The Committee for Medicinal Products for Human Use (CHMP) at European Medicines Agency (EMA) has recommended that ketoconazole tablets, for the systemic treatment of fungal infections, to be taken off the market. This is because of risk for serious hepatic toxicity and that there are other safer alternatives for treatment available. The potential benefits are therefore not considered to outweigh the potential risks.

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, diarrhoea nausea and vomiting. Other common side effects are headache and liver function disturbances. The Committee for Medicinal Products for Human Use (CHMP) at European Medicines Agency (EMA) recommended ketoconazole tablets, for the systemic treatment of fungal infections, to be taken off the market. This is because of risk for serious hepatic toxicity and that there are other safer alternatives for treatment available. The potential benefits are therefore not considered to outweigh the potential risks. Ketoconazole has been reported to form reactive metabolites (Argoti 2005), which are associated with idiosyncratic liver disease (Walsh 2012). One mechanism behind drug induced liver injury is thought to be direct mitochondrial impairment (Russmann 2009). Reactive metabolites are thought to uncouple or inhibit the mitochondrial respiratory chain causing reduced β-oxidation and ATP depletion in the liver cells (Au 2011). In theory, the low-energy status of the liver cells may in turn activate the heme-biosynthesis, thus being potentially porphyrinogenic.

Ketoconazole is a potent inhibitor of CYP3A4 in vivo and has been shown to be a reversible inhibitor in vitro. Ketoconazole is associated with risk of serious liver injury, which might be due to a reduced capacity in ATP generation. This low-energy state may potentially be porphyrinogenic by activating the heme biosynthesis.

Ketoconazole is an antimycotic for systemic use. It is an imidazole derivative.

Ketoconazole is indicated for the treatment of fungal infections of the skin and hair, which cannot be treated topically, and in patients resistant to or intolerant of other treatments. Ketoconazole is also indicated for the treatment of endogenous Cushing’s syndrome. It is administered orally. Ketoconazole is contraindicated in patients with acute and chronic liver disease.

Peak plasma concentration was 3.5 µg/ml, which is equivalent to 6.6 µM, following administration of a 200 mg tablet (SPC).

Ketoconazole is metabolised mainly by CYP3A4 (SPC). Ketconazole is listed as a strong inhibitor of CYP3A in vivo (FDA, Isoherranen 2009, Pelkonen 2008 and SPC). The inhibition is non-time-dependent (Li 2001 and von Moltke 2000) and thought to be mixed competitive-noncompetitive in vitro (Greenblatt 2011, Pelkonen 2008). When ketoconazole was co-administered with midazolam it increased the AUC of midazolam significantly 10 times compared with the placebo phase (Olkkola 1994). Concomitant administration of ketoconazole and lurasidone resulted in a 9.4-fold increase in the AUC of lurasidone (Chiu 2014). Another in vivo study also showed that ketoconazole inhibited the CYP3A-mediated metabolism of midazolam (Fuchs 2013). These data confirm that ketoconazole is an inhibitor of CYP3A4. An in vitro study showed that inhibition of testosterone 6β-hydroxlation by ketoconazole was not enhanced by pre-incubation. This indicates that ketoconazole is a reversible inhibitor of CYP3A4 (Greenblatt 2011). Ketoconazole is listed as a weak inhibitor of CYP2C8 and CYP2C19 in vivo (FDA). In vitro data has indicated that ketoconazole is an antagonist of human glucocorticoid receptors, which results in down-regulation of drug metabolizing CYP2C9, CYP3A and several other proteins (Dovorak 2011 and Duret 2006). Other studies also showed that ketoconazole is an inhibitor of hPXR (Huang 2007) and can inhibit xenobiotic-inducible expression of CYP3A4 in vitro (Dvorak 2011 and Wang 2007). However, a drug-drug interaction study with St Johns wort, midazolam and ketoconazole showed that it does not inhibit PXR-mediated induction of CYP3A in vivo (Fuchs 2013).

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