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

F-19-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-l-methyl-2-(4-methylmorpholin-3-yl)-6-oxo-1,6-dihydropyrimidine-4- carboxamide (compound A (+)), and MK-0518 (N-(4-fluorobenzyl)-5-hydroxy-l-methyl-2-(Imethyl- -1-{[(5-methyl-1,3,4-oxadiazol-2-yl)carbonyll amino} ethyl)-6-oxo- 1,6-dihydropyrimidine-4-ca rboxamide), 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 F-19-NMR-monitored enzyme hydrolysis and solid-phase extraction chromatography and NMR spectroscopy (SPEC-NMR). Dosing with the 3 H-labelled compound A (+) enabled the comparison of standard radiochemical analysis with F-19-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.