Identification of Novel Metabolic Pathways of Sitagliptin (STG) by LC/MS and LC/MS2 after Incubations with Rat Hepatocytes

Abstract

Sitagliptin (STG), a drug for treating Type Ii Diabetes Mellitus (T2DM), has been associated with severe joint pain in some patients. In this paper the metabolic profile of the drug has been investigated in order to determine metabolism and formation of reactive compounds which may contribute to this adverse effect. Metabolism of STG was investigated in vitro by incubation with freshly isolated Sprague-Dawley rat hepatocytes, to characterize Phase I and II metabolites, and the reaction mixture analysed on a zwitter ionic hydrophilic interaction (ZIC ® -HILIC) column using LC-MS and LC-MS 2 utilising electrospray ionization (ESI) in the positive ion mode.STG was metabolised to yield eleven metabolites, but in total only 3.1% of the parent drug was metabolised over 2 hrs incubation. These metabolites were structurally characterized on the basis of accurate mass analyses and the major metabolic routes for STG determined to be via aromatic oxidation (0.86%) and desaturation of N-C and C-C of the piperazine (0.44%).Novel metabolites of STG detected using these methods included STG N-glucuronide (M6) and a di-ketone metabolite (M4), hydroxylation of both the amine group and aromatic ring followed by formation of glucuronide metabolites (M5, M5'), oxidative desaturation of NH 2 and di-hydroxylation of metabolites followed by loss of HF.Also, observed was an N-sulfate metabolite (0.07%) and acetylation followed by glucuronide conjugation was also found in trace amounts (<0.01%). MS 2 fragment ions provide additional structural confirmation providing a possible structure for most metabolites such as by fragment ion loss of the glucuronide group (176 Da) from metabolite M5 and loss of the phenolic sulfate (80 Da) of N-Sulfate metabolite (M7).Reduction reaction of piperazine ring probably generates highly electrophilic metabolite of STG, which may be susceptible to produce adverse effects. Furthermore, N-oxidation reaction forming reactive intermediates metabolic to give a hydroxylamine metabolite that may undergo further reactions to yield electrophilic intermediate metabolites.

Ozonation of Sitagliptin: Removal Kinetics and Elucidation of Oxidative Transformation Products

“…17 On the German market, the antidiabetic STG was launched in 2007 and is either applied in combination with metformin (preparation Janumet and Velmetia) or as an individual pharmaceutical (e.g., Januvia and Xelevia). 17,18 Since 2007, STG-containing products were increasingly administered (Figure S1). 18 Its human metabolic rate is very low; about 80% of the administered antidiabetic is excreted unchanged via urine 17,19 and thus, an elevated portion of administered STG enters WWTPs.…”

“…17,18 Since 2007, STG-containing products were increasingly administered (Figure S1). 18 Its human metabolic rate is very low; about 80% of the administered antidiabetic is excreted unchanged via urine 17,19 and thus, an elevated portion of administered STG enters WWTPs. Due to its elevated persistence and increasing consumption, it is discharged in significant quantities by WWTPs with concentrations up to 1.0 μg/L in WWTP effluents.…”

“…To the best of the author’s knowledge, there is no mechanistic study on the ozonation of environmentally relevant micropollutants containing an aliphatic primary amine as the main molecule site of reaction with ozone. Sitagliptin (STG) is a dipeptidyl peptidase-4 (DDP-4) inhibitor, which is administered for the treatment of diabetes mellitus type 2 . On the German market, the antidiabetic STG was launched in 2007 and is either applied in combination with metformin (preparation Janumet and Velmetia) or as an individual pharmaceutical (e.g., Januvia and Xelevia). , Since 2007, STG-containing products were increasingly administered (Figure S1).…”

“…Sitagliptin (STG) is a dipeptidyl peptidase-4 (DDP-4) inhibitor, which is administered for the treatment of diabetes mellitus type 2 . On the German market, the antidiabetic STG was launched in 2007 and is either applied in combination with metformin (preparation Janumet and Velmetia) or as an individual pharmaceutical (e.g., Januvia and Xelevia). , Since 2007, STG-containing products were increasingly administered (Figure S1). Its human metabolic rate is very low; about 80% of the administered antidiabetic is excreted unchanged via urine , and thus, an elevated portion of administered STG enters WWTPs.…”

“…On the German market, the antidiabetic STG was launched in 2007 and is either applied in combination with metformin (preparation Janumet and Velmetia) or as an individual pharmaceutical (e.g., Januvia and Xelevia). , Since 2007, STG-containing products were increasingly administered (Figure S1). Its human metabolic rate is very low; about 80% of the administered antidiabetic is excreted unchanged via urine , and thus, an elevated portion of administered STG enters WWTPs. Due to its elevated persistence and increasing consumption, it is discharged in significant quantities by WWTPs with concentrations up to 1.0 μg/L in WWTP effluents. − To the best of our knowledge, Henning et al performed the first study on the degradability of STG during biological wastewater treatment.…”