1 INDICATIONS AND USAGE

1.1 Plaque Psoriasis

Tazarotene gel, 0.05% and 0.1% are indicated for the topical treatment of patients with plaque psoriasis of up to 20% body surface area involvement.

1.2 Acne Vulgaris

Tazarotene gel, 0.1% is also indicated for the topical treatment of patients with facial acne vulgaris of mild to moderate severity.

The efficacy of tazarotene gel in the treatment of acne previously treated with other retinoids or resistant to oral antibiotics has not been established.

1.3 Limitations of Use

The safety of tazarotene gel use on more than 20% body surface area has not been established in psoriasis or acne [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1)].

2 DOSAGE AND ADMINISTRATION

Tazarotene gel is for topical use only. Tazarotene gel is not for ophthalmic, oral, or intravaginal use. Avoid accidental transfer of tazarotene gel into eyes, mouth, or other mucous membranes. If contact with mucous membranes occurs, rinse thoroughly with water [see Warnings and Precautions (5.2)].

Wash hands thoroughly after application.

2.1 Psoriasis

It is recommended that treatment starts with tazarotene gel, 0.05%, with strength increased to 0.1% if tolerated and medically indicated. Apply a thin film (2 mg/cm2) of tazarotene gel once per day, in the evening, to cover only the psoriatic lesions on no more than 20% of body surface area. If a bath or shower is taken prior to application, the skin should be dry before applying the gel. If emollients are used, they should be applied at least an hour before application of tazarotene gel. Because unaffected skin may be more susceptible to irritation, application of tazarotene to these areas should be carefully avoided. Tazarotene gel was investigated for up to 12 months during clinical trials for psoriasis.

2.2 Acne

Cleanse the face gently. After the skin is dry, apply a thin layer (2 mg/cm2) of tazarotene gel 0.1% once per day, in the evening, to the skin where acne lesions appear. Use enough to cover the entire affected area. Tazarotene gel was investigated for up to 12 weeks during clinical trials for acne. Use effective sunscreens and wear protective clothing while using tazarotene gel [see Warnings and Precautions (5.3)].

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Tazarotene is a retinoid prodrug which is converted to its active form, the carboxylic acid of tazarotene, by deesterification. Tazarotenic acid binds to all three members of the retinoic acid receptor (RAR) family: RARα, RARβ, and RARγ, but shows relative selectivity for RARβ, and RARγ and may modify gene expression. The clinical significance of these findings for the treatment of plaque psoriasis and facial acne vulgaris is unknown.

12.2 Pharmacodynamics

The pharmacodynamics of tazarotene gel in the treatment of plaque psoriasis and facial acne vulgaris are unknown.

12.3 Pharmacokinetics

Following topical application, tazarotene undergoes esterase hydrolysis to form its active metabolite, tazarotenic acid. Little parent compound could be detected in the plasma. Tazarotenic acid was highly bound to plasma proteins (greater than 99%).

Tazarotene and tazarotenic acid were metabolized to sulfoxides, sulfones and other polar metabolites which were eliminated through urinary and fecal pathways. The half-life of tazarotenic acid was approximately 18 hours, following topical application of tazarotene to normal, acne or psoriatic skin.

The human in vivo studies described below were conducted with tazarotene gel applied topically at approximately 2 mg/cm2 and left on the skin for 10 to 12 hours. Both the peak plasma concentration (Cmax) and area under the plasma concentration time curve (AUC) refer to the active metabolite only.

Two single, topical dose studies were conducted using 14C-tazarotene gel. Systemic absorption, as determined from radioactivity in the excreta, was less than 1% of the applied dose (without occlusion) in six subjects with psoriasis and approximately 5% of the applied dose (under occlusion) in six healthy subjects. One non-radiolabeled single-dose study comparing the 0.05% gel to the 0.1% gel in healthy subjects indicated that the Cmax and AUC were 40% higher for the 0.1% gel.

After 7 days of topical dosing with measured doses of tazarotene 0.1% gel on 20% of the total body surface without occlusion in 24 healthy subjects, the Cmax for tazarotenic acid was 0.72 ± 0.58 ng/mL (mean ± SD) occurring 9 hours after the last dose, and the AUC0-24hr for tazarotenic acid was 10.1 ± 7.2 ng·hr/mL. Systemic absorption was 0.91 ± 0.67% of the applied dose.

In a 14-day study in five subjects with psoriasis, measured doses of tazarotene 0.1% gel were applied daily by nursing staff to involved skin without occlusion (8 to 18% of total body surface area; mean ± SD: 13 ± 5%). The Cmax for tazarotenic acid was 12.0 ± 7.6 ng/mL occurring 6 hours after the final dose, and the AUC0-24hr for tazarotenic acid was 105 ± 55 ng·hr/mL. Systemic absorption was 14.8 ± 7.6% of the applied dose. Extrapolation of these results to represent dosing on 20% of total body surface yielded estimates for tazarotenic acid with Cmax of 18.9 ± 10.6 ng/mL and AUC0-24hr of 172 ± 88 ng·hr/mL.

An in vitro percutaneous absorption study, using radiolabeled drug and freshly excised human skin or human cadaver skin, indicated that approximately 4 to 5% of the applied dose was in the stratum corneum (tazarotene: tazarotenic acid = 5:1) and 2 to 4% was in the viable epidermis-dermis layer (tazarotene: tazarotenic acid = 2:1) 24 hours after topical application of the gel.