Minoxidil
Encyclopedia
Minoxidil is an antihypertensive vasodilator medication
which also slows or stops hair loss
and promotes hair regrowth. Now off-patent, it is available over-the-counter
for the treatment of androgenic alopecia. Minoxidil must be used indefinitely for continued support of existing hair follicles and the maintenance of any experienced hair regrowth. It is marketed under many trade names, including Rogaine/Regaine, Vanarex, , Mintop and Loniten (oral), and Avacor Physician's Formulation (Avacor
also produce a number of hair loss treatments that do not include minoxidil).
produced a topical
solution that contained 2% minoxidil to be used to treat baldness and hair loss, under the brand name Rogaine in the United States and Canada, and Regaine in Europe and the Asia-Pacific. Treatments usually include a 5% concentration solution that is designed for men, whereas the 2% concentration solutions are designed for women. The patent on minoxidil expired February 11, 1996. While the drug is available in the United Kingdom
, it cannot be prescribed on the NHS
, so patients must either buy it over-the-counter or have a private prescription for it.
In 2007, a new foam-based formulation of 5% minoxidil, which is claimed to be as effective as the liquid-based formulation, was introduced by Upjohn and marketed under the brand name Rogaine/Regaine Foam.
chemical moiety
and may act as a nitric oxide agonist. Similarly, minoxidil is a potassium channel opener
, causing hyperpolarization
of cell membranes. Minoxidil is less effective when there is a large area of hair loss. In addition, its effectiveness has largely been demonstrated in younger men who have experienced hair loss for less than 5 years. Minoxidil use is indicated for central (vertex
) hair loss only. Minoxidil is also a vasodilator. It is speculated that by widening blood vessels and opening potassium channels, it allows more oxygen, blood, and nutrients to the follicle. This may cause follicles in the telogen phase to shed, which are then replaced by thicker hairs in a new anagen phase.
Alcohol present in topical preparations may dry the scalp, resulting in dandruff
.
Side effects of oral minoxidil may include swelling of the face and extremities, rapid and irregular heartbeat, lightheadedness, cardiac lesions, and focal necrosis
of the papillary muscle
and subendocardial areas of the left ventricle. There have been cases of allergic reactions to minoxidil or the non-active ingredient propylene glycol
, which is found in some topical minoxidil formulations. Pseudoacromegaly is an extremely rare side effect reported with large doses of oral minoxidil.
Paradoxically, hair loss is a common side effect of minoxidil treatment. Manufacturers note that minoxidil-induced hair loss is a common side effect and describe the process as "shedding". Although this phenomenon demonstrates that minoxidil is indeed affecting hair follicles, manufacturers offer no guarantee that the new hair loss will be replaced with hair growth. The speculated reason for this shedding is the encouragement of hairs already in the telogen phase to shed early, before often beginning a fresh, healthier anagen phase.
Minoxidil is highly toxic to cats and may cause death with inadvertent skin contact.
or the enzyme responsible for its accumulation around the hair follicle, 5-alpha reductase
, which is the primary mediator of male pattern baldness in genetically susceptible individuals. Therefore, when treatment is stopped, the DHT
has its expected effect of shrinking and ultimately destroying the genetically predisposed hair follicles.
Minoxidil solutions are sold under many brand names. Many high priced as well as generic brands of minoxidil regrowth solutions exist and do not differ in their active ingredient or concentration. Minoxidil products involve contact with hair strands which may cause problems with hair styling as minoxidil must be in an alcohol-based solution. If the solution does not pose any issues, hair styling products may be applied after it has dried.
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
which also slows or stops hair loss
Baldness
Baldness implies partial or complete lack of hair and can be understood as part of the wider topic of "hair thinning". The degree and pattern of baldness can vary greatly, but its most common cause is male and female pattern baldness, also known as androgenic alopecia, alopecia androgenetica or...
and promotes hair regrowth. Now off-patent, it is available over-the-counter
Over-the-counter drug
Over-the-counter drugs are medicines that may be sold directly to a consumer without a prescription from a healthcare professional, as compared to prescription drugs, which may be sold only to consumers possessing a valid prescription...
for the treatment of androgenic alopecia. Minoxidil must be used indefinitely for continued support of existing hair follicles and the maintenance of any experienced hair regrowth. It is marketed under many trade names, including Rogaine/Regaine, Vanarex, , Mintop and Loniten (oral), and Avacor Physician's Formulation (Avacor
Avacor
Avacor® is the brand name of a line of products designed for both men and women to treat hair loss. The Avacor Physician's Formulation® is the only Avacor® product containing the U.S. Food and Drug Administration approved drug minoxidil, proven to regrow hair...
also produce a number of hair loss treatments that do not include minoxidil).
History
Minoxidil was first used exclusively as an oral drug (with the trade name 'Loniten') to treat high blood pressure. However, it was discovered to have an interesting side effect: Minoxidil may cause increased growth or darkening of fine body hairs, or in some cases, significant hair growth. When the medication is discontinued, the hair loss will return to normal rate within 30 to 60 days. Upjohn CorporationUpjohn
The Upjohn Company was a pharmaceutical manufacturing firm founded in 1886 in Kalamazoo, Michigan by Dr. William E. Upjohn, an 1875 graduate of the University of Michigan medical school. The company was originally formed to make friable pills, which were specifically designed to be easily digested...
produced a topical
Topical
In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, anus, throat, eyes and ears.Many topical medications are epicutaneous, meaning that they are applied directly to the skin...
solution that contained 2% minoxidil to be used to treat baldness and hair loss, under the brand name Rogaine in the United States and Canada, and Regaine in Europe and the Asia-Pacific. Treatments usually include a 5% concentration solution that is designed for men, whereas the 2% concentration solutions are designed for women. The patent on minoxidil expired February 11, 1996. While the drug is available in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, it cannot be prescribed on the NHS
National Health Service
The National Health Service is the shared name of three of the four publicly funded healthcare systems in the United Kingdom. They provide a comprehensive range of health services, the vast majority of which are free at the point of use to residents of the United Kingdom...
