Flupentixol is metabolised by CYP2D6 and is not listed as inducer or inhibitor of any major CYP enzymes. Risk for gastrointestinal adverse events in the form of obstipation, dyspepsia, vomiting and diarrhoea motivates vigilance against insufficient intake of food, especially of carbohydrate.

Thioxantene derivative. The active isomere is cis-(Z)-flupentixol.

Flupentixol is indicated for the treatment of schizophrenia and other psychoses. 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 obstipation, dyspepsia, vomiting and diarrhoea. Other common side effects are myalgia, headache and tachycardia. A less common side effect is loss of appetite. Abrupt discontinuation of zuclopenthixol may be accompanied by withdrawal symptoms. The most common symptoms are nausea, vomiting, anorexia, diarrhoea, rhinorrhoea, sweating, myalgias, paraesthesias, insomnia, restlessness, anxiety, and agitation. Patients may also experience vertigo, alternate feelings of warmth and coldness, and tremor. Symptoms generally begin within 1 to 4 days of withdrawal and abate within 7 to 14 days (SPC).

Flupentixol is a substrate of CYP2D6 (Hiemke 2012 and Pirmohamed 2003). Cis-(Z)-cisflupentixol is metabolised via sulfoxidation and N-dealkylation and glucuronacidconjugation. None of the metabolites are psychopharmacological active (SPC). Half-life elimination is 35 hours. Flupentixol is not listed as an inducer or inhibitor of any major CYP enzymes (Isoherranen 2009 and Pelkonen 2008).

Thunell: 1 report of uneventful use.

Flupentixol is listed to be unsafe for use in acute porphyria because it has been shown to be porphyrinogenic in animals or in vitro systems (Moore 1997).

Uneventful use reported in 1 patient with acute porphyria.