Class: Skin and Mucous Membrane Agents, Miscellaneous
ATC Class: C02DC01
VA Class: DE900
Chemical Name: 3-oxide 6-(1-piperidinyl)-2,4-pyrimidinediamine
Molecular Formula: C9H15N5O
CAS Number: 38304-91-5
Brands: Hair Regrowth, Rogaine, Theroxidil
Introduction
Hair stimulant; a piperidinopyrimidine-derivative vasodilator.5 19 20 37 43 44 73 4 9 14 15 20 40 43 56
Uses for Minoxidil
Androgenetic Alopecia
Stimulates regrowth of hair in men and women with androgenetic alopecia (male-pattern alopecia, hereditary alopecia, common male baldness).1 5 6 7 8 9 15 16 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 39 40 59 83 85
Recommended for use in men who have general thinning of hair at the vertex of the scalp 115 116 121 122 123 126 and in women who have general thinning of hair in frontoparietal areas.115 117 May be ineffective in men or women with more extensive hair loss.116 117 121 122 123 126
Not recommended for patients without a family history of hair loss or for those with hair loss associated with childbirth, or for those who have hair loss that occurs suddenly or for unknown reasons.116 117 121 122 123 126
Generally most effective in men <40 years of age,5 115 116 100 101 with <10 years duration of hair loss,6 23 39 100 101 115 116 <10 cm diameter of baldness, 5 6 23 39 100 101 115 116 and with large number of terminal or intermediate hairs before initiation of therapy.5 23 39 100 101
Alopecia Areata
Has been used to promote hair regrowth in males and females with alopecia areata†, including alopecia totalis or universalis.9 44 45 46 47 48 49 50 51 52 53
Hair Transplantation
Has been used as an adjunct to hair transplantation†; may promote better evolution of hair grafts by reducing postoperative shedding of hair and hastening the onset of postsheddng hair regrowth.64 65
Minoxidil Dosage and Administration
Administration
Topical Administration
Apply topically to the scalp as a 2 or 5% solution or as a 5% foam.1 116 117 121 122 123 126 a b c d
For dermatologic use only;1 116 117 121 122 123 126 avoid contact with eyes, mucous membranes, or sensitive or abraded skin areas.1 40 85 101 (See Dermatologic Effects under Cautions.) If contact with any of these areas occurs, flush area with large amounts of cool water.1 85 116 117 121 122 123
Apply to the scalp only; do not apply to other areas of the body because of risk of systemic adverse effects.116 117 121 122 123 126 (See Systemic Effects under Cautions.)
In men, apply 2 or 5% solution or 5% foam to total affected (balding and anticipated balding) areas of the scalp twice daily, usually in the morning and evening.1 5 6 7 8 9 15 16 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 39 40 59 83 101 116 117 121 122 123 126 c
In women, apply 2% solution to total affected areas of the scalp twice daily, usually in the morning and evening;117 d 5% solution and 5% foam should not be used in women.126 b c
Apply solution and foam to dry scalp.1 85 116 117 121 122 123 126 a b c d
To apply solution, use applicator provided by the manufacturer and apply evenly over total affected areas of the scalp.85 a b d
To apply foam, part hair into ≥1 rows to expose scalp.c Rinse hands with cold water and dry thoroughly to minimize foam melting on warm skin.c Hold container upside down and press nozzle to dispense ½ capful of foam onto fingers; apply foam to affected areas and gently massage into scalp.c
Wash hands thoroughly after application using fingertips.1 116 117 121 122 123 126 a b c d
Dosage
Adults
Androgenetic Alopecia
Treatment in Men
Topical
Apply 1 mL of 2 or 5% solution to affected areas of the scalp twice daily.1 5 6 7 8 9 15 16 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 39 40 59 83 101 116 117 121 122 123 126 a b
Apply ½ capful of 5% foam to affected areas of the scalp twice daily.c
≥4 months of use may be necessary before regrowth observed.1 5 6 7 67 101 116 117 121 122 123 126 a b c d Therapy must be continued indefinitely for maintenance of hair growth.1 6 7 9 24 40 67 83 100 101 109 115 116 121 122 123 126
Treatment in Women
Topical
Apply 1 mL of 2% solution to affected areas of the scalp twice daily.117 d
≥4 months of use may be necessary before regrowth observed.1 5 6 7 67 101 116 117 121 122 123 126 a b c d Therapy must be continued indefinitely for maintenance of hair growth.1 6 7 9 24 40 67 83 100 101 109 115 116 121 122 123 126
