The May 5, 2008 article (Med Lett Drugs Ther 2008; 50:34) on the approval of natalizumab (Tysabri) for treatment of Crohn's disease in the "Adverse Effects" section on page 35 included the statement: "post-marketing hepatotoxicity, sometimes fatal or requiring liver transplantation, has occurred." Actually, no fatal hepatotoxicity or liver transplantation has been reported to date. The FDA warning about post-marketing hepatotoxicity with Tysabri that was the basis for our statement said: "The combination of transaminase elevations and elevated bilirubin without evidence of obstruction is...

Psoriatic arthritis is a chronic inflammatory arthropathy associated with psoriasis. A recent review found that about 20% of patients with psoriasis have psoriatic arthritis. Updated guidelines for treatment of psoriatic arthritis have recently been published.

In the Medical Letter article on ustekinumab (Stelara) for psoriasis (2010; 52:7), footnote 2 in table 2 should have included a second sentence: $5595.60 is the cost of one 45-mg syringe.

Ulcerative colitis (UC) and Crohn's disease (CD), referred to collectively as inflammatory bowel disease (IBD), are chronic immune-mediated inflammatory conditions. Guidelines for treatment of UC and CD have been updated in recent years

Mild to moderate plaque psoriasis can be treated with topical drugs and phototherapy. Patients with moderate to severe disease generally require systemic therapy. Guidelines for the treatment of psoriasis with topical therapy, phototherapy, and systemic drugs have recently been published.

Some tumor necrosis factor (TNF) inhibitors are being promoted on the internet directly to the public for use in psoriasis (www.yahoo.com).

Rituximab (Rituxan - Genentech), an anti-CD20 monoclonal antibody already marketed for treatment of B-cell non-Hodgkin's lymphoma, is now FDA-approved for use concurrently with methotrexate to treat moderate to severe rheumatoid arthritis in patients who have had an inadequate response to one or more tumor necrosis factor (TNF) inhibitors. Rituximab selectively depletes CD20+ B cells, which apparently play a role in the autoimmune response and in the chronic synovitis associated with rheumatoid arthritis.

The injectable interleukin (IL)-23 antagonist risankizumab-rzza (Skyrizi – Abbvie), previously approved by the FDA for treatment of Crohn's disease (CD), has now been approved for treatment of moderately to severely active ulcerative colitis (UC) in adults. Risankizumab is the first IL-23 antagonist to be approved for treatment of both CD and UC. It is also approved for treatment of plaque psoriasis and psoriatic arthritis.

Rheumatoid arthritis (RA) is prevalent in 0.5% of adults in the US; it is about 2.5 times more common in women than in men. Guidelines for treatment of RA from the American College of Rheumatology were recently updated. The goal of treatment is to minimize disease activity and prevent irreversible joint damage.

Tuberculosis (TB) is still a common cause of death worldwide, and the prevalence of drug-resistant TB poses challenges to its treatment and control. Guidelines with detailed management recommendations are available from the American Thoracic Society, Centers for Disease Control and Prevention (CDC) and Infectious Diseases Society of America (IDSA).