Parent study: A Study to Assess Efficacy and Safety of Baxdrostat in Participants with Primary Aldosteronism Sub-study: A Follow-up Substudy After Completion of the BaxPA Main Study. - BaxPA

Inclusion Criteria

• Parent study
• Inclusion Criteria:
• - Male or female participants must be ≥ 18 years of age
• - Participants with a documented diagnosis of PA that fulfils the criteria defined in the 2016 or 2025 Endocrine Society Guidelines.
• - Participants willing and able to cease dosing of MRA or potassium sparing diuretics per study requirement for participants taking an MRA or potassium sparing diuretic at Screening.
• - eGFR ≥ 45 mL/min/1.73m2 at Screening
• - Serum potassium level ≥ 3.0 and < 5.0 mmol/L at Screening determined as per the central laboratory.
• - Have a stable regimen of antihypertensive medications for at least 4 weeks prior to randomisation
• - Mean seated SBP on AOBPM of ≥ 135 mmHg and ≤ 170 mmHg and mean DBP of
• ≤ 105 mmHg.
• - Serum potassium (local lab) > 3.0 mmol/L at randomization.
• Exclusion Criteria:
• - If not taking an MRA or potassium sparing diuretic at Screening: Mean seated SBP > 170 mmHg or mean seated DBP >105 mmHg (on AOBPM).
• If taking an MRA or potassium sparing diuretic at Screening: Mean seated SBP > 160 mmHg or mean seated DBP ≥ 100 mmHg.
• - Previous surgical intervention for an adrenal adenoma or have a planned adrenalectomy, renal nerve denervation, or adrenal ablative procedure during the course of the study.
• - Has the following known secondary causes of HTN: renal artery stenosis, uncontrolled or untreated hyperthyroidism, uncontrolled or untreated hypothyroidism, pheochromocytoma, Cushing’s syndrome, aortic coarctation.
• - Serum sodium level < 135 mmol/L at Screening, determined as per central laboratory.
• - New York Heart Association functional HF class IV at Screening.
• - Persistent atrial fibrillation.
• - Treatment with any MRA or potassium-sparing diuretic within 2 weeks prior to Randomisation.
• Substudy
• Inclusion Criteria:
• Completed the BaxPA main study through the End of Study visit and was randomised and treated during the Randomised Withdrawal period.
• Exclusion Criteria:
• Not applicable