Experience has shown that some retinoids can influence the speed of hair growth, extending the anagen phase and shortening the telogen phase. These drugs independently stimulate hair growth, and also increase the clinical effectiveness of minoxidil. With the combined external use of tretinoin (0.025% and 0.05%) and minoxidil (1% and 2%), the trichogenic effect of tretinoin increases, but the excretion of minoxidil by the kidneys triples. Special studies have shown that despite an increase in the concentration of the drug in the urine, its plasma level did not increase, and there was no overall hypotensive effect. At the same time, it was noted that combined external therapy with retinoids and minoxidil caused a significant reduction in salofission.
Interesting data were obtained by comparing different schemes of external therapy of patients with normal alopecia. Five equivalent groups of patients, 25 each each, used one of the following treatment regimens: tretinoin; minoxidil; minoxidil + tretinoin; triamsinolone acetate; tretinoin + triamsinolone acetate.
It has been convincingly shown that tretinoin significantly enhances the trichogenic effect of minoxidil and triamsinolone. The combination of tretinoin and triamsinolone was the most effective. None of the studies recorded the absorption of retinoids and their systemic effect.
Later local action of other retinoids, in particular, 13-cis-retinoic acid (isotretinoin) was tested. Densitometry showed a significant decrease in salutation (an average of 49%) in the isotretinoin application areas. The production of dihydrotestosterone i in the skin of the scalp also significantly decreased (by 39.4% compared to baseline data.) Hair count at 9 months of therapy showed the best results in the group of patients receiving combined treatment (isotretinoin and minoxidil) compared to patients with changed only isotretinoin.
Tretinoin (Airol, Locacid, Retin-A) is released in a concentration of 0.1% -0.05% in the form of a solution, gel and cream; isotretinoin (Retinoic ointment) - concentration of 0,01% -0,05% in the form of ointment. Drugs are applied to the dry skin surface once a day.
Side effects. After applying the drugs, a brief sensation of warmth and / or a burning sensation is possible. Local irritation in the form of a slight reddening of the skin can persist until 5-6 weeks of treatment. With more pronounced manifestations of simple dermatitis, drugs should be applied less often. Since retinoids have a photosensitizing effect, during the treatment it is necessary to avoid insolation and irradiation with artificial UV.
Contraindications are hypersensitivity to retinoids and pregnancy (due to the likelihood of teratogenic action).
The 5a-reductase inhibitor, successfully used in the treatment of prostatic adenoma, is able to prevent the development of normal alopecia. Promising results of its topical application (4-MA-4, N-diethyl-4-methyl-3-oxo-4-aza-5a-androstane-17b-carboxumide) were obtained in short-tailed macaques. Prolonged (27 months) daily use of 4-MA, a local 5a-reductase inhibitor, at a dose of 14 mg / ml in DMSO prevented hair loss in monkeys that did not reach the genital; maturity; while in the control group, loss of hair of varying severity was observed.
Thus, for the treatment of normal alopecia, in addition to the solution of minoxidil and its analogues, 5a-reductase inhibitors can be used as an adjuvant. It should be emphasized that the results of their clinical trials in humans have not yet been published.
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