, so patients must either buy it over-the-counter or have a private prescription for it.
In 2007, a new foam-based formulation of 5% minoxidil, which is claimed to be as effective as the liquid-based formulation, was introduced by Upjohn and marketed under the brand name Rogaine/Regaine Foam.
Mechanism
The mechanism by which minoxidil promotes hair growth is not fully understood. Minoxidil contains the nitric oxideNitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...
chemical moiety
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
and may act as a nitric oxide agonist. Similarly, minoxidil is a potassium channel opener
Potassium channel opener
A potassium channel opener is a type of drug which facilitates ion transmission through potassium channels.Some examples include:* Diazoxide vasodilator used for hypertension, smooth muscle relaxing activity...
, causing hyperpolarization
Hyperpolarization (biology)
Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization.Hyperpolarization is often caused by efflux of K+ through K+ channels, or influx of Cl– through Cl– channels. On the other hand, influx of cations, e.g...
of cell membranes. Minoxidil is less effective when there is a large area of hair loss. In addition, its effectiveness has largely been demonstrated in younger men who have experienced hair loss for less than 5 years. Minoxidil use is indicated for central (vertex
Vertex (anatomy)
In arthropod and vertebrate anatomy, the vertex refers to the upper surface of the head.In humans, the vertex is formed by four bones of the skull: the frontal bone, the two parietal bones, and the occipital bone...
) hair loss only. Minoxidil is also a vasodilator. It is speculated that by widening blood vessels and opening potassium channels, it allows more oxygen, blood, and nutrients to the follicle. This may cause follicles in the telogen phase to shed, which are then replaced by thicker hairs in a new anagen phase.
Side effects
Common side effects of minoxidil include burning or irritation of the eye, itching, redness or irritation at the treated area, as well as unwanted hair growth elsewhere on the body. Users should stop treatment and seek medical attention right away if they experience any of the following serious side effects: Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); chest pain; dizziness; fainting; fast heartbeat; sudden, unexplained weight gain; swollen hands or feet.Alcohol present in topical preparations may dry the scalp, resulting in dandruff
Dandruff
Dandruff is the shedding of dead skin cells from the scalp . Dandruff is sometimes caused by frequent exposure to extreme heat and cold. As it is normal for skin cells to die and flake off, a small amount of flaking is normal and common; about 487,000 cells/cm2 get released normally after...
.
Side effects of oral minoxidil may include swelling of the face and extremities, rapid and irregular heartbeat, lightheadedness, cardiac lesions, and focal necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
of the papillary muscle
Papillary muscle
In anatomy, the papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves via the chordae tendinae and contract to prevent inversion or prolapse of these valves.- Action :There are five total papillary muscles in the heart, three...
and subendocardial areas of the left ventricle. There have been cases of allergic reactions to minoxidil or the non-active ingredient propylene glycol
Propylene glycol
Propylene glycol, also called 1,2-propanediol or propane-1,2-diol, is an organic compound with formula C3H8O2 or HO-CH2-CHOH-CH3...
, which is found in some topical minoxidil formulations. Pseudoacromegaly is an extremely rare side effect reported with large doses of oral minoxidil.
Paradoxically, hair loss is a common side effect of minoxidil treatment. Manufacturers note that minoxidil-induced hair loss is a common side effect and describe the process as "shedding". Although this phenomenon demonstrates that minoxidil is indeed affecting hair follicles, manufacturers offer no guarantee that the new hair loss will be replaced with hair growth. The speculated reason for this shedding is the encouragement of hairs already in the telogen phase to shed early, before often beginning a fresh, healthier anagen phase.
Minoxidil is highly toxic to cats and may cause death with inadvertent skin contact.
Application
Minoxidil needs to be applied once or the recommended twice daily, and must be used indefinitely for continued support of existing hair follicles and the maintenance of any experienced hair regrowth. To achieve maximum effect, the solution should be in contact with the scalp for at least 4 hours before allowing hair to get wet. Minoxidil stimulates hair follicles and growth, but does not reduce DHTDihydrotestosterone
Dihydrotestosterone is an androgen or male sex hormone. The enzyme 5α-reductase synthesises DHT in the prostate, testes, hair follicles, and adrenal glands...
or the enzyme responsible for its accumulation around the hair follicle, 5-alpha reductase
5-alpha reductase
5α-reductases, also known as 3-oxo-5α-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in 3 metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism, and prostate cancer....
, which is the primary mediator of male pattern baldness in genetically susceptible individuals. Therefore, when treatment is stopped, the DHT
Dihydrotestosterone
Dihydrotestosterone is an androgen or male sex hormone. The enzyme 5α-reductase synthesises DHT in the prostate, testes, hair follicles, and adrenal glands...
has its expected effect of shrinking and ultimately destroying the genetically predisposed hair follicles.
Minoxidil solutions are sold under many brand names. Many high priced as well as generic brands of minoxidil regrowth solutions exist and do not differ in their active ingredient or concentration. Minoxidil products involve contact with hair strands which may cause problems with hair styling as minoxidil must be in an alcohol-based solution. If the solution does not pose any issues, hair styling products may be applied after it has dried.