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  • Product NameMinoxidil
  • Molecular FormulaC9H15N5O
  • Purity99%
  • AppearanceWhite crystalline powder

Product Details

Quick Details

  • CasNo: 38304-91-5
  • Molecular Formula: C9H15N5O
  • Appearance: White crystalline powder
  • Purity: 99%

38304-91-5 Properties

  • Molecular Formula:C9H15N5O
  • Molecular Weight:209.251
  • Appearance/Colour:White crystalline powder 
  • Vapor Pressure:0mmHg at 25°C 
  • Melting Point:272-274 °C (dec.)(lit.) 
  • Refractive Index:1.724 
  • Boiling Point:351.7 °C at 760 mmHg 
  • PKA:4.61(at 25℃) 
  • Flash Point:166.5 °C 
  • PSA:91.16000 
  • Density:1.52 g/cm3 
  • LogP:0.91830 

38304-91-5 Usage

an antihypertensive vasodilator medication

38304-91-5 is an antihypertensive vasodilator medication also claiming to slow or stop hair loss and promote hair regrowth. It is available over the counter for treatment of androgenic alopecia, among other baldness treatments, but measurable changes, if experienced, disappear within months after discontinuation of treatment.38304-91-5 was first sold as a drug for high blood pressure and was noted to have the interesting side-effect of increased body hair-growth, or in some cases, significant hair loss. Treatments for baldness and hair loss usually include a 5% concentration solution that is designed for men, whereas the 2% concentration solutions are designed for women.

Indications and Usage

38304-91-5 is a type of oral drug that is clinically used to lower blood pressure, and it is also called Loniten and piperidine diamine. 38304-91-5 is an antihypertensive drug that is clinically used to treat intractable, primary or renal hypertension. It can also be used to treat severe hypertension that does not respond well to other antihypertensive drugs, but it needs to be used in combination with diuretic drugs to prevent water and sodium retention, and combined use with beta receptor blockers may increase its curative effects and reduce adverse effects. 38304-91-5 is also used to prevent grease-type alopecia and on livestock.

Mechanisms of Action

38304-91-5 is a type of potassium channel opener and can directly relax smooth vascular muscles and has a strong small artery dilating effect. It can reduce peripheral resistance, dilate blood vessels, and lower blood pressure while having no effect on blood volume, thus promoting venous return. In addition, due to reflective regulation and positive frequency effects, it can increase cardiac output and heart rate, but will not cause orthostatic hypotension.

Adverse reactions

Long term use of 38304-91-5 may have the side effect of increased body hair, such as arm hair. Adverse reactions to oral intake mainly include: weight gain and lower body swelling due to water and sodium retention, heart palpitations and arrhythmia due to reflexive sympathetic nervous excitement, and hirsuitism. Adverse reactions to external use mainly include: skin irritation, red spots in applied areas, itching, and other skin inflammation reactions. Although only a small amount is absorbed, but there is also a slight possibility of causing a recurrence in patients with a history or heart disease. Use with caution if suffering from cerebrovascular disease, non-hypertensive heart failure, coronary heart disease, angina pectoris, myocardial infarction, pericardial effusion, renal dysfunction and other diseases.


Do not use if allergic to 38304-91-5 or suffering from pheochromocytoma.


38304-91-5 is a peripheral vasodilator that directly relaxes vascular smooth musculature, thus, lowering systolic and diastolic pressure. Its action is linked to the activation of calcium channels. Open calcium channels cause hyperpolarization of smooth muscle cells, which in turn, reduces the flow of calcium ions into the cell, which is necessary for supporting vascular tonicity. However, when taking minoxidil, tachycardia, elevated renin secretion, and water and sodium ion retention all appear simultaneously with hypotension.

