Zuretinol (QLT091001, 9-cis-retinol) is a retinoid. Retinoids (vitamin A and its analogs) are essential dietary substances that are needed by mammals for reproduction, normal embryogenesis, growth, vision, and maintaining normal cellular differentiation and the integrity of the immune system. Within cells, retinoids regulate gene transcription acting through ligand-dependent transcription factors, the retinoic acid receptors (RARs), and the retinoid X receptors (RXRs). All-trans-retinoic acid binds only to RARs with high affinity, whereas its 9-cis isomer binds with high affinity to both RARs and RXRs. The actions of all-trans- and 9-cis-retinoic acid in regulating cellular responses are distinct and not interchangeable. Zuretinol is a retinal derivative for treatment of visual disorders. It is a synthetic retinoid replacement for 11-cis-retinal. It is an investigational product under development for the treatment of retinal diseases caused by gene mutations that interfere with the availability of 11-cis-retinal. The therapeutic strategy with Zuretinol is to facilitate recovery or restoration of visual function by acting as a replacement for missing 11-cis-retinal and restoring a key biochemical component of the visual (retinoid) cycle. Novelion Therapeutics is currently developing QLT091001 for the treatment of Inherited Retinal Disease caused by retinal pigment epithelium protein 65 (“RPE65”) and lecithin:retinol acyltransferase (“LRAT”) gene mutations, which include Leber Congenital Amaurosis (“LCA”) and Retinitis Pigmentosa (“RP”). QLT091001 has received orphan drug designations for the treatment of LCA (due to inherited mutations in the LRAT and RPE65 genes) and RP (all mutations) by the U.S. Food and Drug Administration (the “FDA”), and for the treatment of LCA and RP (all mutations) by the European Medicines Agency (the “EMA”).

Retinal, All-trans is one of the forms of vitamin A. It is an isomer of 11-cis-retinal, transductor of light into the neural signals. Retinal, All-trans is converted to retinoic acid in vivo by the action of retinal dehydrogenase. Retinal, All-trans is associated with one of the two isoforms of cellular retinol-binding proteins (CRBP-I and CRBP-II). These proteins play important roles in retinoid biology and regulation of the metabolism of retinol and retinal.

Retinyl propionate is a synthetic derivative of a Vitamin A. Upon topical application, retinyl propionate is hydrolyzed by esterases to retinol, which is ultimately converted to retinoic acid. In mouse models, retinyl propionate induced epidermal thickening in mouse tail and promoted collagen formation in UV-irradiated mice. These results encouraged clinical trials of retinyl palmitate against photoaging. Topical retinyl propionate cream (0.15%) did not demonstrate any statistically significant improvement over placebo, but in later studies of combinations of retinyl propionate with climbazole or niacinamide improvements in the appearance of fine lines, wrinkles and age spots were demonstrated.

Retonol, also known as Vitamin A1, is a vitamin found in food and used as a dietary supplement. It is used to treat and prevent vitamin A deficiency. It is also used to prevent further issues in those who have measles. Retinol is used as a metabolic precursor of retinoic acid to treat skin-related conditions, such as cellulite, skin aging, photodamage.

Alitretinoin, or 9-cis-retinoic acid, is a form of vitamin A. It is also used in medicine as an antineoplastic (anti-cancer) agent developed by Ligand Pharmaceuticals. Alitretinoin (9-cis-retinoic acid) is a naturally-occurring endogenous retinoid indicated for topical treatment of cutaneous lesions in patients with AIDS-related Kaposi's sarcoma. Alitretinoin inhibits the growth of Kaposi's sarcoma (KS) cells in vitro. Alitretinoin binds to and activates all known intracellular retinoid receptor subtypes (RARa, RARb, RARg, RXRa, RXRb and RXRg). Once activated these receptors function as transcription factors that regulate the expression of genes that control the process of cellular differentiation and proliferation in both normal and neoplastic cells. In the United States, topical alitretinoin (in the form of a gel; trade name Panretin) is indicated for the treatment of skin lesions in AIDS-related Kaposi's sarcoma.

Alitretinoin, or 9-cis-retinoic acid, is a form of vitamin A. It is also used in medicine as an antineoplastic (anti-cancer) agent developed by Ligand Pharmaceuticals. Alitretinoin (9-cis-retinoic acid) is a naturally-occurring endogenous retinoid indicated for topical treatment of cutaneous lesions in patients with AIDS-related Kaposi's sarcoma. Alitretinoin inhibits the growth of Kaposi's sarcoma (KS) cells in vitro. Alitretinoin binds to and activates all known intracellular retinoid receptor subtypes (RARa, RARb, RARg, RXRa, RXRb and RXRg). Once activated these receptors function as transcription factors that regulate the expression of genes that control the process of cellular differentiation and proliferation in both normal and neoplastic cells. In the United States, topical alitretinoin (in the form of a gel; trade name Panretin) is indicated for the treatment of skin lesions in AIDS-related Kaposi's sarcoma.