A Cocktail Interaction Study Evaluating the Drug-Drug Interaction Potential of the Perpetrator Drug ASP8477 at Multiple Ascending Dose Levels.

ASP8477 (molecular weight 325.36 g/mol) is a fatty acid amide hydrolase inhibitor intended for the treatment of neuropathic pain. Results from in vitro studies indicated that ASP8477 is a direct inhibitor of cytochrome P450 (CYP) 2C8, 2C9, 2C19, 2D6, and 3A4 enzymes at expected efficacious concentrations, with the strongest effect on CYP2C19; a phase 1 study confirmed ASP8477 to be a CYP2C19 inhibitor. To further evaluate the interaction potential of ASP8477, a cocktail interaction study was performed using the probe substrates of the validated Inje cocktail containing losartan (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), and midazolam (CYP3A4). Because ASP8477 shows nonlinear pharmacokinetics, 3 doses (20, 60, and 100 mg) were evaluated. This study revealed changes in exposure (area under the concentration-time curve) of the probe substrates after treatment with 20, 60, and 100 mg ASP8477, respectively, compared with substrates alone with geometric mean ratios of: midazolam, 119%, 151%, and 158%; losartan, 107%, 144%, and 190%; omeprazole, 213%, 456%, and 610%; and dextromethorphan, 138%, 340%, and 555% (with increasing doses, respectively). Overall, ASP8477 was a weak inhibitor for CYP3A4 and CYP2C9, a moderate to strong inhibitor for CYP2C19, and a weak to strong inhibitor for CYP2D6, with doses from 20 to 100 mg. This study confirmed that the Inje cocktail approach was able to detect relevant drug-drug interactions impacting further development of ASP8477 and future therapeutic use. With the approach used here, the inhibiting effect of a perpetrator drug on different CYP enzymes can be evaluated, and at different doses, thereby supporting dose recommendations for potential interactions.

Physiologically Based Pharmacokinetic Model Qualification and Reporting Procedures for Regulatory Submissions: A Consortium Perspective.

This work provides a perspective on the qualification and verification of physiologically based pharmacokinetic (PBPK) platforms/models intended for regulatory submission based on the collective experience of the Simcyp Consortium members. Examples of regulatory submission of PBPK analyses across various intended applications are presented and discussed. European Medicines Agency (EMA) and US Food and Drug Administration (FDA) recent draft guidelines regarding PBPK analyses and reporting are encouraging, and to advance the use and acceptability of PBPK analyses, more clarity and flexibility are warranted.

An Exploratory Study in Healthy Male Subjects of the Mechanism of Mirabegron-Induced Cardiovascular Effects.

To explore the role of ß1 -adrenoceptors (ARs) in the heart rate response to the selective ß3 -adrenoceptor agonist mirabegron, 12 young male volunteers received single oral doses of the nonselective ß1/2 -AR antagonist propranolol (160 mg), the selective ß1 -AR antagonist bisoprolol (10 mg), or placebo on days 1 and 5 of each period in a 3-period crossover study. On day 5, dosing was followed by a supratherapeutic dose of mirabegron (200 mg). Vital signs, impedance cardiography, and plasma renin activity were collected. Mirabegron increased heart rate and systolic blood pressure and reduced stroke volume, whereas cardiac output and diastolic blood pressure were unaffected. Mirabegron-induced changes were attenuated by propranolol and bisoprolol. The data indicate that mirabegron has a positive chronotropic effect at supratherapeutic concentrations, which is at least partly mediated by stimulation of ß1 -AR.

Differential oxidation of deoxyribose in DNA by gamma and alpha-particle radiation.

Emerging evidence points to the importance of deoxyribose oxidation in the toxicity of oxidative DNA damage, including the formation of protein-DNA crosslinks and base adducts. With the goal of understanding the differences in deoxyribose oxidation chemistry known to occur with different oxidants, we have compared the formation of one product of 3'-oxidation of deoxyribose in DNA, 3'-phosphoglycolaldehyde (PGA) residues, in isolated DNA and cells exposed to ionizing radiations. A recently developed gas chromatography/negative chemical ionization mass spectrometry method was used to quantify PGA residues in purified DNA and in human TK6 lymphoblastoid cells exposed to gamma radiation (60Co) and alpha particles (241Am). The level of PGA residues was then correlated with the total quantity of deoxyribose oxidation determined by plasmid topoisomer analysis. Alpha-particle irradiation (0-100 Gy) of purified DNA in 50 mM potassium phosphate (pH 7.4) produced a linear dose response of 0.13 PGA residues per 10(6) nucleotides per gray. When normalized to an estimate of the total number of deoxyribose oxidation events (2.0 per 10(6) nucleotides per gray), PGA formation occurred in 7% (+/-0.5) of deoxyribose oxidation events produced by alpha-particle radiation. In contrast, the efficiency of PGA formation in gamma-irradiated DNA was found to be 1% (+/-0.02), which indicates a shift in the chemistry of deoxyribose oxidation, possibly as a result of the different track structures of the two types of ionizing radiation. Studies with gamma radiation were extended to TK6 cells, in which it was observed that gamma radiation produced a linear dose response of 0.0019 PGA residues per 10(6) nucleotides per gray. This is consistent with an approximately 1000-fold quenching effect in cells, similar to the results of other published studies of oxidative DNA damage in vivo.

