Retinoid are a class of drugs that are vitamiers of vitamin A or are chemically related to it. It is used primarily due to the way they regulate epithelial cell growth.

• It has many important and diverse functions throughout the body including roles in vision, regulation of cell proliferation and differentiation, growth of bone tissue, immune function, and activation of tumor suppressor genes

There are 3 generations of retinoids:

• 1st generation retinoids, including:
  • Retinol
  • Retinal
  • Tretinoin (retinoic acid, Retin-A)
  • Isotretinoin
  • Alitretinoin
• 2nd generation retinoids, including:
  • Etretinate, and its metabolite, acitretin
• 3rd generation retinoids, including:
  • Tazarotene
  • Bexarotene
  • Adapalene