Coupling of liquid chromatography/tandem mass spectrometry and liquid chromatography/solid-phase extraction/NMR techniques for the structural identification of metabolites following in vitro biotransformation of SUR1-selective ATP-sensitive potassium channel openers

Drug Metab Dispos. 2010 Feb;38(2):232-40. doi: 10.1124/dmd.109.028928. Epub 2009 Oct 29.


SUR1-selective ATP-sensitive potassium channel openers (PCOs) have been shown to be of clinical value for the treatment of several metabolic disorders, including type I and type II diabetes, obesity, and hyperinsulinemia. Taking into account these promising therapeutic benefits, different series of 3-alkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides structurally related to diazoxide were developed. In view of the lead optimization process of the series, knowledge of absorption, distribution, metabolism, excretion, and toxicity parameters, and more particularly the metabolic fate of these compounds, is a fundamental requirement. For such a purpose, two selected promising compounds [7-chloro-3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-dioxide (BPDZ 73) and 7-chloro-3-(3-pentylamino)-4H-1,2,4-benzothiadiazine 1,1-dioxide (BPDZ 157)] were incubated in the presence of phenobarbital-induced rat liver microsomes to produce expected mammal in vivo phase I metabolites. The resulting major metabolites were then analyzed by both mass spectrometry (MS) and NMR to completely elucidate their chemical structures. The two compounds were also further incubated in the presence of nontreated rats and human microsomes to compare the metabolic profiles. In the present study, the combined use of an exact mass liquid chromatography (LC)/tandem MS platform and an LC/solid-phase extraction/NMR system allowed the clarification of some unresolved structural assessments in the accurate chemical structure elucidation process of the selected PCO drugs. These results greatly help the optimization of the lead compounds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / metabolism*
  • Animals
  • Benzothiadiazines / metabolism*
  • Chromatography, High Pressure Liquid / methods
  • Cyclic S-Oxides / metabolism*
  • Diazoxide / analogs & derivatives*
  • Diazoxide / metabolism
  • Humans
  • Ion Channel Gating / drug effects*
  • Isomerism
  • KATP Channels / metabolism*
  • Magnetic Resonance Spectroscopy / methods
  • Male
  • Membrane Transport Modulators / metabolism*
  • Metabolic Detoxication, Phase I
  • Microsomes, Liver / metabolism
  • Phenobarbital / pharmacology
  • Potassium Channels, Inwardly Rectifying / metabolism*
  • Protein Isoforms / antagonists & inhibitors
  • Protein Isoforms / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Drug / metabolism*
  • Solid Phase Extraction / methods
  • Sulfonylurea Receptors
  • Tandem Mass Spectrometry / methods


  • 7-chloro-3-(3-pentylamino)-4H-1,2,4-benzothiadiazine 1,1-dioxide
  • 7-chloro-3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-dioxide
  • ABCC8 protein, human
  • ATP-Binding Cassette Transporters
  • Abcc8 protein, rat
  • Benzothiadiazines
  • Cyclic S-Oxides
  • KATP Channels
  • Membrane Transport Modulators
  • Potassium Channels, Inwardly Rectifying
  • Protein Isoforms
  • Receptors, Drug
  • Sulfonylurea Receptors
  • Diazoxide
  • Phenobarbital