A Phase 4 interventional study of Spironolactone (drug) and Candesartan 8mg in Hypertension, sponsored by Ottawa Hospital Research Institute. Not yet recruiting at 4 sites in Canada. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-14.
Sponsored by Ottawa Hospital Research Institute · Phase 4, Interventional, and Treatment
The goal of this clinical trial is to determine whether a renin-guided antihypertensive treatment strategy is feasible to implement in community primary care clinics and to explore whether spironolactone improves blood pressure control in adults with low-renin hypertension.
The main questions it aims to answer are:
Is it feasible to identify, recruit, randomize, and follow adults with low-renin hypertension in a pragmatic primary care-based clinical trial?
Does first-line treatment with spironolactone result in greater reductions in ambulatory blood pressure compared with standard first-line antihypertensive therapy among adults with low-renin hypertension?
Researchers will compare spironolactone 25 mg daily with standard first-line antihypertensive therapy (candesartan, hydrochlorothiazide, or amlodipine) to determine whether spironolactone provides better blood pressure control in adults with low-renin hypertension.
Participants will:
Undergo blood pressure assessments, blood tests, and ambulatory blood pressure monitoring (ABPM) to determine eligibility.
Be randomly assigned to receive either spironolactone or a standard first-line antihypertensive medication for 12 weeks.
Complete follow-up visits and laboratory testing to monitor blood pressure response, kidney function, electrolyte levels, medication adherence, and side effects.
Undergo repeat blood pressure measurements and ABPM at the end of the study.
6,114 studies on the registry are indexed under Hypertension; 912 are open to participants now.
This study's planned enrollment of 30 is below the median of 100 across 4,575 interventional studies indexed under Hypertension.
Browse Hypertension studies →Ottawa Hospital Research Institute is the lead sponsor of 547 studies on the registry; 99 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Either:
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Washout period
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Spironolactone 25 mg daily
Drug: Spironolactone (drug)
Participants randomized to standard therapy will undergo secondary randomization to candesartan (8 mg daily), hydrochlorothiazide (25 mg daily), or amlodipine (5 mg daily)
Drug: Candesartan 8mg · Drug: Hydrochlorothiazide (HCTZ) 25 milligrams. · Drug: Amlodipine (5mg)
Spironolactone 25 mg daily: Spironolactone is a widely available and inexpensive MR antagonist medication which blocks the action of aldosterone. Spironolactone is the most commonly recommended drug for the treatment of primary aldosteronism given its efficacy in improving blood pressure and reducing cardiovascular and kidney disease risk for this patient population, with 25 mg being the standard starting dose.
Comparator medications were selected because they represent common guideline-recommended first-line antihypertensive therapies from mechanistically distinct drug classes routinely used in contemporary primary care practice and hypertension guidelines. Doses were selected based on equivalent defined daily doses (DDD). The purpose of including multiple comparator therapies is to emulate real-world first-line prescribing practices in primary care rather than compare spironolactone against a single mechanistic alternative.
Comparator medications were selected because they represent common guideline-recommended first-line antihypertensive therapies from mechanistically distinct drug classes routinely used in contemporary primary care practice and hypertension guidelines. Doses were selected based on equivalent defined daily doses (DDD). The purpose of including multiple comparator therapies is to emulate real-world first-line prescribing practices in primary care rather than compare spironolactone against a single mechanistic alternative.
Comparator medications were selected because they represent common guideline-recommended first-line antihypertensive therapies from mechanistically distinct drug classes routinely used in contemporary primary care practice and hypertension guidelines. Doses were selected based on equivalent defined daily doses (DDD). The purpose of including multiple comparator therapies is to emulate real-world first-line prescribing practices in primary care rather than compare spironolactone against a single mechanistic alternative.
PRIMARY OUTCOME: Recruitment Rate of Randomized Participants per Month
Recruitment rate, defined as the average number of participants randomized per month during the recruitment period following activation of all participating study sites. Recruitment feasibility will be assessed by calculating the number of participants randomized each month over the 12-month recruitment period.
