Michael Gerisch

Substituted uracil derivatives as potent inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1).

A new class of PARP-1 inhibitors, namely substituted fused uracil derivatives were synthesised. Starting from a derivative with an IC(50)=2microM the chemical optimisation program led to compounds with more than a 100-fold increase in potency (IC(50)<20nM). Additionally, physicochemical and pharmacokinetic properties were evaluated. It could be shown that compounds bearing a piperazine or phenyl substituted betaAla-Gly side chain exhibited the best overall profile.

Mass balance, metabolic disposition, and pharmacokinetics of a single oral dose of regorafenib in healthy human subjects

PurposeTo evaluate the mass balance, metabolic disposition, and pharmacokinetics of a single dose of regorafenib in healthy volunteers. In addition, in vitro metabolism of regorafenib in human hepatocytes was investigated.MethodsFour healthy male subjects received one 120xa0mg oral dose of regorafenib containing approximately 100xa0µCi (3.7xa0MBq) [14C]regorafenib. Plasma concentrations of parent drug were derived from HPLC–MS/MS analysis and total radioactivity from liquid scintillation counting (LSC). Radiocarbon analyses used HPLC with fraction collection followed by LSC for all urine samples, plasma, and fecal homogenate extracts. For the in vitro study, [14C]regorafenib was incubated with human hepatocytes and analyzed using HPLC–LSC and HPLC–HRMS/MS.ResultsRegorafenib was the major component in plasma, while metabolite M-2 (pyridine N-oxide) was the most prominent metabolite. Metabolites M-5 (demethylated pyridine N-oxide) and M-7 (N-glucuronide) were identified as minor plasma components. The mean concentration of total radioactivity in plasma/whole blood appeared to plateau at 1–4xa0h and again at 6–24xa0h post-dose. In total, 90.5% of administered radioactivity was recovered in the excreta within a collection interval of 12 days, most of which (71.2%) was eliminated in feces, while excretion via urine accounted for 19.3%. Regorafenib (47.2%) was the most prominent component in feces and was not excreted into urine. Excreted metabolites resulted from oxidative metabolism and glucuronidation.ConclusionsRegorafenib was eliminated predominantly in feces as well as by hepatic biotransformation. The multiple biotransformation pathways of regorafenib decrease the risk of pharmacokinetic drug–drug interactions.

Pharmacokinetics of the Novel, Selective, Non-steroidal Mineralocorticoid Receptor Antagonist Finerenone in Healthy Volunteers: Results from an Absolute Bioavailability Study and Drug–Drug Interaction Studies In Vitro and In Vivo

Background and ObjectivesFinerenone is a selective, non-steroidal mineralocorticoid receptor antagonist. In vivo and in vitro studies were performed to assess absolute bioavailability of finerenone, the effect of metabolic enzyme inhibitors on the pharmacokinetics of finerenone and its metabolites, the quantitative contribution of the involved enzymes cytochrome P450 (CYP)xa03A4 and CYP2C8 and the relevance of gut wall versus liver metabolism.MethodsThe pharmacokinetics, safety and tolerability of finerenone (1.25–10xa0mg orally or 0.25–1.0xa0mg intravenously) were evaluated in healthy male volunteers in four crossover studies. Absolute bioavailability was assessed in volunteers receiving finerenone orally and by intravenous infusion (nu2009=u200915) and the effects of erythromycin (nu2009=u200915), verapamil (nu2009=u200913) and gemfibrozil (nu2009=u200916) on finerenone pharmacokinetics were investigated. Finerenone was also incubated with cryopreserved human hepatocytes in vitro in the presence of erythromycin, verapamil or gemfibrozil.ResultsFinerenone absolute bioavailability was 43.5% due to first-pass metabolism in the gut wall and liver. The geometric mean AUC0–∞ ratios of finerenone (drugu2009+u2009inhibitor/drug alone) were 3.48, 2.70 and 1.10 with erythromycin, verapamil and gemfibrozil, respectively. The contribution ratio of CYP3A4 to the metabolic clearance of finerenone derived from these values was 0.88–0.89 and was consistent with estimations based on in vitro data, with the remaining metabolic clearance due to CYP2C8 involvement.ConclusionFinerenone is predominantly metabolized by CYP3A4 in the gut wall and liver. Increases in systemic exposure upon concomitant administration of inhibitors of this isoenzyme are predictable and consistent with in vitro data. Inhibition of CYP2C8, the second involved metabolic enzyme, has no relevant effect on finerenone in vivo.

