Minoxidil, a hair loss treatment discovered by accident
How does minoxidil help hair grow?
Minoxidil is actually what's called a prodrug, this means that it is not the active form of the medication. Minoxidil is converted to its active form, minoxidil sulfate, by an enzyme called sulfotransferase.
As a hair restoration therapy, minoxidil prolongs the anagen phase of the growth cycle. This is the phase when the cells in the root of the hair are dividing very quickly.
How to know if minoxidil will work for you?
Not everyone responds to minoxidil. Generally, low enzyme activity in the body will mean that you have a limited response to minoxidil and high enzyme activity means a better response.
One interesting point is that salicylic acid, which is an aspirin precursor, actually inhibits that same enzyme expression in the liver and that's why it should be avoided for optimal efficacy of minoxidil if possible.
Different formulations of minoxidil
- as a topical formulation,
- as an oral medication.
- sublingually
Topical minoxidil
The topical formulation of minoxidil is an FDA-approved drug for the treatment of androgenic alopecia. It's also used off-label in other hair loss disorders including alopecia areata. It comes as either a solution or a foam product and can be used on the head, beard, and eyebrow areas.
The solution has propylene glycol, which improves the delivery of the drug into the hair follicles - but may also cause local irritation.
The foam does not contain propylene glycol, is easier to use because it's quicker to dry, and is more localized in its application making it the more popular choice.
Men with androgenic alopecia are advised to apply either 1 ml of a 5% minoxidil solution or half a capful of a 5% minoxidil foam twice a day. For women with female pattern hair loss, it's recommended to use 1 ml of a 2% solution twice a day or half a capful of a 5% foam once a day.
Side effects of topical minoxidil
Common side effects of topical minoxidil use include:
- irritant contact dermatitis (which includes symptoms such as itching and scaling),
- headaches,
- hypertrichosis (which tends to be worse in women),
- a 3-6 week shedding period (what sheds is old hair and this is due to the growth cycle being induced so don't worry when this happens),
- Undesirable hair texture.
The higher the dosage, the worse and more serious the side effects are.
It is important to point out that, following a four-month long twice-daily application, less than 40% of patients noticed hair re-growth. One reason for this is that not everyone responds to minoxidil. Another reason is that the frequency of application is not tolerable due to the side effects for some people.
Oral minoxidil
Due to the side effects listed above and the fact that approximately 1.4% of the topical solution is actually absorbed, many opt for minoxidil tablets. Doses that have been shown to be effective for women with female pattern hair loss are as low as 0.25 milligrams daily. For men, they can be as low as 1 milligram, but the usual recommended dose, based on various studies, is 2.5-5 milligrams per day.
Side effects of oral minoxidil
Sublingual application of minoxidil
The sublingual application involves taking a minoxidil tablet, putting it under the tongue, and allowing it to dissolve. The advantage of this administration is that it bypasses the hepatic (liver) metabolism and therefore increases the bioavailability of the drug. This means that there's more of the medication working in the body than when it is orally administered.
There was a study on this way of use done in Australia in 2020 that was a retrospective review of 64 men and women. In this study, there were improvements shown based on a global assessment of photographs and hair shedding scales. The side effects that were noted in the study occurred in a relatively small number of patients and included mild hypertrichosis, mild postural dizziness, and mild edema.
The sublingual formulation has an overall good safety profile and seems to be promising, but we need additional studies before the application can be safely recommended.
Which formulation of minoxidil works best?
Sources:
https://www.clarionmedical.com/Clario...
https://www.ishrs-htforum.org/content...
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