Investigation of Human in vivo Metabolism of SEP-227900 Using the Samples from First-in-Human Study by LC-HRMS/UV and NMR.

OBJECTIVE: The study aims to explore the human in vivo metabolism of SEP-227900 (4H-furo[3, 2-b] pyrrole-carboxylic acid, m.w 151.03), a D-amino-acid oxidase (DAAO) inhibitor, by using plasma and urine samples from first-in-human study. METHODS: The human plasma and urine samples were from a single dose cohort that consisted of 9 healthy male volunteers each received an 80- mg dose of SEP-227900 orally. The pooled pre-dose urine and the pooled 0-24 h urine sample were created across 9 subjects by equal volume. Plasma samples were pooled by equal volume across 9 subjects to obtain 0-12 h plasma for metabolite searching, and also pooled by timepoints across 9 subjects to obtain 0.5, 5, and 12-h plasma for semi-quantitation. The plasma was de-proteinized by acetonitrile (1:3 v/v plasma-acetonitrile), then the supernatant was dried down, reconstituted, and injected for LC-HRMS/UV analysis. The urine sample was just simply centrifuged before analysis. LC-HRMS/UV was utilized to search predictable and unknown metabolites and estimate their relative abundances. Accurate mass measurement by Orbitrap-MS and MS/MS was used for metabolite identification. Chromatographic separation was achieved on a MACMOD AQ C8 column (250 × 4.6 mm, 5-µm) with a gradient mobile phase (A: 10 mM NH4Ac; B: acetonitrile; flowrate: 0.700 ml/min) for a total run-time of 65 min. The definite position in the molecule for the glucuronidation metabolism was characterized by the detected migration phenomenon, methylation with diazomethane (CH2N2), and NMR. RESULTS: Unchanged parent drug and four metabolite peaks were detected in humans: M1 was a mono-oxidative metabolite of SEP-227900; M2 was a glucuronide conjugate of SEP-227900; M3 was a glycine conjugate of SEP-227900; M4 was a glycine conjugate of M1. The specific position of the oxidation in M1 solely based on the mass spectral (MS and MS/MS) data was not identified. However, for the major metabolite M2, the acyl glucuronidation was unambiguously determined through multiple pieces of experimental evidence such as the observation of a migration pattern, mono-methylation by diazomethane, and NMR measurement. This determination is of significance related to the safety evaluation of investigational new drug development. The glycine conjugate of SEP-227900, i.e., M3, was found to be the most abundant metabolite in human urine (approximately 3-fold higher level than the glucuronide level). All together (mainly glycine-conjugate and glucuronide), it resulted in greater than 80% of the dosed amount in urine excretion (a separate measurement showed 23% of the dosed amount in urine excretion as the glucuronide). CONCLUSION: Four metabolites were found in humans: SEP-227900-glycine conjugate, SEP- 227900-glucuronide, mono-oxidative metabolite, and its consequent glycine conjugate. The glucuronide metabolite was identified as acyl glucuronide. Greater than 80% of the dosed amount of SEP-227900 was excreted in the urine, mainly in the forms of glycine- and glucuronide- conjugates.

A sensitive liquid chromatography-tandem mass spectrometry method for quantitative determination of dasotraline in human plasma and its clinical application.

This manuscript describes a highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of dasotraline in human plasma. Dasotraline and the internal standard (IS) d4-13C4-dasotraline were extracted from the 0.500-mL plasma pre-mixed with 0.20-mL of 0.5 M sodium bicarbonate solution by a 3-mL of hexane containing 0.7 % sec-butyl alcohol. The organic extract, after dried down, was reconstituted in 150 µL acetonitrile containing 0.1 % formic acid. Forty (40) µL of the resulted sample was injected into LC-MS/MS for analysis. Chromatographic separation was on a Betasil Silica column. MS/MS detection was by monitoring m/z 275→159 and 283→160 for dasotraline and IS, respectively. Peak area ratio of analyte/IS was used for constructing calibration curve and calculating sample concentration. The retention time was ∼3.1 min for both dasotraline and IS. The validated linear range was 5-5000 pg/mL with correlation coefficient r ≥ 0.999. Intra-run precision and accuracy were ≤ 7.3 % CV (n = 6) and 94.4-101.0 % of nominals. Inter-run precision and accuracy were ≤ 4.7 % CV (n = 18) and 96.1-99.8 % of nominals. Plasma sample was confirmed stable for 8 cycles of freeze/thaw, 29 h on bench-top, and up to 977 days of storage at both -20 °C and -70 °C. This method was successfully applied to analyze pharmacokinetic (PK) samples from a single ascending dose (SAD) clinical study with healthy subjects. PK results indicated that dasotraline was slowly absorbed (tmax: 10-12 h) and slowly eliminated (terminal elimination half-life, i.e. t1/2: 47-77 h) with dose proportional Cmax but slightly greater than dose proportional AUC with increase of dosed amount.

