Minoxidil sulfate
Minoxidil sulfate.svg
Clinical data
Other namesMinoxidil sulphate; Minoxidil sulfate ester; Minoxidil sulphate ester; Minoxidil N-O-sulfate; Minoxidil N-O-sulphate; U-58838
  • (2,6-diamino-4-piperidin-1-ylpyrimidin-1-ium-1-yl) sulfate
CAS Number
PubChem CID
ECHA InfoCard100.163.834 Edit this at Wikidata
Chemical and physical data
Molar mass289.31 g·mol−1
3D model (JSmol)
  • C1CCN(CC1)C2=NC(=[N+](C(=C2)N)OS(=O)(=O)[O-])N
  • InChI=1S/C9H15N5O4S/c10-7-6-8(13-4-2-1-3-5-13)12-9(11)14(7)18-19(15,16)17/h6H,1-5H2,(H4,10,11,12,15,16,17)

Minoxidil sulfate, also known as minoxidil sulfate ester or minoxidil N-O-sulfate, is an active metabolite of minoxidil (Rogaine, Loniten, others) and is the active form of this agent.[1][2] Minoxidil acts as a prodrug of minoxidil sulfate.[1] Minoxidil sulfate is formed from minoxidil via sulfotransferase enzymes, with the predominant enzyme responsible, at least in hair follicles, being SULT1A1.[1][2] Minoxidil sulfate acts as a potassium channel opener, among other actions, and has vasodilating, hypotensive, and trichogenic or hypertrichotic (hair growth-promoting) effects.[1][3] Its mechanism of action in terms of hair growth is still unknown, although multiple potential mechanisms have been implicated.[1]

Minoxidil sulfate is a sulfate ester of minoxidil, not a sulfate salt of the compound.[3] However, minoxidil sulfate forms an inner salt, which makes it more hydrophobic than minoxidil.[3] This is in contrast to most sulfate esters, which are usually more hydrophilic than their non-ester forms.[3] The bioactivation of minoxidil into minoxidil sulfate is very unusual and is among the only known instances of sulfation producing a more active drug form.[3][4] Normally, sulfation tends to inactivate drugs by reducing their biological activity and increasing their excretion.[3][4]

Minoxidil sulfate is highly unstable in aqueous solutions and alcohol-containing solvents, with a half-life of 6 hours in aqueous solutions and a further much lower half-life in alcohol-containing solvents.[3] This has served as a limiting factor in its potential pharmaceutical use and therapeutic effectiveness.[5] Moreover, minoxidil sulfate has a 40% higher molecular weight than minoxidil, and this may reduce its absorption into the scalp.[5] In any case, a minoxidil sulfate-based topical formulation has been investigated for the treatment of scalp hair loss.[6][5] Additionally, minoxidil-sulfate-based topical formulations appear to be available for medical use in some parts of the world, for instance in Brazil.[5][7]


  1. ^ a b c d e Gupta AK, Talukder M, Venkataraman M, Bamimore MA (June 2022). "Minoxidil: a comprehensive review". J Dermatolog Treat. 33 (4): 1896–1906. doi:10.1080/09546634.2021.1945527. PMID 34159872. S2CID 235609487.
  2. ^ a b Villani A, Fabbrocini G, Ocampo-Candiani J, Ruggiero A, Ocampo-Garza SS (July 2021). "Review of oral minoxidil as treatment of hair disorders: in search of the perfect dose". J Eur Acad Dermatol Venereol. 35 (7): 1485–1492. doi:10.1111/jdv.17216. PMID 33660357. S2CID 232115094.
  3. ^ a b c d e f g Meisheri KD, Johnson GA, Puddington L (January 1993). "Enzymatic and non-enzymatic sulfation mechanisms in the biological actions of minoxidil". Biochem Pharmacol. 45 (2): 271–9. doi:10.1016/0006-2952(93)90061-z. PMID 8435087.
  4. ^ a b Richard B. Silverman (2 December 2012). The Organic Chemistry of Drug Design and Drug Action (2 ed.). Elsevier. pp. 543–. ISBN 978-0-08-051337-9. OCLC 1019583017.
  5. ^ a b c d Dias PC, Miot HA, Trüeb RM, Ramos PM (October 2018). "Use of Minoxidil Sulfate versus Minoxidil Base in Androgenetic Alopecia Treatment: Friend or Foe?". Skin Appendage Disord. 4 (4): 349–350. doi:10.1159/000488011. PMC 6219241. PMID 30410915.
  6. ^ Suchonwanit P, Thammarucha S, Leerunyakul K (2019). "Minoxidil and its use in hair disorders: a review". Drug Des Devel Ther. 13: 2777–2786. doi:10.2147/DDDT.S214907. PMC 6691938. PMID 31496654.
  7. ^ Kelly, Yanna; Tosti, Antonella (13 September 2019). "Androgenetic Alopecia: Clinical Treatment". Hair and Scalp Treatments. Springer International Publishing. pp. 91–108. doi:10.1007/978-3-030-21555-2_8.