Time frame: 12 months following activation of all participating study sites
SECONDARY OUTCOME #1: Number of Potentially Eligible Participants Identified
Number of potentially eligible participants identified by participating primary care clinicians and referred for study screening.
Time frame: 12 months
SECONDARY OUTCOME #2: Eligibility Rate
Eligibility rate, defined as the proportion of screened participants who meet all study eligibility criteria. Calculated as the number of eligible participants divided by the number of screened participants.
Time frame: 12 months
SECONDARY OUTCOME #3: Recruitment Acceptance Rate
Recruitment acceptance rate, defined as the proportion of eligible participants who provide informed consent and undergo randomization. Calculated as the number of randomized participants divided by the number of eligible participants.
Time frame: 12 months
SECONDARY OUTCOME #4: Prevalence of Suppressed Renin Physiology
Proportion of screened participants with suppressed renin physiology, defined as a direct renin concentration \<6 ng/L (\<10 mU/L).
Time frame: 12 months
SECONDARY OUTCOME #5: Antihypertensive Washout Completion Rate
Proportion of participants for whom the protocol-specified antihypertensive washout procedures are successfully completed when applicable
Time frame: 12 months
SECONDARY OUTCOME #6: Ambulatory Blood Pressure Monitoring Completion Rate
Proportion of randomized participants who successfully complete ambulatory blood pressure monitoring (ABPM) according to the study protocol.
Time frame: 12 weeks
SECONDARY OUTCOME #7: Protocol Adherence Rate
Proportion of randomized participants completing assigned study treatment and the Week 12 outcome assessment procedures according to the study protocol.
Time frame: 12 weeks
SECONDARY OUTCOME #8: Study Completion Rate
Proportion of randomized participants completing the Week 12 end-of-study assessment.
Time frame: 12 weeks
SECONDARY OUTCOME #9: Reasons for Non-participation, Treatment Discontinuation, and Study Withdrawal
Frequency and categorized reasons for declining participation, treatment discontinuation, and withdrawal from the study.
Time frame: 12 months
SECONDARY OUTCOME #10: Data Completeness
Proportion of required study data fields completed without missing or invalid values.
Time frame: 12 weeks
SECONDARY OUTCOME #11: Primary Care Clinician Satisfaction With Patient Participation
Primary care clinician satisfaction with their patients' participation in the study, assessed using a post-study questionnaire.
Time frame: end of study (at 12 months)
SECONDARY OUTCOME #12: Primary Care Clinician Satisfaction With Study Communication
Primary care clinician satisfaction regarding communication on participant progress and handover of care following study completion, assessed using a post-study questionnaire.
Time frame: end of study (at 12 months)
SECONDARY OUTCOME #13: Primary Care Clinician Engagement
Proportion of participating primary care clinicians who continue referring potentially eligible participants throughout the study period.
Time frame: 12 months
Exploratory Outcome #1 (Blood pressure outcomes): Change in Mean Daytime Systolic Blood Pressure
Change in mean daytime systolic blood pressure measured by ambulatory blood pressure monitoring (ABPM) from baseline to Week 12.
Time frame: Baseline to Week 12
Exploratory Outcome #2 (Blood pressure outcomes): Change in Mean Daytime Diastolic Blood Pressure
Change in mean daytime diastolic blood pressure measured by ambulatory blood pressure monitoring (ABPM) from baseline to Week 12.
Time frame: Baseline to Week 12
Exploratory Outcome 3 (Blood pressure outcomes): Change in Mean 24-Hour Systolic Blood Pressure
Change in mean 24-hour systolic blood pressure measured by ambulatory blood pressure monitoring (ABPM) from baseline to Week 12.
Time frame: Baseline to Week 12
Exploratory Outcome 4 (Blood pressure outcomes): Change in Mean 24-Hour Diastolic Blood Pressure
Change in mean 24-hour diastolic blood pressure measured by ambulatory blood pressure monitoring (ABPM) from baseline to Week 12.
