A Water‐Soluble Formulation of HET0016 for the In‐Vivo Inhibition of 20‐HETE

Purpose: N‐Hydroxy‐N’‐(4‐butyl‐2‐methylphenyl)‐formamidine (HET0016) is a potent inhibitor of the cytochrome P450 enzymes responsible for the formation of the small vessel vasoconstrictor 20‐Hydroxyeicosatetraenoic acid (20‐HETE). However, HET0016 has a low aqueous solubility, limiting in vivo administration. The aim of this study was to use 2‐hydroxypropyl β‐cyclodextrin (2‐HPβCD) to create a water‐soluble formulation of HET0016. Methods: The water solubility of HET0016 in both ddH 2 O and 15% 2‐HPβCD was determined. Rats then received 15% 2‐HPβCD or a formulation of HET0016 and 2‐HPβCD. Brain cortex, kidney and liver were subsequently analyzed for 20‐HETE content via HPLC/MS‐MS. Additional studies were also performed in order to maximize the amount of HET0016 and minimize the amount of 2‐HPβCD in the formulation. Results: The solubility of HET0016 in ddH 2 O was found to be 34.2μg/mL compared to 452.7μg/mL in 15% 2‐HPβCD. 20‐HETE concentrations for the control group were 38.5, 189.2 and 835ng/g tissue in the brain cortex, kidney and liver, respectively. 20‐HETE concentrations in the same tissues for the experimental group were 9.8, 37.4 and 231.7ng/g tissue, respectively. Optimization of the HET0016:2‐HPβCD formulation showed that the greatest amount of HET0016 present in the smallest percentage of 2‐HPβCD was 1.3mg in 12.5%. Conclusions: 2‐HPβCD increased the water solubility of HET0016 thirteen‐fold and also provided a water‐soluble formulation of this compound. When administered to rats, 20‐HETE formation was inhibited by 74.7% in the brain cortex, by 80.2% in the kidney and by 72.3% in the liver. This work is supported by the NIH.