Chemical Properties

White Crystalline Solid


Loniten ,Upjohn ,US ,1979


Used as an antihypertensive and antialopecia agent. 38304-91-5 activates ATP-activated K+ channels


antihypertensive, antialopecia agent


A selective ATP dependent K+ (Kir6) channel activator


ChEBI: A pyrimidine N-oxide that is pyrimidine-2,4-diamine 3-oxide substituted by a piperidin-1-yl group at position 6.

Manufacturing Process

Barbituric acid is reacted with phosphorus oxychloride then with 2,4,6-trichloropyrimidine and that product with ammonia to give 4-chloro-2,6-diaminopyritnidine.A 30 g (0.15 mol) quantity of 4-chloro-2,6-diaminopyrimidine is dissolved in600 ml of hot 3A alcohol, the solution cooled to 0°C to 10°C and 41.8 g (0.24mol) of m-chloroperbenzoic acid is added. The mixture is held at 0°C to 10°Cfor 4 hours and filtered. The solid is shaken for 2 hours in 0.24 mol of 10%sodium hydroxide and filtered. The solid is washed with water and dried toyield 193 g of crude product. This product is extracted for 1 hour with 900 mlof boiling acetonitrile to yield 14.8 g (44.7% yield) of 6-amino-4-chloro-1,2-dihydro-1-hydroxy-2-iminopyrimidine, melting point 193°C.A mixture of 3.0 g (0.019 mol) of 6-amino-4-chloro-1,2-dihydro-1-hydroxy-2-iminopyrimidine and 35 ml of piperidine is refluxed for 1.5 hours, cooled andfiltered. The solid is shaken for 20 minutes in a solution of 0.8 g of sodiumhydroxide in 30 ml of water and filtered. The solid is washed with water andextracted with 800 ml of boiling acetonitrile and filtered to yield 3.5 g (89%)yield of 6-amino-4-chloro-1,2-dihydro-1-hydroxy-2-iminopyrimidine, meltingpoint 248°C, decomposition at 259°C to 261°C.

Brand name

Loniten (Pharmacia & Upjohn); Rogaine (Pharmacia & Upjohn); Minodyl (Quantum Pharmics).

Therapeutic Function


General Description

38304-91-5, 2,4-diamino-6-piperidinopyrimidine-3-oxide . It is converted to minoxidil sulfate in the liver bya sulfotransferase enzyme.The antihypertensive properties of minoxidil are similarto those of hydralazine hydrochloride, in that minoxidil candecrease arteriolar vascular resistance. 38304-91-5 exerts itsvasodilatory action by a direct effect on arteriolar smoothmuscle and appears to have no effect on the CNS or on theadrenergic nervous system in animals. The serum half-lifeis 4.5 hours, and the antihypertensive effect may last up to24 hours.

Biological Activity

Antihypertensive. Antialopecia agent. K + channel (K ATP ) activator.

Biochem/physiol Actions

Activates ATP-activated K+ channels; vasodilator; slow or stop hair loss and promote hair regrowth.

Mechanism of action

Potassium channel openers are drugs that activate (i.e., open) ATP-sensitive K+ channels in the VSM. By opening these potassium channels, there is increased efflux of potassium ions from the cells, causing hyperpolarization of VSM, which closes the voltage-gated calcium channels and, thereby, decreases intracellular calcium. With less calcium available to combine with calmodulin, there is less activation of MLCK and phosphorylation of myosin light chains. This leads to relaxation and vasodilation. Because small arteries and arterioles normally have a high degree of smooth muscle tone, these drugs are particularly effective in dilating these resistance vessels, decreasing systemic vascular resistance, and lowering arterial pressure. The fall in arterial pressure leads to reflex cardiac stimulation (baroreceptor-mediated tachycardia). 38304-91-5, as its active metabolite minoxidil O-sulfate, prolongs the opening of the potassium channel, sustaining greater vasodilation on arterioles than on veins. The drug decreases blood pressure in both the supine and standing positions, and there is no orthostatic hypotension. Associated with the decrease in peripheral resistance and blood pressure is a reflex response that is accompanied by increased heart rate, cardiac output, and stroke volume, which can be attenuated by the coadministration of a β-blocker. Along with this decrease in peripheral resistance is increased plasma renin activity and sodium and water retention, which can result in expansion of fluid volume, edema, and congestive heart failure. The sodium- and water-retaining effects of minoxidil can be reversed by coadministration of a diuretic. When minoxidil is used in conjunction with a β-adrenergic blocker, pulmonary artery pressure remains essentially unchanged.