Time frame: Baseline to Week 12
Exploratory Outcome 5 (Blood pressure outcomes): Change in Standardized Office Systolic Blood Pressure
Change in standardized office systolic blood pressure from baseline to Week 12.
Time frame: Baseline to Week 12
Exploratory Outcome 6 (Blood pressure outcomes): Change in Standardized Office Diastolic Blood Pressure
Change in standardized office diastolic blood pressure from baseline to Week 12
Time frame: Baseline to Week 12
Exploratory Outcome 7 (Hypertension Control): Participants Achieving Daytime Ambulatory Blood Pressure Control
Proportion of participants achieving a mean daytime ambulatory systolic blood pressure \<130 mmHg at Week 12
Time frame: Week 12
Exploratory Outcome 8 (Hypertension Control): Participants Achieving Standardized Office Blood Pressure Control
Proportion of participants achieving a standardized office systolic blood pressure \<130 mmHg at Week 12
Time frame: Week 12
Exploratory Mechanistic Outcome #1: Change in Direct Renin Concentration
Change in direct renin concentration (ng/L) from baseline to Week 12
Time frame: Baseline to Week 12
Exploratory Mechanistic Outcome #2: Renin Unsuppression
Proportion of participants achieving renin unsuppression, defined as a direct renin concentration ≥6 ng/L (≥10 ng?L), at Week 12.
Time frame: week 12
Exploratory Mechanistic Outcome #3: Increase in Direct Renin Concentration
Proportion of participants demonstrating any increase in direct renin concentration from baseline to Week 12.
Time frame: Baseline to week 12
Exploratory Mechanistic Outcome #4: Association Between Renin Response and Blood Pressure Response
Association between the change in direct renin concentration and the change in mean daytime systolic blood pressure measured by ambulatory blood pressure monitoring from baseline to Week 12
Time frame: Baseline to Week 12
Safety Outcome #1: Symptomatic Hypotension
Proportion of participants experiencing symptomatic hypotension, including orthostatic symptoms, lightheadedness, injurious falls, or syncope.
Time frame: Baseline to Week 12
Safety Outcome #2: Hyperkalemia
Proportion of participants with serum potassium \>5.5 mmol/L
Time frame: Baseline to Week 12
Safety Outcome #3: Hypokalemia
Proportion of participants with serum potassium \<3.5 mmol/L.
Time frame: Baseline to Week 12
Safety Outcome #4: Change in Serum Potassium Concentration
Change in serum potassium concentration from baseline to Week 12
Time frame: Baseline to Week 12
Safety Outcome #5: ≥40% Decline in Estimated Glomerular Filtration Rate
Proportion of participants experiencing a ≥40% decline in estimated glomerular filtration rate (eGFR) from baseline.
Time frame: Baseline to Week 12
Safety Outcome #6: Dialysis Initiation
Proportion of participants initiating dialysis during the study period
Time frame: Baseline to Week 12
Safety Outcome #7: Hyponatremia
Proportion of participants with serum sodium \<135 mmol/L.
Time frame: Baseline to Week 12
Safety Outcome #8: Gynecomastia
Proportion of participants developing gynecomastia during the study period
Time frame: Baseline to Week 12
Safety Outcome #9: Medication Discontinuation Due to Adverse Events
Proportion of participants requiring medication discontinuation, dose reduction, or switching because of adverse events
Time frame: Baseline to Week 12
Safety Outcome #10: Major Adverse Cardiovascular Events
Proportion of participants experiencing myocardial infarction, stroke, heart failure hospitalization, peripheral arterial revascularization, or cardiovascular death
Time frame: Baseline to Week 12
Safety Outcome #11: All-Cause Hospitalization
Proportion of participants hospitalized for any cause.
Time frame: Baseline to week 12
Safety Outcome #12: All-Cause Mortality
Proportion of participants who die from any cause during the study period
Time frame: Baseline to Week 12
Plan to share: No
No publications or documents are linked to this record.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drug tested here: Spironolactone
Ottawa Hospital Research Institute →