16. An interim analysis was planned after 40 patients completed the revised protocol.

In addition to blood collection, a physical exam will be conducted and office systolic blood pressure (BP), diastolic blood pressure (DBP) and pulse pressure (PP) will be recorded. Patients will be fitted with an ABPM system. Patients will wear the ABPM for 24 hours at which point they will mail the monitor back to research personnel. At this visit, the study drug will be dispensed and patients will be instructed to start the study medication after completing the 24- hour ABPM monitoring period. After this visit, patients will be asked to return every month till the end of the study at 6 months.

Monthly visits (1, 2, 3, 4, 5 and 6 month visits), will include a brief physical examination and an assessment of medication compliance and tolerance. One tablespoon of blood will be drawn for flow cytometry analysis, selected cytokines, markers of gut permeability including zonulin, and iPSCs isolation at the baseline, 3 and 6 month visit only. Study drug will be dispensed and measurement of SBP, DBP, PP and other vital signs will also be completed. Office BP readings will be taken in a seated position after 5 minutes of rest according to Joint National Committee VII Guidelines. At baseline, BP will be measured at each arm, and the arm with the higher BP will be used for all subsequent readings. Averages of the triplicate measures will be calculated and used for analysis. At baseline and each followup visit, patients will be asked to wear the ABPM for 24 hours. Subjects will mail the cuff back to research personnel when completed. ABPM will be performed using an oscillometric Spacelabs 90207 monitor (Spacelabs Healthcare, Issaqua, WA) with readings taken every 30 minutes in daytime and every 60 minutes at nighttime. ABPM readings will be averaged for, daytime and nighttime. Patients will be assessed while adhering to their usual diurnal activity and nocturnal sleep routine. The antihypertensive drugs, and their doses, used at each visit will be recorded on standardized forms along with any reports of adverse experiences known to occur with the drugs used (e.g. lightheadedness, dizziness, syncope, etc.).

If patients respond to treatment, by protocol defined drop in daytime ABPM and/or the need for down titration of hypertensive therapy they will be considered a responder, complete the final visit and complete study participation. At the final visit, the same blood tests at baseline will be repeated. When the patients complete the 6 months of treatment or are considered a responder at a lower dose, they will come in for their final visit, and return the ABPM monitor, their participation in the trial will be considered as complete.

• Study Type: Interventional
• Enrollment (Actual): 34
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • Florida
    • Gainesville, Florida, United States, 32610
      • UF Health Cardiovascular Clinic

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion:

• Greater than 18 and less than 86 years of age;
• On stable medication regimen
• Full-tolerated doses of 3 or more antihypertensive medications of different classes, one of which must be a diuretic (with no changes for a minimum of two months prior to screening) that is expected to be maintained without changes for at least 3 months.
• The individual agrees to have all study procedures performed
• Willing to provide written consent

Exclusion

• eGFR of < 45mL/min/1.73m2, using the MDRD calculation.
• More than one in-patient hospitalization for an antihypertensive crisis within the year.
• More than one episode(s) of orthostatic hypotension (reduction of SBP of ≥ 20mmHg of diastolic blood pressure (DBP) of ≥ 10mmHg within 3 minutes of standing).
• Known hypersensitivity or contraindication to Minocycline or other tetracycline.

• Evidence of alcoholism or drug abuse;

  • Concurrent severe disease (such as neoplasm or HIV positive or AIDS).
  • Women of childbearing potential

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Minocycline (50 mg/d); Subjects received minocycline 50mg/d.	Drug: Minocycline 50mg/d; Subjects will receive minocycline 50mg if no mean daytime ABPM SBP decline =/> 5mm Hg; subjects will receive minocycline 100mg, if no mean daytime ABPM SBP decline =/> 5mm Hg BP subjects will receive minocycline 200 mg.
Experimental: Minocycline (100 mg/d); Subjects received minocycline 50mg escalating to 100 mg/d.	Drug: Minocycline 100mg/d; Subjects will receive minocycline 50mg if no mean daytime ABPM SBP decline =/> 5mm Hg; subjects will receive minocycline 100mg, if no mean daytime ABPM SBP decline =/> 5mm Hg BP subjects will receive minocycline 200 mg.
Experimental: Minocycline (200 mg/d); Subjects received minocycline 50mg escalating to 100 mg then 200 mg/d.	Device: Minocycline 200mg/d; Subjects will receive minocycline 50mg if no mean daytime ABPM SBP decline =/> 5mm Hg; subjects will receive minocycline 100mg, if no mean daytime ABPM SBP decline =/> 5mm Hg BP subjects will receive minocycline 200 mg.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Categorical Classification of Subjects Into Responders vs. Non-responders	The primary measure of interest was the categorical classification of subjects into responders vs. non-responders upon treatment with a specific minocycline dose: 50, 100 or 200 mg/d. Responders are defined as subjects who achieve a drop of >5 mmHg in mean daytime SBP, based on daytime ABPM measurements (7 am to 10 pm). For these participants, the discontinuation or lowering of the dose of a concurrent anti-hypertensive drug due to excessive SBP reduction will also be assessed. Excessive SBP reduction is defined as an office SBP <120 mmHg or >10 mmHg SBP decrease associated with symptom(s). On the other hand, non-responders are defined as the participants that fail to show any change in their average daytime SBP measured through ABPM despite being exposed to the different minocycline doses evaluated.	180 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in 24 Hour SBP by ABPM	Among Responders, difference in overall daytime and nighttime Systolic Blood Pressure (SBP) using 24 hour Ambulatory Blood Pressure Monitoring (ABPM) from baseline to final visit	180 days
Changes in Office SBP Over Time	Among Responders, evaluation of changes in office systolic blood pressure (SBP) from baseline to final visit	180 days

Collaborators and Investigators

• Sponsor: University of Florida
• Collaborators: National Heart, Lung, and Blood Institute (NHLBI)
• Investigators: Principal Investigator: Carl Pepine, MD, University of Florida

Study record dates

Study Major Dates

• Study Start: October 1, 2014
• Primary Completion (Actual): November 1, 2018
• Study Completion (Actual): November 1, 2018

Study Registration Dates

• First Submitted: May 6, 2014
• First Submitted That Met QC Criteria: May 6, 2014
• First Posted (Estimated): May 8, 2014

Study Record Updates

• Last Update Posted (Estimated): October 23, 2025
• Last Update Submitted That Met QC Criteria: October 9, 2025
• Last Verified: October 1, 2025

More Information

Terms related to this study

• Keywords: Resistent Hypertension
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Hypertension; Organic Chemicals; Hydrocarbons; Hydrocarbons, Cyclic; Polycyclic Aromatic Hydrocarbons; Hydrocarbons, Aromatic; Polycyclic Compounds; Naphthacenes; Tetracyclines; Minocycline
• Other Study ID Numbers: IRB2015005 -N; RO1HL3361028 (Other Identifier: NHLBI); 2013-00102 Study 1 (Other Identifier: UF IRB ID); 1R01HL132448-01 (U.S. NIH Grant/Contract)