Biotransformation of Finerenone, a Novel Nonsteroidal Mineralocorticoid Receptor Antagonist, in Dogs, Rats, and Humans, In Vivo and In Vitro

Mass balance and biotransformation of finerenone, a nonsteroidal mineralocorticoid receptor antagonist, were investigated in four healthy male volunteers following a single oral administration of 10 mg (78 μCi) of [14C]finerenone and compared with data from studies in dogs and rats. The total recovery of the administered radioactivity was 101% in humans, 94.7% in dogs, and 95.2% in rats. In humans, radioactivity was mainly excreted renally (80%); in rats, it was primarily the biliary/fecal route (76%); and in dogs, excretion was more balanced. Finerenone was extensively metabolized in all species by oxidative biotransformation, with minor amounts of unchanged drug in excreta (humans: 1%; dogs, rats: <9%). In vitro studies suggested cytochrome P450 3A4 was the predominant enzyme involved in finerenone metabolism in humans. Primary metabolic transformation involved aromatization of the dihydronaphthyridine moiety of metabolite M1 as a major clearance pathway with a second oxidative pathway leading to M4. These were both prone to further oxidative biotransformation reactions. Naphthyridine metabolites (M1–M3) were the dominant metabolites identified in human plasma, with no on-target pharmacological activity. In dog plasma, finerenone and metabolite M2 constituted the major components; finerenone accounted almost exclusively for drug-related material in rat plasma. For metabolites M1–M3, axial chirality was observed, represented by two atropisomers (e.g., M1a and M1b). Analysis of plasma and excreta showed one atropisomer (a-series, >79%) of each metabolite predominated in all three species. In summary, the present study demonstrates that finerenone is cleared by oxidative biotransformation, mainly via naphthyridine derivatives.

Pharmacokinetics of intravenous pan-class I phosphatidylinositol 3-kinase (PI3K) inhibitor [14C]copanlisib (BAY 80-6946) in a mass balance study in healthy male volunteers

PurposeTo determine the pharmacokinetics of radiolabeled copanlisib (BAY 80-6946) in healthy male volunteers and to investigate the disposition and biotransformation of copanlisib.MethodsA single dose of 12xa0mg copanlisib containing 2.76xa0MBq [14C]copanlisib was administered as a 1-h intravenous infusion to 6 volunteers with subsequent sampling up to 34xa0days. Blood, plasma, urine and feces were collected to monitor total radioactivity, parent compound and metabolites.ResultsCopanlisib treatment was well tolerated. Copanlisib was rapidly distributed throughout the body with a volume distribution of 1870xa0L and an elimination half-life of 52.1-h (range 40.4–67.5-h). Copanlisib was the predominant component in human plasma (84% of total radioactivity AUC) and the morpholinone metabolite M1 was the only circulating metabolite (about 5%). Excretion of drug-derived radioactivity based on all 6 subjects was 86% of the dose within a collection interval of 20–34xa0days with 64% excreted into feces as major route of elimination and 22% into urine. Unchanged copanlisib was the main component excreted into urine (15% of dose) and feces (30% of dose). Excreted metabolites (41% of dose) of copanlisib resulted from oxidative biotransformation.ConclusionsCopanlisib was eliminated predominantly in the feces compared to urine as well as by hepatic biotransformation, suggesting that the clearance of copanlisib would more likely be affected by hepatic impairment than by renal dysfunction. The dual mode of elimination via unchanged excretion of copanlisib and oxidative metabolism decreases the risk of clinically relevant PK-related drug–drug interactions.