THURSDAY, Feb. 16, 2017 (HealthDay News) -- The injected drug Siliq (brodalumab) has been approved by the U.S. Food and Drug Administration to treat moderate-to-severe plaque psoriasis in adults.

Siliq is approved for patients who've already failed to respond to other systemic therapies, the agency noted.

The autoimmune disease -- so-called because the immune system produces antibodies that attack the body's own tissues -- causes thick, scaly patches of red skin. The drug is designed to inhibit the body's inflammatory response that plays a role in the development of plaque psoriasis, the FDA said in a news release.

The disease occurs most often in people with a family history, usually between ages 15 and 35.

Saliq was evaluated in clinical studies involving more than 4,300 people with moderate-to-severe plaque psoriasis. The most common side effects included joint pain, headache, fatigue, diarrhea, throat pain, nausea, muscle pain and injection-site reactions.

More-serious potential side effects are suicidal thoughts and behavior, especially among people with a history of suicidal behavior or depression, the FDA said. But "a causal association between treatment with Siliq and increased risk of suicidal ideation and behavior has not been established," the agency added.

The drug's label will include a boxed warning of possible suicidal thoughts and behavior, the FDA said. The agency also warned against the drug's use by people with the gastrointestinal disorder Crohn's disease or active tuberculosis.

Siliq is marketed by Valeant Pharmaceuticals, based in Bridgewater, N.J.

More information

The FDA has more about this approval.