Non-CYP metabolism. Reported to be tolerated by 5 patients with AIP. Side effects such as nausea, vomiting and anorexia may be potentially porphyrinogenic through reduction in caloric intake.

Fluorouracil is an analogue of the pyrimidine uracil.

Fluorouracil is used for the palliative treatment of carcinoma of the colon, rectum, breast, stomach, and pancreas that is not amenable to surgery or irradiation. The drug also is used as an adjunct to surgery for the treatment of various solid tumors (e.g., adenocarcinoma of the colon, rectal carcinoma, or breast cancer)Administered as as an intravenous injection or infusion. Common adverse reactions of fluorouracil that can be confused with an acute porphyric attack are nausea, vomiting, diarrhoes,and cerebral ataxia. Side effects such as nausea, vomiting and anorexia may be potentially porphyrinogenic through reduction in caloric intake.

Fluorouracil is metabolized by dihydropyrimidine dehydrogenase, a non-CYP enzyme (Collins, J. M., 2000). Baumhakel et al (2001) states that fluorouracil has no inhibitory effect on CYP3A4. No observations pointing to clinical CYP-induction. Rendic (2002) reports fluorouracil to be a substrate for several smaller CYP-groups (1A2,2A6, 2C8, 2E1, 3A5), but not an inducer or inhibitor. In spite of reports of fluorouracil leading to increased effect of warfarin, Park et al found that fluorouracil has no inhibitory effect on CYP-isoforms or drug metabolism causing drug interaction with fluorouracil, and concludes that the mechanism that causes drug interaction may not be related to direct CYP-inhibition by fluorouracil.

Samuels et al (1984) reported unevenful use of 5-fluorouracil in 2 patients with VP. De Wet (1992) reported uneventtful use in a 56 year old woman with quiescent VP.

Uneventful use reported twice in male VP patient, baseline PBG level was measured and then daily monitoring for a few days and then weekly until finished chemotherapy without any increase in PBG levels. Uneventful use reported in 62 year-old AIP female.