THURSDAY, May 15 (HealthDay News) -- The drug ustekinumab has been shown to be a very effective initial and long-term treatment for moderate-to-severe psoriasis in two studies published in this week's issue of The Lancet.

Ustekinumab works by binding to two interleukins, proteins produced by the immune system that mediate inflammatory reactions in diseases like psoriasis. The binding stops the interleukins from reaching their specific receptors on the surface of cells.

"Not only does ustekinumab compare favorably to the best available therapies for psoriasis, the maintenance of response between injections every three months also provides a more convenient regimen than those currently available," Drs. Brenda Bartlett and Stephen Tyring, both with the University of Texas Health Science Center in Houston, wrote in a commentary accompanying the publication of the two studies on ustekinumab.

In the first study, two-thirds of patients with moderate-to-severe psoriasis achieved at least a 75 percent improvement in their skin condition (PASI 75 response) after 12 weeks of following regimens of either 45 milligram doses or 90 milligram doses of ustekinumab. At 40 weeks, 63 percent of those patients on 45 milligram doses were at or above the 75 percent level of improvement; 67 percent of those on the 90 milligram regimen had reached that level.

After 40 weeks, about half the patients achieving the PASI 75 response were randomly selected to stay on maintenance levels of ustekinumab, while the other half stopped using the drug. Over a year, the group on the maintenance dose did much better in retaining their improved psoriasis condition.

"Our results suggest that ustekinumab could be an important therapeutic agent for treating patients with psoriasis... The high level of efficacy was generally maintained with dosing every 12 weeks, a schedule that could offer a novel level of convenience for patients and physicians," the report's authors concluded.

In the second study, researchers found that the higher 90 milligram doses of ustekinumab, when increased from once every 12 weeks to once every eight weeks, were effective at helping moderate-to-severe psoriasis patients who had only partially reached the desired 75 percent while taking lower or less frequent doses.

"Although treatment with ustekinumab every 12 weeks is effective for most patients with moderate-to-severe psoriasis, intensification of dosing to once every eight weeks with ustekinumab 90 milligram might be necessary to elicit a full response in patients who only partially respond to the initial regimen," the authors concluded.

More information

The National Psoriasis Foundation has more about psoriasis and its treatment.