API Aprocitentan

Aprocitentan More Info

Aprocitentan is a novel, once-daily oral dual endothelin receptor antagonist (ERA) approved in 2024 for the management of resistant hypertension (rHTN) in adult patients. It is indicated as an add-on therapy for individuals whose blood pressure remains inadequately controlled despite treatment with a maximally tolerated three-drug regimen, including a diuretic.

Basic Information

Chemical Name: N-[5-(4-bromophenyl)-6-[2-[(5-bromo-2-pyrimidinyl)oxy]ethoxy]-4-pyrimidinyl]-sulfamide

Molecular Formula: C₁₆H₁₄Br₂N₆O₄S

Molecular Weight: Approximately 546.2 g/mol

CAS Number: 1038905-01-1

Physical Characteristics: White to off-white crystalline powder with poor water solubility; formulated as oral film-coated tablets in 12.5 mg and 25 mg strengths (25 mg variant is approved for use in the European Union).

Synonyms: ACT-132577; it is identified as the active metabolite of macitentan, another well-known endothelin receptor antagonist.

Mechanism of Action

Aprocitentan exerts its therapeutic effect by selectively blocking both endothelin A (ETA) and endothelin B (ETB) receptors, with a potency ratio of roughly 1:16 for ETA versus ETB. Endothelin-1 (ET-1) is a potent endogenous vasoconstrictor that contributes to vascular remodeling, fibrosis, and inflammation—key pathological processes driving resistant hypertension. By inhibiting ET-1 binding to its receptors, aprocitentan reduces vasoconstriction, improves vascular compliance, and promotes vasodilation through nitric oxide-mediated pathways. Notably, it undergoes minimal metabolism via the CYP450 enzyme system, resulting in a low potential for drug-drug interactions, which is advantageous for patients on multiple antihypertensive medications.

Pharmacokinetics

Absorption: Oral administration leads to peak plasma concentrations (Cmax) at approximately 4–5 hours post-dosing. Drug exposure is dose-proportional within the approved therapeutic range, and steady-state concentrations are achieved after 8 consecutive days of daily use. The absolute bioavailability of aprocitentan has not been fully determined.

Distribution: The compound is highly bound to plasma proteins (>99%), with a volume of distribution of about 20–40 L, indicating limited penetration into peripheral tissues.

Elimination: Aprocitentan is primarily eliminated via non-renal pathways; less than 10% of the administered dose is excreted unchanged in urine. The elimination half-life is approximately 24 hours, supporting its once-daily dosing schedule.

Safety and Precautions

Common Adverse Reactions: Peripheral edema is the most frequently reported side effect, followed by headache, nasopharyngitis, and fatigue. These reactions are generally mild to moderate in severity.

Contraindications: It is contraindicated in patients with hypersensitivity to aprocitentan or any of its excipients. Pregnant women are strictly prohibited from using this drug due to the risk of fetal developmental toxicity.

Special Populations: No dose adjustment is required for patients with mild to moderate renal or hepatic impairment. However, use in patients with severe renal or hepatic dysfunction is not recommended due to insufficient safety data. Close monitoring of blood pressure and edema is advised during the initial phase of treatment.