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2D Structure
Also known as: 38304-91-5, Rogaine, Loniten, Minoximen, Regaine, Theroxidil
Molecular Formula
C9H15N5O
Molecular Weight
209.25  g/mol
InChI Key
ZIMGGGWCDYVHOY-UHFFFAOYSA-N
FDA UNII
5965120SH1

A potent direct-acting peripheral vasodilator (VASODILATOR AGENTS) that reduces peripheral resistance and produces a fall in BLOOD PRESSURE. (From Martindale, The Extra Pharmacopoeia, 30th ed, p371)
Minoxidil is an Arteriolar Vasodilator. The physiologic effect of minoxidil is by means of Arteriolar Vasodilation.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
3-hydroxy-2-imino-6-piperidin-1-ylpyrimidin-4-amine
2.1.2 InChI
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
2.1.3 InChI Key
ZIMGGGWCDYVHOY-UHFFFAOYSA-N
2.1.4 Canonical SMILES
C1CCN(CC1)C2=NC(=N)N(C(=C2)N)O
2.2 Other Identifiers
2.2.1 UNII
5965120SH1
2.3 Synonyms
2.3.1 MeSH Synonyms

1. Loniten

2. Regaine

3. Rogaine

4. U 10858

2.3.2 Depositor-Supplied Synonyms

1. 38304-91-5

2. Rogaine

3. Loniten

4. Minoximen

5. Regaine

6. Theroxidil

7. Alopexil

8. Alostil

9. Tricoxidil

10. Lonolox

11. Normoxidil

12. Prexidil

13. Minodyl

14. Pierminox

15. Riup

16. Mintop

17. 6-(1-piperidinyl)-2,4-pyrimidinediamine 3-oxide

18. 2,4-pyrimidinediamine, 6-(1-piperidinyl)-, 3-oxide

19. U-10858

20. C9h15n5o

21. 3-hydroxy-2-imino-6-piperidin-1-ylpyrimidin-4-amine

22. Chebi:6942

23. 6-(piperidin-1-yl)pyrimidine-2,4-diamine 3-oxide

24. U-10,858

25. 6-amino-1,2-dihydro-1-hydroxy-2-imino-4-piperidinopyrimidine

26. Nsc-757106

27. Mls000028566

28. Minossidile [italian]

29. Minoxidilum [inn-latin]

30. Ncgc00015673-08

31. Minoxidilum

32. Smr000058963

33. 6-amino-2-imino-4-(piperidin-1-yl)-1,2-dihydropyrimidin-1-ol

34. Cas-38304-91-5

35. Apo-gain

36. U10858

37. Dsstox_cid_20685

38. Dsstox_rid_79541

39. 6-piperidin-1-ylpyrimidine-2,4-diamine 3-oxide

40. Dsstox_gsid_40685

41. 6-(1-piperidinyl)-2,4-pyrimidinediamine-3-oxide

42. 2,6-diamino-4-(piperidin-1-yl)pyrimidin-1-ium-1-olate

43. Neoxidil

44. Avacor And Mintop

45. Smr000326812

46. Loniten (tn)

47. Rogaine (tn)

48. Riup (tn)

49. 2,4-diamino-6-piperidinopyrimidine 3-oxide

50. Sr-01000075331

51. Sr-05000001479

52. Mfcd00063409

53. 3-oxido-6-piperidin-1-ylpyrimidin-3-ium-2,4-diamine

54. Kopdil

55. Regaine For Men

56. Minoxidil,(s)

57. Regaine For Women

58. Prestwick_521

59. 3-hydroxy-2-imino-6-(1-piperidyl)pyrimidin-4-amine

