In vivo metabolic investigation of moxifloxacin using liquid chromatography/electrospray ionization tandem mass spectrometry in combination with online hydrogen/deuterium exchange experiments.
BACKGROUND
Tuberculosis is a leading cause of death from an infectious disease and moxifloxacin is an effective drug as compared to other fluoroquinolones. To date only two metabolites of the drug are known. Therefore, the present study on characterization of hitherto unknown in vivo metabolites of moxifloxacin using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) is undertaken.


METHODS
In vivo metabolites of moxifloxacin have been identified and characterized by using LC/ESI-MS/MS in combination with an online hydrogen/deuterium (H/D) exchange technique. To identify in vivo metabolites, blood, urine and faeces samples were collected after oral administration of moxifloxacin to Sprague-Dawley rats. The samples were prepared using an optimized sample preparation approach involving protein precipitation, liquid-liquid extraction followed by solid-phase extraction and LC/MS/MS analysis.


RESULTS
A total of nine phase I and ten phase II metabolites of moxifloxacin have been identified in urine samples including N-sulphated, glucuronide and hydroxylated metabolites which are also observed in plasma samples. In faeces samples, only the N-sulphated metabolite is observed. The structures of metabolites have been elucidated based on fragmentation patterns, accurate mass measurements and online H/D exchange LC/MS/MS experiments. Online H/D exchange experiments are used to support the identification and structural characterization of drug metabolites.


CONCLUSIONS
A total of 19 in vivo metabolites of moxifloxacin have been characterized using LC/ESI-MS/MS in combination with accurate mass measurements and online H/D exchange experiments. The main phase I metabolites of moxifloxacin are hydroxylated, decarbonylated, desmethylated and desmethylhydroxylated metabolites which undergo subsequent phase II glucuronidation pathways.
National Centre for Mass Spectrometry, Indian Institute of Chemical Technology, Hyderabad, 500 007, India.
B
B
Raju
M
M
Ramesh
Roshan M
RM
Borkar
R
R
Srinivas
Raju
R
Padiya
Sanjay K
SK
Banerjee
D000284:Administration, Oral; D000818:Animals; D001372:Aza Compounds / Q000097:blood / Q000737:chemistry / Q000378:metabolism* / Q000652:urine; D011232:Chemical Precipitation; D002853:Chromatography, Liquid / Q000379:methods*; D041961:Deuterium Exchange Measurement / Q000379:methods*; D005243:Feces / Q000737:chemistry; D024841:Fluoroquinolones; D007477:Ions / Q000737:chemistry; D059625:Liquid-Liquid Extraction; D008297:Male; D000077266:Moxifloxacin; D011804:Quinolines / Q000097:blood / Q000737:chemistry / Q000378:metabolism* / Q000652:urine; D051381:Rats; D017207:Rats, Sprague-Dawley; D052616:Solid Phase Extraction; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry
D001372:Aza Compounds; D024841:Fluoroquinolones; D007477:Ions; D011804:Quinolines; D000077266:Moxifloxacin