Actives 1

• •Implies medicine-like properties in a cosmetic product
• •From regulatory perspective product is either cosmetic or pharmaceutical, not both or in-between
• •FDA explicitly states that it does not recognise ‘cosmeceutical’ as a regulatory category, and ‘cosmeceutical’ is just a marketing term
• ‘Cosmeceutical’ may contain active ingredients but must not be marketed to imply or have actual medical effect(s)
• •concentration of active agent (usually low)
• •potency of active agent (usually low)
• •nature of formulation containing active agent
• •penetration into skin (potentially just local effect) vs. penetration through skin (potentially systemic effect)
• Skin penetration often seems not to be discussed much in relation to cosmeceuticals; when it is mentioned it seems to be penetration into skin
• Natural or synthetic compounds with biological activity similar to Vitamin A
• Vitamin A (all trans-retinol)
• •influence proliferation & differentiation of epithelial cells
• •influence synthetic activities of mesenchymal cells (connective tissue, blood vessels & smooth muscle)
• •some retinoids suppress sebum
• •can modulate effects of immune system
• •stimulate angiogenesis
• •down-regulate carcinogenesis
• •Large number of derivatives, now in 4th generation
• •1st generation simple derivatives of retinol (e.g. retinoic acid), dates back to 1960s
• •Later generations have synthetic analogues of retinol to give better and safer effects
• Mechanism of Action of Retinoids
• •enter cell by passive diffusion
• •bind to specific intracellular proteins
• •transported to nucleus
• •interact with Retinoic Acid Receptor (RAR) or Retinoid X Receptor (RXR)
• •retinoid – receptor complex activates genes and causes protein synthesis
• •various positive & negative feedback mechanisms in cell
• •metabolism of various retinoids also occurs in cells
• •RA = retinoic acid; RARE = Retinoic Acid Response Element
• Cellular Effects of Retinoids 1
• •down-regulation of psoriatic epidermis
• •reduce size of sebaceous gland and amount of sebum production (isotretinoin)
• •reduce degradation of collagen (all-trans & 13-cis retinoic acid)
• •may increase production of melanin, but decrease number of melanocytes
• •numerous effects on immune system, generally to stimulate it
• Treatment of cancer
• •may have some preventative effect (trials on premalignant lesions)
• Skin photoaging (tretinoin):
• •induces proliferation of epidermis and compact stratum corneum
• •deposition of glycosaminoglycans and collagen in dermis