Studies of metabolism and disposition of potent human immunodeficiency virus (HIV) integrase inhibitors using ¹⁹F-NMR spectroscopy

Abstract

¹⁹F-nuclear magnetic resonance (NMR) has been extensively used in a drug-discovery programme to support the selection of candidates for further development. Data on an early lead compound, N-(4-fluorobenzyl)-5-hydroxy-1-methyl-2-(4-methylmorpholin-3-yl)-6-oxo-1,6-dihydropyrimidine-4-carboxamide (compound A (+)), and MK-0518 (N-(4-fluorobenzyl)-5-hydroxy-1-methyl-2-(1-methyl-1-{[(5-methyl-1,3,4-oxadiazol-2-yl)carbonyl]amino}ethyl)-6-oxo-1,6-dihydropyrimidine-4-carboxamide), a potent inhibitor of this series currently in phase III clinical trials, are described. The metabolic fate and excretion balance of compound A (+) and MK-0518 were investigated in rats and dogs following intravenous and oral dosing using a combination of ¹⁹F-NMR-monitored enzyme hydrolysis and solid-phase extraction chromatography and NMR spectroscopy (SPEC-NMR). Dosing with the ³H-labelled compound A (+) enabled the comparison of standard radiochemical analysis with ¹⁹F-NMR spectroscopy to obtain quantitative metabolism and excretion data. Both compounds were eliminated mainly by metabolism. The major metabolite identified in rat urine and bile and in dog urine was the 5-O-glucuronide.

Key Words::

• Human immunodeficiency virus (HIV) integrase inhibitors
• 19F-nuclear magnetic resonance (NMR) spectroscopy
• N-methylpyrimidone metabolism
• glucuronidation

Acknowledgements

The authors thank Odalys Gonzalez-Paz, Fabio Bonelli, Francesca Naimo, Maria Verdirame, and Massimiliano Fonsi for pharmacokinetics and analytical support. They also thank Frank Tang (Merck Research Laboratories, Rahway, NJ, USA) for radiochemical synthesis of tritiated compound A (+). This work was supported in part by a grant from the Ministero dell’Istruzione, dell’Università e della Ricerca.