Metabolic activation of flunitrazepam via nitroreduction mediated by aldo-keto reductase 1C3. (PubMed, Drug Metab Dispos)
We screened 6 nitro-containing drugs (flunitrazepam, clonazepam, nimesulide, nilutamide, flutamide, and chloramphenicol) as substrates against recombinant human AKR1C1, AKR1C2, AKR1C3, and AKR1C4, using discontinuous enzymatic assays. We conclude that both AKR1C3 and AKR1C2 may have an important role in flunitrazepam drug response. SIGNIFICANCE STATEMENT: Aldo-keto reductase (AKR)1C3 reduces flunitrazepam to 7-amino-flunitrazepam through the formation of reactive nitroso and hydroxylamino intermediates, and by inhibiting AKR1C2, flunitrazepam may reduce the formation of the neuroactive steroid allopregnanolone.