Pharmacology: Pharmacodynamics: Mechanism of Actions: Triamcinolone acetonide is a topical corticosteroid which is ranked in the medium potency based on vasoconstrictor assay. It is an adrenocorticosteroid derivative incorporated into a vehicle suitable for application to skin or external mucous membranes. The primary therapeutic effects of topical triamcinolone are due to its anti-inflammatory activity which is non-specific. Topical triamcinolone diffuses across cell membranes to interact with cytoplasmic receptors located in both the dermal and intradermal cells. Triamcinolone appears to induce phospholipase A2 inhibitory proteins (lipocortins) at the cellular level, thus depressing formation, release and activity of the endogenous mediators of inflammation such as prostaglandins, kinins, histamine, liposomal enzymes and the complement system. When triamcinolone is applied to inflamed skin, it inhibits the migration of macrophages and leukocytes into the area by reversing vascular dilation and permeability. The clinical result is a decrease in edema, erythema and pruritus. Topical triamcinolone has an antimitotic effect on epidermal cells by suppressing DNA synthesis.
Dose/concentration/time-pharmacodynamic response relationship: Data is not available.
Mechanism of toxicity: Data is not available.
Pharmacokinetics: Absorption: The amount of triamcinolone absorbed from the skin depends on the intrinsic properties of the vehicle used, the duration of exposure and the surface area and condition of the skin to which it is applied. In general, absorption will be enhanced by increased skin temperature, hydration, application to inflamed or denuded skin, intertriginous areas (e.g., eyelids, groin, axilla) or skin surfaces with a thin stratum corneum layer (e.g., face, scrotum). Palms, soles and crusted surfaces are less permeable. Occlusive dressings greatly enhance skin penetration and, therefore, increase drug absorption.
Infants and children have a higher total body surface to body weight ratio that decreases with age. Therefore, proportionately more topically applied triamcinolone will be absorbed systemically in this population, putting them at a greater risk for systemic effects.
Metabolism: Following topical absorption, triamcinolone enters the systemic circulation and is metabolized in the most tissues but primarily in the liver, to biologically inactive compounds.
Elimination: Inactive metabolites are excreted by the kidneys, primarily as glucuronides and sulfates, but also as unconjugated products. Small amounts of unmetabolized drugs are also excreted in urine.
Occlusive dressings: Occlusive dressings such as a plastic wrap increase skin penetration approximately tenfold by increasing the moisture content of the stratum corneum. Occlusion can be beneficial in resistant cases but it may also lead to sweat retention and increased bacterial and fungal infections. Additionally, increased absorption of triamcinolone may produce systemic side effects. Therefore, do not use occlusive dressings for more than 12 hours per day.