Acitretin is a once-daily oral retinoid agent that is supplied in 10 mg and 25 mg capsules for treatment of adults with severe psoriasis, including plaque, erythrodermic, pustular, guttate and palmar-plantar. Acitretin is the only oral once-a-day medication that is approved by the United States Food and Drug Administration for both initial and maintenance treatment of severe psoriasis in adults.

Lead investigator Jennifer Cather, MD, Dermatologist, Texas Dermatology Associates, Dallas, Texas, United States, noted that current practice in acitretin treatment is to give a maximum tolerable dose, ranging from 25 mg to 50 mg per day, while managing the dose-related adverse effect profile. She said the results of this study are significant because they suggest that dosing at the minimal, more tolerable daily dosing regimen of 10 or 25 mg over a 6-month period is as effective as current practice.

The phase 4, multicenter, open-label, randomized study evaluated the long-term efficacy of a lower dosage of acitretin in 77 patients with psoriasis.

The investigators randomized 38 subjects to receive 25 mg/day of acitretin for 24 weeks and 39 subjects to 25 mg/day of acitretin for 12 weeks followed by a "step down" dosing regimen of 10 mg/day for 12 weeks (n=39). In all patients, the drug was administered with food.

The primary efficacy endpoints evaluated at weeks 12 and 24 included an Overall Lesional Assessment (OLA) score of 0 or 1 (none or minimal), and Psoriasis Area and Severity Index (PASI) reduction of 50% and 75%. The secondary efficacy endpoint included a Subject's Global Assessment (SGA) score of 0 or 1 (none or minimal).

Dose reduction was allowed at weeks 0-24 at the investigators' discretion, and dose increases up to 35 mg were allowed at week 12 if a subject failed to achieve 2 grades of improvement or more in OLA score.

Evaluations for efficacy and safety took place at baseline, and at weeks 2, 4, 8, 12, 20, and 24).

The daily mean dose from baseline to week 12 was 25 ±2 mg in the 25 mg group and 25 ±1 mg in the 25 mg/10 mg group. The daily mean dose between week 12 and 24 was 26 ±4 mg in the 25 mg group and 16 ±10 mg in the 25 mg/10 mg group.

Both treatment groups showed progressive improvements at 12 and 24 weeks, as evaluated by OLA. At week 12, 18% of patients had none to minimal psoriasis and at week 24, 45% of patients in the 25 mg group, and 49% in the 25 mg/10 mg group had none to minimal psoriasis. Overall PASI 50 and PASI 75 response rates at week 12 were 38% and 14%, respectively.

With continued acitretin treatment, PASI 50 and PASI 75 response rates increased both in patients maintaining the 25 mg dose and in patients whose dose was decreased to 10 mg after week 12. In both treatment groups, the percentages of patients reporting an OLA score of 0 or 1 at week 12 and week 24 were similar to investigators' scores.

Adverse effects did not differ significantly between the two treatment groups.

The study was supported by Connetics Corporation.


[Presentation title: Efficacy and Safety of Low-Dose Acitretin for the Treatment of Moderate to Severe Plaque-Type Psoriasis. Abstract P2877]

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