We are looking for a formula for Tretinoine 0.5% solution for treatment of "black hair tongue" or "lingua villosa". Is the prescribed concentration not too high and which solvent is suitable?

The treatment of black hair tongue consists of eliminating predispozing factors and a good mouthhygi ë ne. If necessary, the batter can be brushed away with a soft toothbrush. Special toothpaste & #039; s such as Zendium or Paradontax are called. Also brushing with 10% UREUMCR è me or brushing with a 40% solution of urea in water or 0.1% Tretino ï NE solution is an option.
This concentration is the highest, which I could find. The composition reads: Tretino ï ne 100mg, ethanol 94 ° 40.4 G, BHT 50mg, propylene glycol 51.9 g.
an alternative is according to Prof. Delattre: Tretino ï ne 25mg, ethanol 94 ° 25g, Propylene glycol 20g, tocopherol acetate 25mg.
with this solution, the tongue is brushed twice a day.