Minoxidil is a chemical compound, is a pyrimidine-N oxide.

It appears in the form of a colourless, stable clear liquid, incompatible with oxidising agents, acids and bases.

What it is used for and where

Medical

Minoxidil is an orally or topically administered vasodilator and was first used in 1970 for the treatment of severe hypertension and, by chance, a team of doctors noticed hypertrichosis and hair growth in patients taking 2% minoxidil. In 1993, a 2% solution of minoxidil for the treatment of female androgenetic alopecia and a 5% solution for the treatment of male androgenetic alopecia was placed on the market after approval by the US Food and Drug Administration (FDA) in 1988. 

It also improves the growth of eyebrows, beard and body hair. It is metabolised in the liver by glucuronic acid. The mechanism underlying the hair-growth effects of minoxidil is not yet fully elucidated as, alongside the vasodilating action, there is the opening of the potassium channel, which causes hyperpolarisation of cell membranes (1) increasing the size of the hair follicle. 

Minoxidil is also used as a 2% or 5% topical solution to be applied locally.

Currently (2019) only topical minoxidil and oral finasteride have received FDA and EMA (European Medicines Agency) approval for the treatment of androgenetic alopecia (AGA). Recently (2021), Japan and South Korea approved oral dutasteride (0.5 mg/day) for male AGA.

Safety

Although oral intake of minoxidil at 2% or 5% is generally considered safe, in some cases it has been associated with morning periorbital oedema (2), hypomethosis. Higher doses have been associated with pedal oedema in 2% of patients, heart rate alterations in 1.3% and postural hypotension in 1.1% (3).

Minoxidil studies

Caratteristiche tipiche del prodotto commerciale Minoxidil

Appearance	Clear colorless liquid
pH	8.6
Boiling Point	351.7±45.0°C at 760 mmHg
Melting Point	272-274°C
Flash Point	166.5±28.7°C    40.6C (105°F)
Density	1.5±0.1 g/cm3
PSA	91.16000
LogP	-1.49
Refraction Index	1.724
Vapor Pressure	0.0±1.8 mmHg at 25°C   59.3 mmHg@25°C (Ethanol)
Vapor Density	1.59 (Ethanol)
Flammable limits	LEL 3%
UEL	19%
Safety

Price   

25 mg  €99,40

500 mg  € 1.020,00

• Molecular Formula    C₉H₁₅N₅O
• Molecular Weight     209.25
• Exact Mass    209.127655
• CAS    38304-91-5
• UNII    5965120SH1
• EC Number   253-874-2
• DSSTox Substance ID  DTXSID9040685
• IUPAC  3-hydroxy-2-imino-6-piperidin-1-ylpyrimidin-4-amine
• InChI=1S/C9H15N5O/c10-7-6-8(12-9(11)14(7)15)13-4-2-1-3-5-13/h6,11,15H,1-5,10H2  
• InChl Key      ZIMGGGWCDYVHOY-UHFFFAOYSA-N
• SMILES   C1CCN(CC1)C2=NC(=N)N(C(=C2)N)O
• MDL number  MFCD00063409
• PubChem Substance ID    24277853
• ChEBI  6942
• NCI    C47623
• RXCUI       6984
• NSC   757106
• RTECS   UV8200000
• NACRES NA.77  

Synonyms

• 6-(1-Piperidinyl)pyrimidine-2,4-diamine 3-oxide
• 6-(1-Piperidinyl)-2,4-pyrimidinediamine 3-oxide
• 2,4-Pyrimidinediamine, 6-(1-piperidinyl)-, 3-oxide
• 3-hydroxy-2-imino-6-piperidin-1-ylpyrimidin-4-amine
• Regaine
• Loniten
• Alostil
• Rogaine
• Minodyl
• Minoximen
• Prexidil
• Alopexil
• Apo-Gain
• Theroxidil

References______________________________________________________________________

(1) Rossi A, Cantisani C, Melis L, Iorio A, Scali E, Calvieri S. Minoxidil use in dermatology, side effects and recent patents. Recent Pat Inflamm Allergy Drug Discov. 2012 May;6(2):130-6. doi: 10.2174/187221312800166859.

(2) Mir-Bonafé JF, Mir-Bonafé M, Rozas-Muñoz E, Mir-Bonafé JM. Morning Periorbital Edema Related to Low-Dose Oral Minoxidil. Actas Dermosifiliogr. 2022 Apr 28:S0001-7310(22)00298-8. English, Spanish. doi: 10.1016/j.ad.2021.09.010. 

(3) Jimenez-Cauhe J, Saceda-Corralo D, Rodrigues-Barata R, Moreno-Arrones OM, Ortega-Quijano D, Fernandez-Nieto D, Jaen-Olasolo P, Vaño-Galvan S. Safety of low-dose oral minoxidil treatment for hair loss. A systematic review and pooled-analysis of individual patient data. Dermatol Ther. 2020 Nov;33(6):e14106. doi: 10.1111/dth.14106.