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. Side effects like 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 azathioprine 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.

Azathioprine is exclusively or predominately metabolized by other enzymes than CYP, and is not known to affect the activity of any CYP enzymes. Based on the pharmacokinetics, azathioprine is not expected to have any porphyrinogenic effects.

Nitroamidazolpurine, an imidazol derivative of mercaptopurine.

Azathioprine is an immunosuppressant used in the prevention of transplant rejection, and it is also used in autoimmune diseases. It is administered orally or as an intravenous injection

Azathiporine is converted to 6-mercaptopurine via a non-enzymatic process, and subsequently metabolized to inactive metabolites by xanthine oxidase and thiopurine S-methyltransferase respectively, and to the active 6-thioguanin nucleotides by hypoxantin-guanin phosphoribosyltransferase.

Found to accumulate porphyrins in chicken embryo model (Cochon et al 1997).

Reports of uneventful use: Warholm et al 2003 (tolerated in 1 patient with AIP). Nunez et al 1987 (tolerated in 1 patient with AIP and in 1 patient with VP) Day et al 1982 (tolerated in 1 patient with VP)

Uneventful use reported in 2 patients with acute porphyria.