60. Tm-160

61. Men''''s Rogaine

62. Women''''s Rogaine

63. 6-amino-2-imino-4-(piperidin-1-yl)pyrimidin-1(2h)-ol

64. Rogaine Extra Strength

65. Pyrimidin-1(2h)-ol

66. Spectrum_000969

67. Tocris-0583

68. Minoxidil [inn]

69. Minoxidil [jan]

70. Minoxidil [mi]

71. Minoxidil Extra Strength

72. Minoxidil [hsdb]

73. Minoxidil [inci]

74. Minoxidil [usan]

75. Regid855572

76. Opera_id_1150

77. Prestwick0_000020

78. Prestwick1_000020

79. Prestwick2_000020

80. Prestwick3_000020

81. Spectrum2_001053

82. Spectrum3_000509

83. Spectrum4_000063

84. Spectrum5_001299

85. Lopac-m-4145

86. Minoxidil [vandf]

87. M1389

88. Chembl802

89. Minoxidil [mart.]

90. M 4145

91. Minoxidil [usp-rs]

92. Minoxidil [who-dd]

93. Minoxidil (u-10858)

94. Minoxidil (jan/usp/inn)

95. Cbiol_001798

96. Lopac0_000786

97. Schembl29698

98. Bspbio_000059

99. Bspbio_001385

100. Bspbio_002037

101. Kbiogr_000105

102. Kbiogr_000585

103. Kbioss_000105

104. Kbioss_001449

105. 16317-69-4

106. Mls000859953

107. Mls001077294

108. Divk1c_000160

109. Schembl232565

110. Spectrum1500415

111. Spbio_001006

112. Spbio_001980

113. Bpbio1_000065

114. Chembl609587

115. Gtpl4254

116. Minoxidil, >=99% (tlc)

117. Sgcut00112

118. Zinc1735

119. Minoxidil [orange Book]

120. Chembl1372483

121. Dtxsid9040685

122. Minoxidil [ep Monograph]

123. Bcbcmap01_000193

124. Bdbm81463

125. Chebi:92128

126. Hms500h22

127. Kbio1_000160

128. Kbio2_000105

129. Kbio2_001449

130. Kbio2_002673

131. Kbio2_004017

132. Kbio2_005241

133. Kbio2_006585

134. Kbio3_000209

135. Kbio3_000210

136. Kbio3_001537

137. Minoxidil [usp Monograph]

138. Ninds_000160

139. Bcpp000162

140. Bio1_000084

141. Bio1_000573

142. Bio1_001062

143. Bio2_000105

144. Bio2_000585

145. Hms1361f07

146. Hms1568c21

147. Hms1791f07

148. Hms1920p03

149. Hms1989f07

150. Hms2089l08

151. Hms2091f20

152. Hms2095c21

153. Hms2233e04

154. Hms2235n21

155. Hms3259p21

156. Hms3262m14

157. Hms3266o06

158. Hms3371e15

159. Hms3372m19

160. Hms3402f07

161. Hms3411g16

162. Hms3675g16

163. Hms3712c21

164. Pharmakon1600-01500415

165. Act04612

166. Bcp01409

167. Cas_4201

168. Hy-b0112

169. Nsc_4201

170. To_000070

171. Zinc6507066

172. Tox21_110193

173. Tox21_500786

174. Bdbm50237593

175. Ccg-40112

176. Nsc757106

177. S1383

178. Stl453211

179. Akos015920078

180. Akos016339636

181. Tox21_110193_1

182. 6-amino-2-imino-4-(piperidin-1-yl)