38304-91-5 is absorbed from the GI tract and is metabolized to its active sulfate metabolite. Plasma concentrations for minoxidil sulfate peak within 1 hour and then decline rapidly. Following an oral dose of minoxidil, its hypotensive effect begins in 30 minutes, is maximal in 2 to 8 hours, and persists for approximately 2 to 5 days. The delayed onset of the hypotensive effect for minoxidil is attributed to its metabolism to its active metabolite. The drug is not bound to plasma proteins. The major metabolite for minoxidil is its N-O-glucuronide, which unlike the sulfate metabolite is inactive as a hypotensive agent. Approximately 10 to 20% of an oral dose of minoxidil is metabolized to its active metabolite, minoxidil O-sulfate, and approximately 20% of minoxidil is excreted unchanged.

Clinical Use

38304-91-5 is used for severe hypertension that is difficultto control with other antihypertensive agents. The drug hassome of the characteristic side effects of direct vasodilatorydrugs. It causes sodium and water retention and may requirecoadministration of a diuretic. 38304-91-5 also causes reflextachycardia, which can be controlled by use of a -adrenergicblocking agent.38304-91-5 topical solution is used to treat alopecia androgenitica(male-pattern baldness). Although the mechanismis not clearly understood, topical minoxidil is believed to increasecutaneous blood flow, which may stimulate hairgrowth. The stimulation of hair growth is attributed to vasodilationin the vicinity of application of the drug, resultingin better nourishment of the local hair follicles.

Side effects

Adverse reactions include local irritation and contact dermatitis. If the treatment is discontinued, clinical regression occurs within 3 months to the state of hair thinning that would have occurred had the treatment not been started. Twice-daily treatment is more efficacious than once-daily application. Women who use the5%concentrationmay note the development of facial hair, which is reversible on discontinuation of the medication. The 5% concentration can be more irritating than the 2% solution.


38304-91-5, 6-amino-1,2-dihydro-1-hydroxy-2-imino-4-piperidinopyrimidine (22.8.5), is synthesized from barbituric acid, the reaction of which with phosphorous oxychloride gives 2,4,6-trichloropyrimidine (22.8.1). Upon reaction with ammonium, this turns into 2,4-diamino-6-chloropyrimidine (22.8.2). Next, the resulting 2,4-diamino-6- chloropyrimidine (22.8.2) undergoes reaction with 2,4-dichlorophenol in the presence of potassium hydroxide, giving 2,4-diamino-6-(2,4-dichlorophenoxy)-pyrimidine (22.8.3). Oxidation of this product with 3-chloroperbenzoic acid gives 2,4-diamino-6-(2,4- dichlorophenoxy)pyrimidine-3-oxide (22.8.4), the 2,4-dichlorophenoxyl group of which is replaced with a piperidine group at high temperature, giving minoxidil (22.8.5).

Drug interactions

When minoxidil is administered with diuretics or other hypotensive drugs, the hypotensive effect of minoxidil increases, and concurrent use may cause profound orthostatic hypotensive effects.


Extensively metabolised by the liver. It requires sulphation to become active, but the major metabolite is a glucuronide conjugate. Excreted mainly in the urine in the form of metabolites. 38304-91-5 and its metabolites are dialysable, although the pharmacological effect is not reversed.


