Minoxidil
[CAS# 38304-91-5]

Identification

• Classification: API >> Circulatory system medication >> Prevention and treatment of angina pectoris
• Name: Minoxidil
• Synonyms: 2,4-Diamino-6-piperidino-pyrimidine-3-oxide; 6-(1-Piperidinyl)-2,4-pyrimidinediamine-3-oxide; Loniten; Regain; Rogaine
• Molecular Formula: C₉H₁₅N₅O
• Molecular Weight: 209.25
• CAS Registry Number: 38304-91-5 (16317-69-4)
• EC Number: 253-874-2
• SMILES: C1CCN(CC1)C2=NC(=N)N(C(=C2)N)O

Properties

• Solubility: 2.295e+004 mg/L (25 °C water)
• Density: 1.5±0.1 g/cm³, Calc.^*
• Index of Refraction: 1.724, Calc.^*
• Melting point: 177.26 °C
• Boiling Point: 351.7±45.0 °C (760 mmHg), Calc.^*, 424.35 °C
• Flash Point: 166.5±28.7 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H332-H335
• Safety Statements: P261-P280-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Reproductive toxicity	Repr.	2	H361
Carcinogenicity	Carc.	2	H351
Reproductive toxicity	Repr.	2	H361d
Specific target organ toxicity - single exposure	STOT SE	3	H336

Discovery and Applications

Originally developed in the 1950s as an oral medication for the treatment of ulcers, researchers serendipitously discovered Minoxidil's unexpected side effect of promoting hair growth. This unexpected finding led to extensive research into the compound's mechanism of action and its potential application in addressing hair loss disorders. In the late 1970s, Minoxidil was repurposed as a topical solution for the treatment of androgenetic alopecia, commonly known as male and female pattern baldness.

Minoxidil is widely used as a topical treatment for androgenetic alopecia in both men and women. Applied directly to the scalp, it stimulates hair follicles, prolongs the growth phase of the hair cycle, and increases hair density and thickness, leading to visible regrowth of hair in affected areas. Minoxidil has shown efficacy in the treatment of alopecia areata, an autoimmune condition characterized by patchy hair loss. Although its precise mechanism in alopecia areata is not fully understood, Minoxidil's ability to promote hair growth makes it a valuable therapeutic option for individuals with this condition. Following childbirth, many women experience temporary hair shedding known as postpartum telogen effluvium. Minoxidil can help accelerate the regrowth of hair and restore hair density in women experiencing postpartum hair loss. Minoxidil has gained popularity as an off-label treatment for stimulating beard growth in individuals with sparse or patchy facial hair. Minoxidil may also be used to treat other scalp conditions such as telogen effluvium, scalp psoriasis, and seborrheic dermatitis, where hair loss or thinning is a prominent feature. Its ability to promote hair regrowth and improve scalp health makes it a versatile therapeutic option for various scalp disorders.

References

2024. The History of Hair Loss Treatments. Updates in Clinical Dermatology.
DOI: 10.1007/978-3-031-74314-6_1

1984. Determination of Minoxidil in Bulk Drug and Pharmaceutical Formulations by Ion-Pairing High-Performance Liquid Chromatography. Journal of Pharmaceutical Sciences, 73(9).
DOI: 10.1002/jps.2600730926

1987. Sulfation of minoxidil by human platelet sulfotransferase. Clinica chimica acta; international journal of clinical chemistry, 171(2-3).
DOI: 10.1016/0009-8981(87)90322-6