Minoxidil

Minoxidil is an antihypertensive vasodilator medication and a hair growth promoter used for the treatment of androgenic alopecia (male and female pattern hair loss). As a potent direct-acting peripheral vasodilator, Minoxidil reduces peripheral resistance and produces a fall in blood pressure. Minoxidil is metabolized by sulfation to the active compound, minoxidil sulfate, which acts as an opener of vascular smooth muscle ATP-dependent K⁺ (KATP) channels. Minoxidil is available over-the-counter for topical application in the treatment of hair loss, and is also used as an antihypertensive agent for refractory, primary, or renal hypertension. In quality control contexts, Minoxidil is supplied as a high-purity reference standard for analytical method development and quality control applications. Minoxidil is a white crystalline solid with a melting point of 272–274 °C (dec.), and is stored at 2–8 °C or at room temperature in a cool, dark place under inert gas.

 

Product Parameters

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Parameter	Specification
Product Name	Minoxidil
CAS Number	38304-91-5
Molecular Formula	C₉H₁₅N₅O
Molecular Weight	209.25 g/mol
Physical Form	Solid
Appearance	White to almost white powder to crystal
Melting Point	272–274 °C (dec.)
Boiling Point	348.61 °C (rough estimate)
Density	1.1651 (rough estimate)
pKa	4.61 (at 25 °C)
Storage Condition	2–8 °C

Pharmacological Action

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Minoxidil directly dilates small arteries, thereby exerting antihypertensive effects, although the exact mechanism remains unclear. This agent does not dilate small veins. Reduction in peripheral vascular resistance leads to a reflexive increase in heart rate and cardiac output. Following blood pressure reduction, renin activity rises, resulting in water and sodium retention. Minoxidil does not interfere with the vasomotor reflex, thus preventing orthostatic hypotension. It is a commonly used and effective medication for alopecia treatment; however, its pharmacological mechanisms and target cells remain poorly understood.

 

Side effect

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Common adverse effects include local skin irritation reactions such as dryness, desquamation, pruritus, erythema, and hypertrichosis. These predominantly occur on the face, neck, upper limbs, and lower extremities. Other side effects may include tachycardia and allergic reactions, though the latter occurs in less than 5% of cases and resolves upon discontinuation of treatment; thus, there is no need for excessive concern.

 

Synthetic Route

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4-Chloro-2,6-diaminopyrimidine was obtained by cyclization and chlorination of methyl cyanoacetate (see 08910), followed by an oxidative reaction with benzoic acid to yield 6-amino-1,2-dihydro-1-hydroxy-2-imino-4-chloropyrimidine (C4H5CIN4O), which was ultimately condensed with hexahydropyridine to produce minacalcidine.

 

Contact Us

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Ready to source Minoxidil for your antihypertensive API manufacturing, hair growth product development, or analytical reference standard needs? Cosperpharm is your trusted partner.