Patients on immunosuppressive therapy have an increased risk of infections. Since infections have a potential to trigger acute porphyric attacks vigilance is motivated regarding signs or symptoms of infection and/or possible symptoms of a porphyric attack.

Infections are common in patients using immunosuppressant drugs. Since infections might trigger an acute porphyric attack, vigilance regarding signs and symptoms of an infection and/ or a porphyric attack is recommended. Common adverse reactions of vedolizumab that can be confused with an acute porphyric attack are nausea and vomiting. These side effects may potentially be porphyrinogenic if leading to a decrease in carbohydrate intake.

Vedolizumab is not metabolized by cytochrome P450 enzymes. No pharmacokinetic porphyrinogenic effects are suspected.

Vedolizumab is a humanised IgG1 monoclonal antibody that binds to the human alpha4 beta7 integrin.

Vedolizumab is used in the treatment of adult patients with moderately to severely active ulcerative colitis or Crohns disease. It is administered as an intravenous injection.

The exact elimination route of vedolizumab is not known. Mechanisms for elimination of monoclonal antibodies are not well documented but are reported to include proteolysis by the liver and the reticuloendothelial system, target-mediated elimination and nonspecific endocytosis (Keizer 2010).