183. Ac-5271

184. Bcp9000929

185. Ccg-220020

186. Cs-1867

187. Db00350

188. Gs-3605

189. Ks-5164

190. Lp00786

191. Nc00686

192. Sdccgsbi-0050764.p005

193. Idi1_000160

194. Idi1_033855

195. Smp1_000192

196. Ncgc00015673-01

197. Ncgc00015673-02

198. Ncgc00015673-03

199. Ncgc00015673-04

200. Ncgc00015673-05

201. Ncgc00015673-06

202. Ncgc00015673-07

203. Ncgc00015673-09

204. Ncgc00015673-10

205. Ncgc00015673-11

206. Ncgc00015673-13

207. Ncgc00015673-20

208. Ncgc00018278-01

209. Ncgc00018278-02

210. Ncgc00018278-03

211. Ncgc00018278-04

212. Ncgc00024666-01

213. Ncgc00024666-02

214. Ncgc00024666-03

215. Ncgc00024666-04

216. Ncgc00024666-05

217. Ncgc00024666-06

218. Ncgc00024666-07

219. Ncgc00024666-08

220. Ncgc00179672-01

221. Ncgc00261471-01

222. Bd164673

223. Sbi-0050764.p004

224. 2,6-diamino-4-piperidinopyrimidine 1-oxide

225. 5965120sh1

226. Ab00513797

227. Eu-0100786

228. Ft-0620793

229. D00418

230. H10337

231. O10620

232. 6-(1-piperidinyl)-2,4-pyrimidinediamine3-oxide

233. Ab00052047-08

234. Ab00052047_09

235. Ab00052047_10

236. Ab00513797-02

237. 304m915

238. A824098

239. Q424165

240. Q-201408

241. Sr-01000075331-1

242. Sr-01000075331-3

243. Sr-01000075331-5

244. Sr-05000001479-1

245. Sr-05000001479-2

246. 2,4-diamino-6-piperidinopyrimidine 3-oxide.

247. 3-hydroxy-2-imino-6-(1-piperidinyl)-4-pyrimidinamine

248. Brd-k06902185-001-05-2

249. Brd-k06902185-001-10-2

250. Brd-k14888893-001-02-3

251. Minoxidil, British Pharmacopoeia (bp) Reference Standard

252. Z1541638524

253. Minoxidil, European Pharmacopoeia (ep) Reference Standard

254. 2-azanylidene-3-oxidanyl-6-piperidin-1-yl-pyrimidin-4-amine

255. 6-amino-1,2-dihydro-1-hydroxy-2-imino-4-piperidino-pyrimidine

256. Minoxidil, United States Pharmacopeia (usp) Reference Standard

257. Minoxidil For System Suitability, European Pharmacopoeia (ep) Reference Standard

2.4 Create Date
2005-03-25
3 Chemical and Physical Properties
Molecular Weight 209.25 g/mol
Molecular Formula C9H15N5O
XLogP31.2
Hydrogen Bond Donor Count3
Hydrogen Bond Acceptor Count3
Rotatable Bond Count1
Exact Mass209.12766012 g/mol
Monoisotopic Mass209.12766012 g/mol
Topological Polar Surface Area88.9 Ų
Heavy Atom Count15
Formal Charge0
Complexity329
Isotope Atom Count0
Defined Atom Stereocenter Count0
Undefined Atom Stereocenter Count0
Defined Bond Stereocenter Count0
Undefined Bond Stereocenter Count0
Covalently Bonded Unit Count1
4 Drug and Medication Information
4.1 Drug Information
1 of 16  
Drug NameMen's rogaine
PubMed HealthMinoxidil
Drug ClassesAlopecia Agent, Antihypertensive, Peripheral Vasodilator
Drug LabelMinoxidil tablets contain minoxidil, an antihypertensive peripheral vasodilator. Minoxidil occurs as a white to off-white, odorless, crystalline solid that is soluble in water to the extent of approximately 2 mg/mL, is readily soluble in propylene gl...
Active IngredientMinoxidil
Dosage FormAerosol, foam
RouteTopical
Strength5%
Market StatusOver the Counter
CompanyJohnson And Johnson

2 of 16  
Drug NameMinoxidil
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength2%
Market StatusOver the Counter
CompanyHi Tech Pharma; Perrigo

3 of 16  
Drug NameMinoxidil
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength2%
Market StatusOver the Counter
CompanyWockhardt; Hi Tech Pharma; Actavis Mid Atlantic; Perrigo

4 of 16  
Drug NameMinoxidil
Active IngredientMinoxidil
Dosage FormTablet; Aerosol, foam
RouteOral; Topical
Strength2.5mg; 5%; 10mg
Market StatusOver the Counter; Prescription
CompanyPar Pharm; Watson Labs; Mutual Pharm; Perrigo Israel

5 of 16  
Drug NameMinoxidil extra strength
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength5%
Market StatusOver the Counter
CompanyWockhardt; Avacor Prods; Actavis Mid Atlantic; Perrigo; Perrigo New York

6 of 16  
Drug NameRogaine
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength2%
Market StatusOver the Counter
CompanyJohnson And Johnson

7 of 16  
Drug NameRogaine extra strength
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength5%
Market StatusOver the Counter
CompanyJohnson And Johnson

