Hair loss in men and women, known scientifically as androgenetic alopecia (AGA), is a disease that, in addition to its aesthetic impact, can profoundly affect emotional well-being. Research typically associates the condition with a drop in self-esteem, anxiety and worsening quality of life.
Recently, a team of researchers from China and Australia developed an innovative and creative way of applying a medicine that has been known for decades to treat baldness — the minoxidil —, used until now as a lotion or topical foam on the scalp.
the study does not question the effectiveness of the famous vasodilator, which remains one of the few scientifically proven medications to treat AGA. What the researchers did was try to improve the way the medicine is absorbed by the skin.
I mean, minoxidil works, but some of it is lost or does not penetrate hair follicles well when applied as a lotion. This is where the study’s proposal comes into play: microneedling, an unprecedented complementary treatment that uses tiny needles so small that they are barely felt in the skin.
And the big secret that allows these microneedles to pass through the skin without causing pain — and release minoxidil directly into the follicles — is in their chemical composition: stevioside, a natural compound extracted from the stevia plant, which we use, in its industrialized version, to sweeten coffee.
How did scientists decide to mix minoxidil with stevia?
but it follows a chemical and pharmacological logic: in addition to the ability to form solid microneedles that dissolve in the skin, stevioside is an amphiphilic molecule, that is, it can form micelles to dissolve minoxidil.
Micelles are like intelligent bubbles of small molecules called amphiphiles, with two parts: one hydrophilic, which likes water; and another hydrophobic that avoids water. Once in the water, they organize themselves: the hydrophobic ones are in the center of the bubble, and the hydrophilic ones, facing outwards.
A common example of micelles are shampoos, in which the hydrophobic part traps dirt and oil in the hair, while the “water-friendly” part stays out, allowing for easy rinsing. The same reasoning applies to kitchen detergents, where grease from dishes is easily removed by water.
In the situation proposed in the study, the micelles formed by stevioside “embrace” the minoxidil molecules, which do not mix well with water. In this way, the medicine is able to travel “on board” the micelles, which break down in the moist environment of the skin. and release minoxidil exactly where it needs to act.
The interaction of the micelle with water creates a structure that is, at the same time, soluble and stable in the aqueous medium. In this way, the hydrophobic core protects the minoxidil — which is insoluble — while the hydrophilic outer layer allows the entire micelle to mix completely with the solution. The next step was to test all of this.
What were the first tests of minoxidil needles like?
To make the application more practical than current medicines, which run, drip and leave residue, the authors opted for a more sophisticated system: a dissolvable microneedles patch, in which the minoxidil and stevioside micelles themselves form the material for the microstructures, in a patch of 10 x 10 pyramidal tips.
Although rigid enough to open microchannels in the skin, these little needles do not cause pain and, once inserted, . The method is minimally invasive, reduces waste and ensures accurate delivery.
To prove its effectiveness, the researchers tested the patch’s ability to release minoxidil and make it penetrate the skin. The experiment used the skin of a pig’s ear, which is very similar to the human organ. More than 85% of the medicine crossed the skin surface, and 20% remained trapped in the skin.
But the ultimate test—hair growth—was performed on male rats with alopecia induced by testosterone injections. The rodents were divided into four groups: no treatment, stevioside-only patch, standard 2% minoxidil, and the new STV-MXD microneedle patch.
The results surprised the team: within two weeks the mice with STV-MXD were already showing visible hair growth, and, after 35 days, 67.5% of the treated area was covered by dark hairs. Classic minoxidil, on the other hand, generated only 25.7% coverage, confirming the superiority of the patch.
“The use of stevioside to improve the delivery of minoxidil represents a promising step towards more effective and natural treatments for hair loss, potentially benefiting millions around the world,” he concluded in a statement.
