Patients on drug therapy causing immunosuppression 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. Side effects like diarrhoea, nausea and vomiting may potentially be porphyrinogenic through reduction in carbohydrate intake.

Infections are common in patients using immunosuppressants and 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 everolimus that can be confused with an acute porphyric attack are diarrhoea, vomiting, and nausea. These side effects may potentially be porphyrinogenic if leading to a decrease in carbohydrate intake.

Everolimus is not a mechanism based inhibitor of CYP3A4 or CYP2C9, and there are no signs of relevant in vivo induction of the liver drug metabolizing enzymes. No pharmacokinetic porphyrinogenic effects are suspected.

Everolimus is a hydroxyethyl derivative of rapamycin, which is a macrolide, isolated from the micro-organism Streptomyces hygroscopicus.

Everolimus is an antineoplastic agent indicated for the treatment of patients with advanced renal cell carcinoma, neuroendocrine tumors of pancreatic origin and hormone receptor-positive advanced breast cancer. It is also used as a proliferation signal inhibitor in the prevention of graft rejection episodes in patients undergoing renal or cardiac transplantation as part of an immunosuppressive regimen that includes ciclosporin (microemulsifying) and corticosteroids. It is administered orally.

The major enzyme responsible for the oxidative metabolism of everolimus in human liver microsomes was CYP3A4. Everolimus has shown to be a competitive inhibitor of the CYP3A4 and a mixed inhibitor of the CYP2D6. Everolimus has little or no effect on the metabolism of paclitaxel, tolbutamide and s-mephenytoin by CYP2C8, CYP2C9 and CYP2C19, respectively. There were no signs of relevant in vivo induction of the liver drug metabolizing enzymes by everolimus, although no data from hepatocytes were available.