Twelfth-Position Deuteration of Nevirapine Reduces 12-Hydroxy-Nevirapine Formation and Nevirapine-Induced Hepatocyte Death

Cytochrome
P450-dependent metabolism of the anti-HIV drug nevirapine
(NVP) to 12-hydroxy-NVP (12-OHNVP) has been implicated in NVP toxicities.
We investigated the impact of twelfth-position trideuteration (12-D3NVP) on the hepatic metabolism of and response to NVP. Formation
of 12-OHNVP decreased in human (10.6-fold) and mouse (4.6-fold) hepatocytes
incubated with 10 μM 12-D3NVP vs NVP. An observed
kinetic isotope effect of 10.1 was measured in human liver microsomes.
During mouse hepatocyte treatment (400 μM) with NVP or 12-D3NVP, cell death was reduced 30% with 12-D3NVP vs
NVP, while glucuronidated and glutathione-conjugated metabolites increased
with 12-D3NVP vs NVP. Using mass spectrometry proteomics,
changes in hepatocyte protein expression, including an increase in
stress marker insulin-like growth factor-binding protein 1 (IGFBP-1),
were observed with 12-D3NVP vs NVP. These results demonstrate
that while deuteration can reduce P450 metabolite formation, impacts
on phase II metabolism and hepatocyte protein expression should be
considered when employing deuteration to reduce P450 metabolite-related
hepatotoxicity.