8 of 16  
Drug NameTheroxidil
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength5%; 2%
Market StatusOver the Counter
CompanyEi

9 of 16  
Drug NameMinoxidil extra strength
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength5%
Market StatusOver the Counter
CompanyWockhardt; Avacor Prods; Actavis Mid Atlantic; Perrigo; Perrigo New York

10 of 16  
Drug NameRogaine
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength2%
Market StatusOver the Counter
CompanyJohnson And Johnson

11 of 16  
Drug NameRogaine extra strength
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength5%
Market StatusOver the Counter
CompanyJohnson And Johnson

12 of 16  
Drug NameTheroxidil
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength5%; 2%
Market StatusOver the Counter
CompanyEi

13 of 16  
Drug NameMen's rogaine
PubMed HealthMinoxidil
Drug ClassesAlopecia Agent, Antihypertensive, Peripheral Vasodilator
Drug LabelMinoxidil tablets contain minoxidil, an antihypertensive peripheral vasodilator. Minoxidil occurs as a white to off-white, odorless, crystalline solid that is soluble in water to the extent of approximately 2 mg/mL, is readily soluble in propylene gl...
Active IngredientMinoxidil
Dosage FormAerosol, foam
RouteTopical
Strength5%
Market StatusOver the Counter
CompanyJohnson And Johnson

14 of 16  
Drug NameMinoxidil
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength2%
Market StatusOver the Counter
CompanyHi Tech Pharma; Perrigo

15 of 16  
Drug NameMinoxidil
Active IngredientMinoxidil
Dosage FormSolution
RouteTopical
Strength2%
Market StatusOver the Counter
CompanyWockhardt; Hi Tech Pharma; Actavis Mid Atlantic; Perrigo

16 of 16  
Drug NameMinoxidil
Active IngredientMinoxidil
Dosage FormTablet; Aerosol, foam
RouteOral; Topical
Strength2.5mg; 5%; 10mg
Market StatusOver the Counter; Prescription
CompanyPar Pharm; Watson Labs; Mutual Pharm; Perrigo Israel

4.2 Therapeutic Uses

Antihypertensive Agents; Vasodilator Agents

National Library of Medicine's Medical Subject Headings online file (MeSH, 1999)


Minoxidil is indicated for treatment of hypertension. Because of its serious side effects, minoxidil is not considered to be a primary agent in the treatment of essential hypertension. It is recommended for use only in patients with symptomatic or organ-damaging hypertension not responsive to other treatment. /Included in US product labeling/

MICROMEDEX Thomson Health Care. USPDI - Drug Information for the Health Care Professional. 22nd ed. Volume 1. MICROMEDEX Thomson Health Care, Greenwood Village, CO. 2002. Content Reviewed and Approved by the U.S. Pharmacopeial Convention, Inc., p. 2077


Minoxidil is used topically to stimulate regrowth of hair in balding areas of individuals with androgenetic alopecia (male pattern alopecia, hereditary alopecia, common male baldness). The drug is effective in promoting hair regrowth on the vertex (crown) of the scalp but appears to have little or no effect on temporal recession; the efficacy of topical minoxidil therapy for frontal alopecia has not been evaluated objectively to date. There is evidence to suggest that individuals most likely to respond to topical minoxidil therapy are those younger than 40 years of age, those in whom treatment is initiated relatively early (less than 10 years' duration of hair loss), those with a small diameter of baldness (less than 10 cm), and those who have a large number of terminal or indeterminate (intermediate) hairs before initiation of treatment. At least 4 mo of continuous therapy with minoxidil topical solution usually is required for evidence of response; however, treatment for up to a year may be warranted before deciding that the alopecia is unresponsive. While the ultimate benefit of topical minoxidil therapy depends on the subjective perceptions of the treated individual, cosmetically acceptable hair regrowth as determined by study investigators has been reported in approximately one third of individuals after 6-12 mo of twice daily therapy in most clinical studies, and complete coverage of the balding areas of the scalp occurs rarely. Current evidence suggests that such therapy must be continued indefinitely for maintenance of hair growth.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3481-2


