Phentolamine is an alpha-adrenergic blocker used to treat hypertensive episodes, diagnose pheochromocytoma, treat norepinephrine administration site reactions, and reverse soft tissue anesthesia and mydriasis. Phentolamine is a reversible, non-selective alpha-adrenergic blocker that induces vasodilation.
- Mechanism
- Curator reviewed · 4 references
Phentolamine is a reversible, competitive antagonist at alpha-1 and alpha-2 adrenergic receptors. It causes vasodilation of vascular smooth muscles. Pupil dilation is primarily controlled by the radial iris dilator muscles surrounding the pupil, which are activated by the alpha-1 adrenergic receptors. Phentolamine reversibly binds to these receptors and reduces pupil diameter. By blocking alpha-1 adrenergic receptors, phentolamine can also be used to reverse mydriasis induced by muscarinic antagonists.
- Primary indication
- When used intravenously or intramuscularly, phentolamine is used to prevent or control hypertensive episodes that may occur in a patient with pheochromocytoma due to stress or manipulation during preoperative preparation and surgical excision.Curator reviewed · 8 structured indications
- Formula / weight
- C17H19N3O · 281.3523 g/mol (avg)
- First approval
- Canada, 2005 · United States, 1952
- Also known as
- 3-((4,5-DIHYDRO-1H-IMIDAZOL-2-YLMETHYL)(4-METHYLPHENYL)AMINO)PHENOL · Phentholamine
- Code names
- C 7337 · C 7337 Ciba
- Brand names
Resolves to
MRBDMNSDAVCSSF-UHFFFAOYSA-NSMILESCC1=CC=C(C=C1)N(CC1=NCCN1)C1=CC(O)=CC=C1What you can answer from here — as of September 23, 2026
Which drugs share a target with Phentolamine, and which of those have an active Phase 3 trial?
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