Risk for gastrointestinal adverse events in the form of abdominal pain, obstipation, diarrhoea, nausea and vomiting motivates vigilance against insufficient intake of food, especially of carbohydrate.

Common side effects that can be potentially porphyrinogenic through reduction in carbohydrate intake and that also can be confused with an acute porphyria attack are abdominal pain, constipation, diarrhoea, nausea and vomiting. Other common side effects are anorexia, insomnia, somnolence, tremor, headache and tachycardia.

Fluvoxamine is a strong inhibitor of CYP1A2 and a moderate/weak inhibitor of CYP2C9 and CYP3A4. In vitro data indicates that it is a reversible inhibitor of CYP3A4, CYP2C9 and CYP1A2.

Fluvoxamine is a selective serotonin reuptake inhibitor and an antidepressant. It is indicated for the treatment of depression and obsessive compulsive disorders.

CYP2D6 and CYP1A2 is the main enzyme metabolising fluvoxamine in vitro (SPC and Spina 2008). Elimination half-life is 17-22 hours. Fluvoxamine is a strong inhibitor of CYP1A2 and CYP2C19 and a moderate/weak inhibitor of CYP2C8, CYP2C9 and CYP3A4 (FDA, Isoherranen 2009, Pelkonen 2008, SPC and Spina 2008). It is listed as a competitive inhibitor of CYP2B6, CYP2C9, CYP2C19 and CYP2D6 in vitro (Pelkonen 2008). Fluvoxamine is listed as a mechanism-based inhibitor of CYP3A4 in vitro (Zhou 2009). However, IC50 and IC50-shift experiments indicate that fluvoxamine is a reversible inhibitor of CYP3A4 and CYP2C9 (Berry 2008). It is also listed as a reversible inhibitor of CYP1A2 in vitro (Polasek 2008).

Fluvoxamine is listed as safe for use in acute porphyria (Moore 1997).

Uneventful use reported in 2 patients with acute porphyria.