Obagi System-Tretinoin Gel 0.025%

Tretinoin Cream 0.025%, .05% and .1% Stimulates renewal of healthy skin cells. (Rx only) 15 gm

Tretinoin Description Tretinoin Cream, USP (Emollient) 0.05% contains the active ingredient Tretinoin in a cream base. Tretinoin is a yellow-to-light-orange crystalline powder having a characteristic floral odor. Tretinoin is soluble in dimethylsulfoxide, slightly soluble in polyethylene glycol 400, octanol, and 100% ethanol. It is practically insoluble in water and mineral oil, and it is insoluble in glycerin. The chemical name for Tretinoin is (all-E)-3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclonexen-1-yl)-2,4,6,8-nonatetraenoic acid. Tretinoin is also referred to as all-trans-retinoic acid and has a molecular weight of 300.44. The structural formula is represented below. Tretinoin is available as Tretinoin Cream, USP (Emollient) at a concentration of 0.05% w/w in a water-in-oil emulsion formulation consisting of butylated hydroxytoluene, citric acid monohydrate, dimethicone 50 cs, edetate disodium, fragrance, hydroxyoctacosanyl hydroxystearate, light mineral oil, methoxy PEG-22/dodecyl glycol copolymer, methylparaben, PEG-45/dodecyl glycol copolymer, purified water, quaternium-15, stearoxytrimethylsilane and stearyl alcohol, and sorbitol solution. Tretinoin - Clinical Pharmacology Tretinoin is an endogenous retinoid metabolite of Vitamin A that binds to intracellular receptors in the cytosol and nucleus, but cutaneous levels of Tretinoin in excess of physiologic concentrations occur following application of a Tretinoin-containing topical drug product. Although Tretinoin activates three members of the retinoic acid (RAR) nuclear receptors (RARa, RARb, and RARg) which may act to modify gene expression, subsequent protein synthesis, and epithelial cell growth and differentiation, it has not been established whether the clinical effects of Tretinoin are mediated through activation of retinoic acid receptors, other mechanisms such as irritation, or both. The effect of Tretinoin on skin with chronic photodamage has not been evaluated in animal studies. When hairless albino mice were treated topically with Tretinoin shortly after a period of UVB irradiation, new collagen formation was demonstrated only in photodamaged skin. However, in human skin treated topically, adequate data have not been provided to demonstrate any increase in desmosine, hydroxyproline, or elastin mRNA. Application of 0.1% Tretinoin cream to photodamaged human forearm skin was associated with an increase in antibody staining for procollagen I propeptide. No correlation was made between procollagen I propeptide staining with collagen I levels or with observed clinical effects. Thus, the relationships between the increased collagen in rodents, increased procollagen I propeptide in humans, and the clinical effects of Tretinoin have not yet been clearly defined. Tretinoin was shown to enhance UV-stimulated melanogenesis in pigmented mice. Generalized amyloid deposition in the basal layer of Tretinoin-treated skin was noted in a two-year mouse study. In a different study, hyalinization at Tretinoin-treated skin sites was noted at doses beginning at 0.25 mg/kg in CD-1 mice. The transdermal absorption of Tretinoin from various topical formulations ranged from 1% to 31% of applied dose, depending on whether it was applied to healthy skin or dermatitic skin. When percutaneous absorption of Tretinoin Cream, USP (Emollient) 0.05% was assessed in healthy male subjects (n=14), as well as after repeated daily applications for 28 days, the absorption of Tretinoin was less than 2% and endogenous concentrations of Tretinoin and its major metabolites were unaltered.