Combination treatment with ipragliflozin and metformin: a randomized, double-blind, placebo-controlled study in patients with type 2 diabetes mellitus.

BACKGROUND: Ipragliflozin (ASP1941) is a selective sodium glucose cotransporter 2 inhibitor in clinical development for the treatment of patients with type 2 diabetes mellitus (T2DM). OBJECTIVES: The primary objective was to evaluate the safety profile and tolerability of ipragliflozin as a glucose-lowering agent in combination with stable metformin therapy in patients with T2DM. A secondary objective was to evaluate the effect of ipragliflozin on the pharmacokinetic (PK) properties of metformin. METHODS: Thirty-six patients with T2DM stable on metformin therapy (850, 1000, or 1500 mg bid) were randomized in a double-blind manner to receive ipragliflozin (300 mg qd; n = 18) or matching placebo (n = 18) for 14 days. Safety profiles, including monitoring of hypoglycemic events, treatment-emergent adverse events (TEAEs), laboratory measurements, and vital signs were assessed throughout the study. The PK properties of metformin and ipragliflozin were determined in plasma. The geometric mean ratio and its 90% CI for the maximum plasma concentration and AUC(0-10) were calculated for metformin + ipragliflozin (day 14) versus metformin alone (day -1). Pharmacodynamic properties were assessed by measurement of urinary glucose excretion over 24 hours (UGE(0-24)). RESULTS: All the TEAEs, except 1, were mild. Fifteen TEAEs were observed in the ipragliflozin group (7 of 18 patients [38.9%]), and 19 TEAEs were observed in the placebo group in (8 of 18 patients [44.4%]). Treatment-related TEAEs were reported by 3 of 18 patients (16.7%) receiving metformin + ipragliflozin and by 5 of 18 patients (27.8%) receiving metformin + placebo. No hypoglycemic events (blood glucose level <54 mg/L [to convert to millimoles per liter, multiply by 0.0555]) were observed. The geometric mean ratios for C(max) and AUC(0-10) of metformin + ipragliflozin versus metformin alone were 1.11 (90% CI, 1.03-1.19) and 1.18 (90% CI, 1.08-1.28), respectively. After ipragliflozin treatment, UGE(0-24) on day 14 (74.9 g) was significantly higher than that in the placebo group (3.6 g) and at baseline (3.3 g). CONCLUSIONS: Combination treatment for 14 days with ipragliflozin and metformin was well tolerated in patients withT2DM without hypoglycemia. The addition of ipragliflozin (300 mg qd) to metformin therapy did not result in a clinically relevant change in the PK properties of metformin. ClinicalTrials.gov identifier: NCT01302145.

Analysis of 3'-phosphoglycolaldehyde residues in oxidized DNA by gas chromatography/negative chemical ionization/mass spectrometry.

Deoxyribose oxidation in DNA represents a biologically important facet of oxidative DNA damage that gives rise to protein-DNA cross-links and base adducts. Toward the goal of quantifying deoxyribose oxidation chemistry in cells, we report a method for the quantification of 3'-phosphoglycolaldehyde (PGA) residues, which likely arise from 3'-oxidation of deoxyribose in DNA. The method exploits the aldehyde moiety in PGA by derivatization as a stable oxime with pentafluorobenzylhydroxylamine, followed by solvent extraction and gas chromatography/negative chemical ionization/mass spectrometry. A stable isotopically labeled [(13)C(2)]PGA was synthesized and used as an internal standard. The assay showed a linear response over the range of 30 fmol to 300 pmol, and its precision was verified by analysis of a synthetic, PGA-containing oligodeoxynucleotide. The limit of detection in the presence of DNA was 30 fmol per sample, corresponding to two molecules of PGA in 10(6) nucleotides for 170 microg of DNA. Samples were exposed to 0-100 Gy of (60)Co gamma-radiation, which resulted in a linear dose-response of 1.5 PGA residues per 10(6) nucleotides per Gy and a radiation chemical yield (G-value) of 0.0016 micromol/J. When compared to the total quantity of deoxyribose oxidation occurring under the same conditions (141 oxidation events per 10(6) nucleotides per Gy; determined by plasmid topoisomer analysis), PGA formation occurs in 1% of deoxyribose oxidation events. This small fraction is consistent with current models of limited solvent accessibility of the 3'-position of deoxyribose, although partitioning of 3'-chemistry could lead to other damage products that would increase the fraction of oxidation at this site in deoxyribose.