Alopecia Areata†
Topical
Apply 1 mL of 5% solution to affected areas of the scalp twice daily.45 46 49 52 53 100 101
Prescribing Limits
Adults
Androgenetic Alopecia
Treatment in Men
Topical
Maximum 2 mL of 2 or 5% solution daily.1 116 117 121 122 123 126 a b d
Maximum ½ capful of 5% foam per application.c
Treatment in Women
Topical
Maximum 2 mL of 2% solution daily.1 116 117 121 122 123 126 a d
Special Populations
No special population dosage recommendations at this time.a b c d
Cautions for Minoxidil
Contraindications
Known hypersensitivity to minoxidil or any ingredient in the formulation.1
Warnings/Precautions
General Precautions
Dermatologic Effects
Possible adverse local dermatologic effects (e.g., pruritus, dryness, scaling/flaking, local irritation or burning);1 5 8 9 15 16 22 23 26 27 29 30 32 40 46 56 83 85 96 may occur more frequently with the 5 than the 2% topical solution126 and may result from alcohol contained in formulation1 85 and the wearing of a wig or hairpiece.53 Local irritation usually is mild1 5 9 15 16 26 29 38 39 46 51 53 56 83 85 96 and rarely requires discontinuance of therapy.46 51 56
If irritation occurs, flush area with large amounts of cool water; contact clinician if irritation persists.1 85 116 117 121 122 123
Increased hair growth outside area of drug application (e.g., face, beard, eyebrows, ear, arm) reported; possibly due to inadvertent transfer of drug solution.1 5 22 32 46 50 51 52 83
Systemic Effects
Potential systemic adverse effects (e.g., weight gain, edema, tachycardia, hypotension),1 9 22 32 40 86 93 100 110 111 especially in individuals with propensity for greater percutaneous absorption or with increased sensitivity to the drug.1 9 93 101 Excessive doses, local abrasion or inflammation, or severe sunburn also may increase risk of systemic effects.1 101 116 117 121 122 123 a b d
Use not recommended on inflamed, erythematous, infected, irritated, or painful scalp.116 117 121 122 123 a b c d
Exposure to UV Light
Severe UV light-induced skin injury (e.g., severe sunburn) may enhance percutaneous absorption and increase risk of systemic effects.1 101 (See Systemic Effects under Cautions.)
Specific Populations
Pregnancy
Category C.e
Lactation
Distributed into milk after oral administration;72 115 however, not known whether topical minoxidil is distributed into milk.d AAP classifies minoxidil as compatible with breast-feeding.e
Pediatric Use
Safety and efficacy not established in children <18 years of age.1
Women
Prior to initiating therapy for androgenetic alopecia, consider possibility of an underlying endocrine abnormality (e.g., polycystic ovary [Stein-Leventhal] syndrome, Cushing’s syndrome, androgen-secreting tumors, hypothyroidism).9 84 100 101
Severe, diffuse hypertrichosis involving the face and limbs reported in women after 2–3 months of therapy with 5% solution for treatment of androgenetic alopecia; resolved within 4–5 months following discontinuance of therapy.132
Common Adverse Effects
Pruritus, 1 5 8 9 15 16 22 23 26 27 29 30 32 40 46 56 83 85 96 dryness, 5 22 40 83 scaling/flaking, 1 5 9 26 46 83 local irritation or burning.1 5 9 15 16 26 29 38 39 46 51 53 56 83 85 96
Interactions for Minoxidil
Topical Preparations
Possible pharmacokinetic interaction (increased percutaneous absorption of minoxidil).101 129 130 Safety and efficacy of combined therapy with other topical drugs not established.131 Concomitant use with other topical drugs on the scalp is not recommended.a b c d
Specific Drugs
Drug | Interaction | Comments |
|---|---|---|
Hypotensive agents (guanethidine) | Possible increased risk of orthostatic hypotension if systemic absorption of minoxidil occurs1 | Use concomitantly with caution1 |
Tretinoin, topical | Potential increased percutaneous absorption of minoxidil101 129 130 | Safety and efficacy of combined use requires further evaluation131 |
Minoxidil Pharmacokinetics
Absorption
Bioavailability
Minimally absorbed following topical application to intact scalp;1 15 16 43 61 1.4% of a 2% topical solution may be absorbed.70
Onset
Onset of hair regrowth is variable; however, 2 or ≥4 months usually required before evidence of regrowth is observed following topical administration with 2 or 5% topical solutions, respectively.1 23 25 27 30 34 36 59 101 116 117 121 122 123 126
