Baxdrostat, Lorundrostat: Aldosterone Synthase Inhibitors

Aldosterone synthase inhibitors are a new class of once-daily pills for blood pressure that stays high despite other medicines. The first, AstraZeneca’s baxdrostat (Baxfendy), was announced as FDA-approved on May 18, 2026. The second, Mineralys’ lorundrostat, has an FDA decision date of December 22, 2026. Together they are the main test of whether targeting aldosterone production, rather than blocking its receptor, can build a new hypertension category.

Mechanism at a glance

Both drugs block aldosterone synthase, the enzyme that makes aldosterone, a hormone involved in salt retention and blood pressure. Older mineralocorticoid-receptor blockers such as spironolactone act on the receptor instead. In the PATHWAY-2 trial, spironolactone lowered home systolic blood pressure by 8.70 mm Hg more than placebo in resistant hypertension, and 6 of 285 patients on it had potassium above 6.0 mmol/L at least once (Europe PMC). Different measurement methods make cross-trial comparisons unreliable.

Why it matters

In BaxHTN (796 patients, uncontrolled or resistant hypertension), 12-week placebo-adjusted reductions in seated systolic pressure were 8.7 mm Hg (1 mg) and 9.8 mm Hg (2 mg). Serum potassium above 6.0 mmol/L occurred in 2.3% and 3.0% of baxdrostat patients versus 0.4% on placebo (NEJM via Europe PMC). In Bax24 (published in The Lancet, March 2026), baxdrostat 2 mg lowered 24-hour ambulatory systolic pressure by 14.0 mm Hg versus placebo in resistant hypertension, with confirmed potassium above 6 mmol/L in 3 of 108 treated patients and none on placebo (Europe PMC). In Launch-HTN (1,083 patients, JAMA), lorundrostat 50 mg lowered week-6 office systolic pressure 9.1 mm Hg more than placebo; potassium above 6.0 mmol/L occurred in 1.1% versus 0.7% on placebo (JAMA). Potassium monitoring is the safety theme to track in both programs; for the wider hypertension trial picture see our trial activity overview.

Competitive pressure points

• First-mover versus follower: baxdrostat is approved in the US as an add-on for adults whose blood pressure is not controlled on other medicines, at 1 mg or 2 mg once daily (ACC). Lorundrostat’s application is under review (Mineralys 8-K).
• Company scale: AstraZeneca has said baxdrostat could reach $5 billion a year (pharmaphorum). Mineralys had $661.4 million in cash at June 30 and says it can fund launch into 2028.
• Setback for another ASI: Boehringer Ingelheim stopped the Phase 3 EASi-KIDNEY trial of vicadrostat plus empagliflozin in chronic kidney disease after a monitoring committee found no meaningful expected benefit; it was not a new safety signal, and three other EASi trials continue (HCPLive).
• Different mechanism: zilebesiran, an RNAi therapy from Roche and Alnylam, is in the ZENITH cardiovascular outcomes trial (about 11,000 patients, 300 mg every six months). Its Phase 2 KARDIA-3 study did not meet its pre-specified definition of statistical significance (Roche).

What to watch

• The FDA decision on lorundrostat and the labeling around potassium and kidney function.
• Whether baxdrostat is approved in the EU, where AstraZeneca’s February 2026 report listed a filing acceptance.
• Outcomes data: whether blood-pressure lowering by this route translates into fewer events.
• Read-through from EASi-KIDNEY to the remaining aldosterone-synthase programs in kidney and heart failure.

Recent developments

Updated November 4, 2026. Items are drawn from company announcements, regulators and trade press; links go to the sources.

• Sep 15, 2026: Boehringer Ingelheim discontinued EASi-KIDNEY (vicadrostat plus empagliflozin) on a data monitoring committee recommendation. (HCPLive)
• Aug 11, 2026: Mineralys reported the lorundrostat NDA under review with a PDUFA target date of December 22, 2026, and a $200.0 million upfront payment to Tanabe that eliminated royalty obligations. (Mineralys 8-K)
• May 18, 2026: AstraZeneca announced FDA approval of Baxfendy as the first aldosterone synthase inhibitor in the US. (TCTMD)
• Mar 2026: Bax24 published in The Lancet. (Europe PMC)
• Feb 10, 2026: AstraZeneca’s results reported BaxAsia data from December 2025 (2 mg met the primary endpoint) and listed baxdrostat filings in the US and EU as accepted. (AstraZeneca 6-K)

Upcoming catalysts

• Dec 22, 2026: FDA target action date for lorundrostat.

Bottom line

As of November 4, 2026, one aldosterone synthase inhibitor is approved in the US and a second faces a December decision. Efficacy looks consistent across programs, so the contest will likely turn on labeling, potassium management, outcomes evidence and payer access.

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This article is for informational and competitive-intelligence purposes only and is not medical advice. Approvals, labels and trial results change; verify details against current prescribing information and primary sources.