Topically applied minoxidil has been used as a 1, 3, or 5% solution, ointment, or cream to promote hair regrowth in males and females with alopecia areata, including those with the most severe forms, alopecia totalis (complete loss of scalp hair) or alopecia universalis (complete loss of body hair). Overnight petrolatum occlusion of the treated area, which has been reported to enhance efficacy, has been used in some studies. A cosmetically acceptable response to topical minoxidil therapy appears most likely to occur in patients with patchy alopecia areata; patients with total loss of scalp or body hair at baseline (eg; those with alopecia totalis or universalis) usually have the poorest and most delayed response. Efficacy of any therapy in patients with alopecia areata is difficult to evaluate because of the spontaneous hair regrowth and hair loss characteristic of the disease. As in androgenetic alopecia, some patients with alopecia areata receiving treatment with the vehicle alone in controlled studies have had regrowth of terminal hair, and hair loss has resumed in other patients during continued topical minoxidil therapy.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3482-3


For more Therapeutic Uses (Complete) data for MINOXIDIL (6 total), please visit the HSDB record page.


4.3 Drug Warning

It is particularly important that the risks versus benefits of topical minoxidil therapy be assessed carefully in individuals older than 50 yr of age; those with cardiac, renal, or hepatic disease or scalp abnormalities; and those receiving potentially interacting drugs concomitantly (eg; hypotensive agents such as guanethidine); such individuals should be closely monitored if a decision is made to initiate therapy. In addition, individuals with underlying cardiac disease, including coronary artery disease or congestive heart failure, should be informed that adverse systemic effects of topical minoxidil therapy may be particularly serious should they occur.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3484


Individuals receiving topical minoxidil therapy and their clinician should be aware of the manifestations of common and otherwise potentially serious adverse effects associated with systemic minoxidil therapy, particularly sodium and water retention, weight gain, local or generalized edema, pericardial effusion, pericarditis, tamponade, tachycardia, and increased frequency or development of angina. ... While such effects generally appear to be unlikely during topical minoxidil therapy, certain individuals may be at increased risk of their development because of underlying disease, sensitivity to the drug, or achievement of higher than usual systemic concentrations (eg; secondary to misuse or enhanced percutaneous penetration of topical drug). Individuals receiving topical minoxidil therapy should be advised to watch for and report the occurrence of increased heart rate, weight gain, difficulty in breathing (especially when lying down), worsening or development of angina pectoris, edema (swelling) of the face, hands, ankles, or abdomen, or other systemic effects and should be monitored 1 mo after initiating therapy and at least every 6 mo thereafter for the possible development of such effects. If systemic effects occur, topical minoxidil therapy should be discontinued.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3484


As with other topically applied drugs, inflammation or disease processes associated with decreased integrity of the epidermal barrier (eg; excoriations of the scalp, severe sunburn, scalp psoriasis) may increase percutaneous absorption of minoxidil and potentially increase the likelihood of systemic adverse effects.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3484


In evaluating females in whom androgenetic alopecia is suspected, the possibility of an underlying endocrine abnormality such as Cushing's disease, polycystic ovary (Stein-Leventhal) syndrome, hypothyroidism, or an androgen secreting tumor should be considered.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3484


For more Drug Warnings (Complete) data for MINOXIDIL (14 total), please visit the HSDB record page.


4.4 Drug Indication

For the treatment of severe hypertension and in the topical treatment (regrowth) of androgenic alopecia in males and females and stabilisation of hair loss in patients with androgenic alopecia.


FDA Label


5 Pharmacology and Biochemistry
5.1 Pharmacology

Minoxidil is an orally effective direct acting peripheral vasodilator that reduces elevated systolic and diastolic blood pressure by decreasing peripheral vascular resistance. Minoxidil is also used topically to treat androgenetic alopecia. Microcirculatory blood flow in animals is enhanced or maintained in all systemic vascular beds. In man, forearm and renal vascular resistance decline; forearm blood flow increases while renal blood flow and glomerular filtration rate are preserved. The predominant site of minoxidil action is arterial. Venodilation does not occur with minoxidil; thus, postural hypotension is unusual with its administration. The antihypertensive activity of minoxidil is due to its sulphate metabolite, minoxidil sulfate.