Distribution
Extent
Not fully determined following topical administration;100 101 however, intact stratum corneum may serve as a barrier that inhibits substantial diffusion of topically applied minoxidil into systemic circulation.68 71 101
Not known whether topical minoxidil crosses the placenta or is distributed into milk.1 72 e
Elimination
Metabolism
Not fully determined following topical administration;1 however, appears to be converted in the hair follicle to an active metabolite, minoxidil sulfate, by minoxidil sulfotransferase.17
Elimination Route
Excreted principally in urine.61
Stability
Storage
Topical
Solution
20–25°C.126 132 Keep away from heat and flame.a b d
Foam
20–25°C.c Keep away from heat and flame; do not puncture or incinerate container.c
ActionsActions
Exact mechanism of action not fully elucidated; however, appears to act at the level of the hair follicle,4 5 6 7 9 10 14 15 16 17 18 19 20 31 62 81 possibly directly stimulating hair follicle epithelial growth.4 6 9 10 14 15 17 18 19 20 81 100
May induce follicle hypertrophy and a return to more normal hair follicle diameter and depth in existing small follicles (i.e., regrowth) rather than stimulation of new follicle formation.4 5 6 7 9 17 19 20 59
Appears to prolong the anagen phase of the hair follicle, and accelerate the cyclic turnover of vellus hair follicles, enabling these follicles to produce thick, terminal hair4 6 9 19 20 106
May directly induce proliferation of hair epithelial cells near the base of the hair follicle and increase incorporation of cysteine and glycine into the follicle;14 cysteine residues cross-link to form cystine, which provides strength to the hair shaft.59
Advice to Patients
Product is flammable; importance of keeping product and area of application away from open flame and heat.a b c d
Importance of using only as directed, only for the indicated types of hair loss, and for at least 2–4 months in order to see results; continuous use required to maintain hair regrowth.a b c d (See Topical Administration under Dosage and Administration.)
Importance of applying only to healthy, normal scalp and not using topical minoxidil if scalp is inflamed, erythematous, infected, irritated, or painful.116 117 121 122 123 Importance of avoiding contact with the eyes.a b c d
Importance of washing hands after application.a b c d
Importance of women using only 2% solution; 5% solution and 5% foam should not be used in women.a b c d
Importance of reporting any local or systemic adverse reactions, especially chest pain, tachycardia, dizziness, unexplained weight gain, or peripheral edema, to a clinician.a b c d
Importance of informing clinicians of existing or contemplated therapy, including prescription and OTC drugs and dietary or herbal supplements, as well as concomitant illnesses.a b c d
Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.a b c d
Importance of informing patients of other important precautionary information.a b c d (See Cautions.)
Preparations
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
Topical | Solution | 2%* | Hair Regrowth (with alcohol 60% and propylene glycol) | Eckerd, Rite Aid |
Rogaine Hair Regrowth Treatment for Men (with alcohol 60% and propylene glycol) | Pfizer | |||
Rogaine Hair Regrowth Treatment for Women (with alcohol 60% and propylene glycol) | Pfizer | |||
5%* | Rogaine for Men Extra Strength (with alcohol 30% and propylene glycol) | Pfizer | ||
Theroxidil (with alcohol 30% and propylene glycol) | Harmony | |||
Foam | 5%* | Rogaine Hair Regrowth Treatment for Men (with alcohol SD 40-B, butane, butylated hydroxytoluene, isobutane, and propane) | Pfizer |
Disclaimer
This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.
The American Society of Health-System Pharmacists, Inc. and Drugs.com represent that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. and Drugs.com make no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. and Drugs.com do not endorse or recommend the use of any drug. The information is not a substitute for medical care.
AHFS Drug Information. © Copyright, 1959-2011, Selected Revisions November 2007. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.
† Use is not currently included in the labeling approved by the US Food and Drug Administration.
References
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