Pharmacokinetics of Darolutamide, its Diastereomers and Active Metabolite in the Mouse: Response to Saini NK et al. (2020)

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Author(s): Pirjo Nykänen, Timo Korjamo, Hille Gieschen, Christian Zurth, Mikko Koskinen*

Journal Name: Drug Metabolism Letters

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Abstract:

Background: Saini et al. recently investigated the pharmacokinetics of darolutamide and its diastereomers in vitro and in vivo in Balb/c mice, reporting higher levels of (S,S)-darolutamide than (S,R)-darolutamide following intravenous or oral dosing, and interconversion of (S,R)-darolutamide to (S,S)-darolutamide.

Objective: To present our in vitro and in vivo studies of darolutamide pharmacokinetics in mice, which contrast with the findings of Saini et al.

Methods: Nude male Balb/c mice were orally dosed for 7 days with 25, 50, or 100 mg/kg of darolutamide twice daily. Pharmacokinetic parameters in plasma and tissue samples were assessed by liquid chromatography-tandem mass spectrometry. Metabolism and interconversion of darolutamide and diastereomers was investigated in cryopreserved Balb/c mouse hepatocytes. Protein binding was determined in plasma samples by equilibrium dialysis.

Results and Discussion: At day 7, Cmax was reached 30 min after last dose. Rapid formation and greater exposure of ketodarolutamide versus darolutamide were observed. Plasma exposure of (S,R)-darolutamide was 3–5-fold higher than that of (S,S)-darolutamide. The fraction of unbound keto-darolutamide was almost 6-fold lower than for darolutamide. In mouse hepatocytes, conversion of (S,S)- to (S,R)-darolutamide was observed but conversion of (S,R)- to (S,S)- darolutamide was not detectable. Back-formation of keto-darolutamide to both diastereomers occurred at low levels.

Conclusion: The darolutamide diastereomer ratio changes upon administration in mice and other species, due to interconversion through keto-darolutamide. This is not considered clinically relevant since both diastereomers and ketodarolutamide are pharmacologically similar in vitro. Based on the high protein binding of keto-darolutamide, its contribution in vivo in humans is considered low.

Keywords: Darolutamide, pharmacokinetics, mice, diastereomer, interconversion, metabolism

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(E-pub Ahead of Print)
DOI: 10.2174/1872312814666201112121129
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