5.2 MeSH Pharmacological Classification

Antihypertensive Agents

Drugs used in the treatment of acute or chronic vascular HYPERTENSION regardless of pharmacological mechanism. Among the antihypertensive agents are DIURETICS; (especially DIURETICS, THIAZIDE); ADRENERGIC BETA-ANTAGONISTS; ADRENERGIC ALPHA-ANTAGONISTS; ANGIOTENSIN-CONVERTING ENZYME INHIBITORS; CALCIUM CHANNEL BLOCKERS; GANGLIONIC BLOCKERS; and VASODILATOR AGENTS. (See all compounds classified as Antihypertensive Agents.)


Vasodilator Agents

Drugs used to cause dilation of the blood vessels. (See all compounds classified as Vasodilator Agents.)


5.3 FDA Pharmacological Classification
5.3.1 Active Moiety
MINOXIDIL
5.3.2 FDA UNII
5965120SH1
5.3.3 Pharmacological Classes
Arteriolar Vasodilator [EPC]; Arteriolar Vasodilation [PE]
5.4 ATC Code

D11AX01

S76 | LUXPHARMA | Pharmaceuticals Marketed in Luxembourg | Pharmaceuticals marketed in Luxembourg, as published by d'Gesondheetskeess (CNS, la caisse nationale de sante, www.cns.lu), mapped by name to structures using CompTox by R. Singh et al. (in prep.). List downloaded from https://cns.public.lu/en/legislations/textes-coordonnes/liste-med-comm.html. Dataset DOI:10.5281/zenodo.4587355


C - Cardiovascular system

C02 - Antihypertensives

C02D - Arteriolar smooth muscle, agents acting on

C02DC - Pyrimidine derivatives

C02DC01 - Minoxidil


D - Dermatologicals

D11 - Other dermatological preparations

D11A - Other dermatological preparations

D11AX - Other dermatologicals

D11AX01 - Minoxidil


5.5 Absorption, Distribution and Excretion

Absorption

Minoxidil is at least 90% absorbed from the GI tract in experimental animals and man.


Minoxidil is almost completely absorbed (95%) from the GI tract. Peak plasma levels are reached in 1 hr. Protein binding does not occur. Minoxidil is widely distributed in the tissues, with an apparent volume of distribution of about 2.8-3.3 l/kg. Placental passage and distribution into breast milk have not been established. The elimination half-life of minoxidil is2.77-4.2 hr. About 90% of an oral dose of minoxidil is metabolized in the liver. The drug and its metabolites are largely excreted in the urine. Renal clearance is 73.9 ml/min.

Ellenhorn, M.J. and D.G. Barceloux. Medical Toxicology - Diagnosis and Treatment of Human Poisoning. New York, NY: Elsevier Science Publishing Co., Inc. 1988., p. 314


Percutaneous absorption of minoxidil appears to be minimal following topical application of minoxidil solution to intact scalp. However, systemic absorption of topically applied minoxidil is variable and depends on several factors, including the vehicle used in the formulation, the area of application, condition of the skin (eg; being increased with local abrasion or inflammation), and interindividual variation in the extent of percutaneous absorption. Percutaneous absorption of the drug does not appear to be altered by use of a hot-air hair dryer. Although limited in vitro evidence suggests comparable release of minoxidil from solutions with different proportions of propylene glycol, alcohol, and water, release of the drug from a cream base differs substantially from that from solution formulations, and water-in-oil creams appear to differ markedly from oil-in-water creams or ointments in terms of the rate and concentration dependency of drug permeation through human skin. Absorption of minoxidil from extemporaneously prepared solutions, ointments, creams, or other such topical formulations may not be comparable to that from the commercially available topical minoxidil solution.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3486