1) Meisheri et al. (1988), Mechanism of action of minoxidil sulfate-induced vasodilation: a role for increased K+ permeability; J. Pharmacol. Exp. Ther., 245 7 2) Messenger and Rundegren (2004) 38304-91-5:mechanisms of action on hair growth; Br. J. Dermatol., 150 186


38304-91-5 Relevant articles

The promoted synthesis of minoxidil by magnetic nanoparticles of cobalt ferrite (CoFe2O4) as a heterogeneous reusable catalyst

Eisavi, Ronak,Ahmadi, Fatemeh,Zeynizadeh, Behzad,Kouhkan, Mehri

, p. 1425 - 1435 (2019/11/02)

38304-91-5 (2,4-diamino-6-piperidinopyrimidine 3-oxide) was primarily recognized as a drug for reducing vascular resistance to blood flow. It was later introduced as a more important medicine for topical stimulation of hair growth and baldness reverting as well as treatment of androgenic alopecia through increasing prostaglandin endoperoxide synthesis. In this study, magnetic nanoparticles (MNPs) of spinel ferrites (MFe 2 O 4, M = Co, Ni, Fe, Cu, and Zn) via solid-state grinding procedure were prepared and then characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer, and Fourier transform infrared techniques. The prepared nanoferrites were utilized as efficient and green heterogeneous catalysts for N -oxidation of 2,6-diamino-4-chloro-pyrimidine with H 2 O 2 in refluxing ethanol giving 2,6-diamino-4-chloro-pyrimidine N -oxide as a starting material for the synthesis of 2,4-diamino-6-piperidinopyrimidine 3-oxide (minoxidil). Among the examined nanoferrites, CoFe 2 O 4 MNPs exhibited prominent catalytic activity giving the product in 95% yield within 60 min. Moreover, the reusability of nano-CoFe 2 O 4 was examined for 6 consecutive cycles without significant loss of catalytic activity and magnetic property.

Nanoparticles comprising half esters of poly (methyl vinyl ether-co-maleic anhydride) and uses thereof


, (2012/11/06)

The present invention relates to nanoparticles for encapsulating compounds, the preparation and uses thereof, said nanoparticles being based on half (C1-C4) alkyl esters of poly (methyl vinyl ether-co-maleic anhydride) (PVM/MA) copolymers. Said nanoparticles can encapsulate or incorporate a product of interest. For use in the agricultural, cosmetic, food or pharmaceutical fields.



, (2012/12/13)

Methods and compositions for stimulating the growth of hair are disclosed wherein said compositions include bimatoprost and minoxidil in a vehicle for topical application to the skin of a mammal, e.g. a human, whereby the combination of bimatoprost and minoxidil produces a faster onset of hair growth in humans or other mammals and wherein said composition brings about a synergestic result of faster onset of hair growth as compared to compositions comprising bimatoprost and minoxidil, alone.

3-deoxyglucosone and skin


, (2008/06/13)

The invention relates to a method of removing 3-deoxyglucosone and other alpha-dicarbonyl sugars from skin. The invention further relates to methods of inhibiting production and function of 3-deoxyglucosone and other alpha-dicarbonyl sugars in skin. The invention also relates to methods of treating 3-deoxyglucosone and other alpha-dicarbonyl sugars associated diseases and disorders of skin.

38304-91-5 Process route

2,6-diamino-4-chloro-pyrimidine N-oxide

2,6-diamino-4-chloro-pyrimidine N-oxide

2,4-diamino-6-piperidinopyrimidine 3-oxide

2,4-diamino-6-piperidinopyrimidine 3-oxide

Conditions Yield
at 106 ℃; for 2h;


2,4-diamino-6-piperidinopyrimidine 3-oxide

2,4-diamino-6-piperidinopyrimidine 3-oxide

Conditions Yield

38304-91-5 Upstream products

  • 110-89-4


  • 35139-67-4

    2,6-diamino-4-chloro-pyrimidine N-oxide

  • 65277-42-1



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