Differin Lotion

Apply a thin film of Differin Lotion to the entire face and other affected areas of the skin once daily, after washing gently with a mild soapless cleanser. Dispense a nickel size amount of Differin Lotion (3-4 actuations of the pump) to cover the entire face. Avoid application to the areas of skin around eyes, lips and mucous membranes. Differin Lotion is for topical use only and not for oral, ophthalmic, or intravaginal use.

Mechanism of Action

Adapalene binds to specific retinoic acid nuclear receptors but does not bind to cytosolic receptor protein. Biochemical and pharmacological profile studies have demonstrated that adapalene is a modulator of cellular differentiation, keratinization and inflammatory processes. However, the significance of these findings with regard to the mechanism of action of adapalene for the treatment of acne is unknown.

Pharmacodynamics

Pharmacodynamics of Differin Lotion is unknown.

Pharmacokinetics

Systemic exposure of adapalene following a topical application of Differin Lotion was studied in two pharmacokinetic (PK) clinical trials. The first trial was conducted in 14 adult subjects 18 to 29 years of age with severe acne and the second trial was conducted in 13 adolescent subjects 12 to 17 years of age with moderate to severe acne.

In each trial, subjects were treated with 2 g of Differin Lotion applied once daily to approximately 1000 cm² of acne involved skin for 28 days (adolescent subjects) or 30 days (adult subjects). Serial plasma samples were collected at 24 or 72 hours following application on days 1, 15 and 28/30.

Daily topical application of Differin Lotion resulted in low systemic exposure to adapalene in the two populations (adult and adolescent subjects).

In the adult population, all plasma concentrations in 12 out of 14 subjects were below the limit of quantification (LOQ=0.1 ng/mL). One subject had one sample above LOQ at day 30 and the other subject had four plasma samples above LOQ on both days 1 and 15, which ranged from 0.102 and 0.131 ng/mL.

In the adolescent population, plasma concentrations were quantifiable (>0.1 ng/mL) in five subjects. On Day 28, the mean Cmax was 0.128 ± 0.049 ng/mL (range: <0.100 to 0.244 ng/mL) and the mean of AUC0-24hr was 3.07 ± 1.21 ng.hr/mL (range: 1.86 to 4.93 ng.hr/mL). Adapalene plasma concentrations in all subjects were below the limit of quantification (<0.1 ng/mL) 48 hours after the last application on Day 28.