Percutaneous absorption of minoxidil following topical application of 2% hydroalcoholic, propylene glycol-containing solutions of the drug generally has been reported to average 0.3-4.5% of the applied dose. In a preliminary study in healthy balding men, the systemic bioavailability of minoxidil 2 or 3% topical solution (20 or 30 mg doses, respectively) at steady state relative to that of a 2.5 mg oral tablet averaged 1.4 or 1.2%, respectively. Based on urinary excretion of radiolabeled drug administered to healthy men in another study, percutaneous absorption of minoxidil after application of 1 or 5% minoxidil solutions to the scalp generally averaged 1.6-3.9% of the applied dose, based on urinary recovery of radiolabeled drug. In studies in animals, 5-36% of topically applied doses was absorbed systemically. Serum concentrations achieved after topical application of minoxidil solutions are variable, and clinical studies of topical minoxidil therapy have found no correlation between serum minoxidil concentrations and hair growth. In controlled studies in individuals with androgenetic alopecia or alopecia areata, serum concentrations of minoxidil after topical application of 1, 2, 3, or 5% solution formulations (with or without nightly petrolatum occlusion) generally averaged 2 ng/ml or less. However, about 1% of individuals receiving a 2% topical solution achieved peak serum concentrations of 5 ng/ml or greater, and a few patients achieved concentrations approaching 30 ng/ml. In part, increased percutaneous absorption of the drug in some individuals may have resulted from alterations in the stratum corneum (eg; secondary to irritation and inflammation from shaving of the scalp). In addition, some individuals may have a propensity for enhanced percutaneous absorption of the drug. Data from healthy balding men indicate that peak serum concentrations of unchanged minoxidil after oral doses of 5 mg daily generally are 20-30 times higher than mean serum concentrations achieved after twice daily topical application of approximately 20 mg (1 ml) of minoxidil as a 2% solution.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3486


The distribution of topically applied minoxidil has not been fully determined. Limited evidence suggests that intact stratum corneum serves as a barrier that inhibits substantial diffusion of topically applied minoxidil into systemic circulation, but additional study is needed. Skin biopsy specimens obtained after topical application of a radiolabeled minoxidil 1 or 5% solution to the scalp of healthy balding men indicate an average retention in the skin of 2.6% or less of the applied dose after 24 hr, with twice as much radioactivity in the dermis as in the epidermis. The remainder of the dose remained on the skin or presumably was lost to the environment.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3486


For more Absorption, Distribution and Excretion (Complete) data for MINOXIDIL (8 total), please visit the HSDB record page.


5.6 Metabolism/Metabolites

Approximately 90% of the administered drug is metabolized, predominantly by conjugation with glucuronic acid at the N-oxide position in the pyrimidine ring, but also by conversion to more polar products. Known metabolites exert much less pharmacologic effect than minoxidil itself.


Preliminary evidence suggests that the activity of minoxidil sulfotransferase (the enzyme that converts the drug to its sulfate) is higher in the hair follicle than in epidermis or dermis. Minoxidil sulfate, which may be formed preferentially in the hair follicle following topical application of the drug, exhibits more potent vasodilatory activity than the parent drug.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3485


About 90% of an oral dose of minoxidil is metabolized, primarily by conjugation with glucuronic acid and also by conversion to more polar metabolites. Minoxidil's metabolites are considerably less active than the parent drug.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 1852


The biotransformation of minoxidil (2,4-diamino-6-piperidinopyrimidine 3-oxide) was studied in the rat, dog, and monkey and compared to reported results in the human. Chromatographic profiles of urinary metabolites show that each species excreted substantially the same metabolites but in quite different relative amounts. The monkey and the human exhibited similar metabolite profiles, whereas the dog and rat were quantitatively different from each other and from the monkey and human. The major excretory product for the monkey and human was a glucuronide conjugate of minoxidil. Substantially smaller amounts of unchanged minoxidil, 2,4-diamino-6-(4'-hydroxypiperidino)pyrimidine 3-oxide, and more polar metabolites also were excreted by these two species. The major excretory product in the rat was unchanged minoxidil. Almost as much (combined) of the two acidic metabolites, 2,4-diamino-6-(4'-carboxy-n-butylamino)pyrimidine and its 3-oxide, also were produced. Smaller amounts of the glucuronide of minoxidil, 2,4-diamino-6-(4'-hydroxypiperidino)pyrimidine 3-oxide, its 3'-hydroxy isomer, and 2,4-diamino-6-piperidinopyrimidine also were excreted by the rat. The major metabolite of minoxidil excreted by the dog was the 4'-hydroxy metabolite. Smaller amounts of unchanged minoxidil and polar metabolites and much smaller amounts of the glucuronide of minoxidil, the 3'-hydroxy metabolite, and 2,4-diamino-6-piperidinopyrimidine also were excreted by the dog. Evidence was obtained for a glucuronide conjugate of the 4'-hydroxy metabolite in this species. The major circulatory material in dog plasma was the 4'-hydroxy metabolite, whereas it was the glucuronide of minoxidil in monkey plasma.