Absorption, distribution, metabolism, and excretion of [14C]-dasotraline in humans.

Dasotraline is a dopamine and norepinephrine reuptake inhibitor, and the early clinical trials show a slow absorption and long elimination half-life. To investigate the absorption, distribution, metabolism, and excretion of dasotraline in humans, a single dose of [14C]-dasotraline was administered to eight healthy male adult volunteers. At 35 days, 90.7% of the dosed radioactivity was recovered in the urine (68.3%) and feces (22.4%). The major metabolic pathways involved were: (1) amine oxidation to form oxime M41 and sequential sulfation to form M42 or glucuronidation to form M43; (2) N-hydroxylation and sequential glucuronidation to form M35; (3) oxidative deamination to form (S)-tetralone; (4) mono-oxidation of (S)-tetralone and sequential glucuronidation to form M31A and M32; and (5) N-acetylation to form (1R,4S)-acetamide M102. A total of 8 metabolites were detected and structurally elucidated with 4 in plasma (M41, M42, M43, and M35), 7 in urine (M41, M42, M43, M31A, M32, M35, and (S)-tetralone), and 3 in feces (M41, (S)-tetralone, and (1R,4S)-acetamide). The 2 most abundant circulating metabolites were sulfate (M42) and glucuronide (M43) conjugates of the oxime of dasotraline, accounting for 60.1% and 15.0% of the total plasma radioactivity, respectively; unchanged dasotraline accounted for 8.59%. The oxime M41 accounted for only 0.62% of the total plasma radioactivity and was detected only at early time points. M35 was a minor glucuronide metabolite, undetectable by radioactivity but identified by mass spectrometry. The results demonstrate that dasotraline was slowly absorbed, and extensively metabolized by oxidation and subsequent phase II conjugations. The findings from this study also demonstrated that metabolism of dasotraline by humans did not produce metabolites that may cause a safety concern.

Pharmacokinetics and Exposure-Response Relationships of Dasotraline in the Treatment of Attention-Deficit/Hyperactivity Disorder in Adults.

BACKGROUND AND OBJECTIVES: Dasotraline is a novel inhibitor of dopamine and norepinephrine reuptake currently being investigated in clinical studies for the treatment of attention-deficit/hyperactivity disorder (ADHD). Uniquely, relative to current ADHD medications, dasotraline has a slow absorption and long elimination half-life. Here we relate the pharmacokinetics and pharmacodynamics of dasotraline to reduction in ADHD symptoms based on simulated clinical trial outcomes. METHODS: Dasotraline pharmacokinetics were analyzed by population pharmacokinetic methodologies using data collected from 395 subjects after single or multiple oral dose administrations ranging from 0.2 to 36 mg (three phase I studies and one phase II ADHD study). Population pharmacokinetic and pharmacodynamic models related individual dasotraline exposures to norepinephrine metabolite 3,4-dihydroxyphenylglycol (DHPG) concentrations, ADHD symptoms, and study discontinuation (probability of dropout). RESULTS: Dasotraline pharmacokinetics were described by a one-compartment model with dual (linear plus nonlinear) elimination. In an ADHD population treated with dasotraline 4 or 8 mg/day, dasotraline was characterized by a mean apparent half-life of 47 h and plasma concentrations reached steady-state by 10 days of dosing. A population pharmacokinetic and pharmacodynamic model of DHPG indicated clinically significant norepinephrine transporter inhibition was achieved as a function of time-matched dasotraline concentrations. Dasotraline exposure reduced ADHD symptoms in a sigmoid E max time-course model. Clinical trial simulations described the effects of dose, duration, and sample size on clinical outcomes. CONCLUSION: These results related dasotraline pharmacokinetics to pharmacological activity in ADHD, and support the novel concept that maintaining constant, steady-state dopamine and norepinephrine reuptake inhibition throughout a 24-h dosing interval is a novel pharmacological approach to the management of ADHD symptoms. Clinicaltrials.gov identifier: NCT01692782.