- Hydroxyamphetamine is a pharmacological agent that stimulates the release of norepinephrine from nerve endings, leading to pupil dilation (mydriasis).
- It is commonly used in combination with tropicamide (as in the formulation Paremyd) to differentiate between preganglionic and postganglionic lesions in Horner’s syndrome.
Chemical Structure & Formula
- Chemical Formula: C₉H₁₃NO
- Structure:
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Mechanism of Action (Detailed)
- Increases norepinephrine release from presynaptic neurons → More stimulation of α and β receptors.
- Weak MAO inhibitor → Prevents norepinephrine degradation, prolonging effects.
- No direct receptor activation, effects are mediated via endogenous catecholamines.
Physiological Effects
-
Cardiovascular:
- Increases blood pressure (α1-mediated vasoconstriction).
- Increases heart rate (β1 activation via norepinephrine release).
-
CNS:
- Mild stimulant effects (but weaker than amphetamine).
-
Ocular:
- Mydriasis (pupil dilation) by stimulating norepinephrine release in the iris.
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Side Effects of Hydroxyamphetamine
- Tachycardia & Arrhythmias
- Hypertension
- Insomnia & Nervousness
- Dry mouth & Urinary retention (due to sympathetic overactivity)
Clinical Uses of Hydroxyamphetamine
- Pupil dilation (diagnostic use) → Used in Horner’s syndrome test to differentiate between central and peripheral lesions.
- Rarely used as a CNS stimulant.
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