PMID:807713 Thomas RC, Harpootlian H; J Pharm Sci 64 (8): 1366-71 (1975)


Minoxidil has known human metabolites that include 2-Pyrimidinamine, 1,6-dihydro-6-imino-4-(1-piperidinyl)-1-(sulfooxy)-.

S73 | METXBIODB | Metabolite Reaction Database from BioTransformer | DOI:10.5281/zenodo.4056560


5.7 Biological Half-Life

4.2 hours


In one study in patients with various degrees of renal function (eg; normal to uremic), the mean plasma half-life of minoxidil and its metabolites was 4.2 hr.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 1852


5.8 Mechanism of Action

Minoxidil is thought to promote the survival of human dermal papillary cells (DPCs) or hair cells by activating both extracellular signal-regulated kinase (ERK) and Akt and by preventing cell death by increasing the ratio of BCl-2/Bax. Minoxidil may stimulate the growth of human hairs by prolonging anagen through these proliferative and anti-apoptotic effects on DPCs. Minoxidil, when used as a vasodilator, acts by opening adenosine triphosphate-sensitive potassium channels in vascular smooth muscle cells. This vasodilation may also improve the viability of hair cells or hair follicles.


The mechanism(s) by which topically applied minoxidil and/or a metabolite of the drug stimulate vertex hair regrowth in androgenetic (male-pattern) alopecia or other forms of alopecia has not been fully elucidated. However, because minoxidil has stimulated hair regrowth in several forms of alopecia, it appears that the drug acts at the level of the hair follicle, possibly involving direct stimulation of hair follicle epithelial growth. ... While increased scalp blood flow resulting from local vasodilation often has been proposed as a principal mechanism of minoxidil's effect on hair growth, this mechanism has not been substantiated consistently and not all vasodilators produce hypertrichosis.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3485


Studies in animal cell cultures indicate that minoxidil directly induces proliferation of hair epithelial cells near the base of the hair follicle and increases incorporation of cysteine and glycine into the follicle; cysteine residues crosslink to form cystine, which provides strength to the hair shaft. The drug also appears to induce hypertrophy of existing small follicles, prolong the anagen phase of the hair follicle, and accelerate the cyclic turnover of vellus hair follicles, enabling these follicles to produce thick, terminal hair; these effects result in a decrease in vellus hair follicles, an increase in terminal hair follicles, and an increase in the diameter of the hair shaft. Biopsy specimens obtained after topical treatment with minoxidil demonstrate enlargement of preexisting hair follicles but no evidence of new hair follicle formation.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3485


In vitro studies demonstrate different effects of minoxidil on epithelial cells and lymphocytes, which may lead to synergistic effects on hair growth in patients with alopecia areata. In cultures of murine epithelial cells, minoxidil increased cell proliferation, prolonged cell passage time (delayed senescence), and altered cell morphology; the latter 2 effects also have been observed in cultures of human keratinocytes. Human lymphocytes exposed to minoxidil in cell culture demonstrated a modest suppression of mitogen-induced blast formation.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 3486


Minoxidil reduces peripheral vascular resistance and blood pressure as a result of a direct vasodilating effect on vascular smooth muscle; like diazoxide and hydralazine, minoxidil's effect on arterioles is greater than on veins. Minoxidil delays the hydrolysis of cyclic 3',5'-adenosine monophosphate and cyclic guanosine monophosphate by inhibiting the enzyme phosphodiesterase, and relaxation of arterial smooth muscle by the drug may be, at least partly, mediated by cyclic 3',5'-adenosinemonophospate. Animal studies indicate that minoxidil does not have CNS or adrenergic neuronal blocking effects.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 1851