retinoider

Retinoider, in English typically called retinoids, are a family of chemical compounds related to vitamin A that interact with cellular receptors to regulate gene expression. They encompass natural metabolites such as all-trans retinoic acid and synthetic or semi-synthetic compounds including isotretinoin, tretinoin, adapalene, tazarotene, bexarotene, and acitretin. Retinoids can be used topically or systemically, depending on the condition being treated.

Mechanism of action involves binding to nuclear receptors known as retinoic acid receptors (RARs) and, in some cases, retinoid X receptors (RXRs). The ligand–receptor complexes bind to retinoic acid response elements in DNA, leading to changes in transcription. The downstream effects include normalization of keratinocyte differentiation, reduction of hyperkeratosis, anti-inflammatory actions, and modulation of sebum production. These actions underlie their varied therapeutic applications for skin disorders and certain cancers.

Clinical uses span dermatology and oncology. In dermatology, topical retinoids are widely used for acne to normalize desquamation and reduce comedones, and they are employed for photoaged skin and certain inflammatory conditions such as psoriasis. Systemic retinoids like acitretin are used for severe psoriasis and some ichthyoses, while isotretinoin remains a mainstay for severe nodular acne. In oncology, all-trans retinoic acid is a standard treatment for acute promyelocytic leukemia, where it promotes differentiation of malignant cells; bexarotene is used for certain cutaneous T-cell lymphomas.

Safety concerns include skin irritation and dryness with topical forms, photosensitivity, and teratogenic risk with systemic retinoids. Systemic retinoids require careful monitoring of liver function and lipid levels, and strict pregnancy prevention measures.