Peter Stopfer

Dr. Peter Stopfer

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Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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23 April 2019 in Clinical Pharmacokinetics
Verified
Journal Article
Open access
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SWSven Wind
Sven Wind
USUlrike Schmid
Ulrike Schmid
MFMatthias Freiwald
Matthias Freiwald
KMKristell Marzin
Kristell Marzin
RLRalf Lotz
Ralf Lotz
CDClaudia Dallinger
Claudia Dallinger
Nintedanib is an oral, small-molecule tyrosine kinase inhibitor approved for the treatment of idiopathic pulmonary fibrosis and patients with advanced non-small cell cancer of adenocarcinoma tumour histology. Nintedanib competitively binds to the kinase domains of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF). Studies in healthy volunteers and in patients with advanced cancer have shown that nintedanib has time-independent pharmacokinetic characteristics. Maximum plasma concentrations of nintedanib are reached approximately 2–4 h after oral administration and thereafter decline at least bi-exponentially. Over the investigated dose range of 50–450 mg once daily and 150–300 mg twice daily, nintedanib exposure increases are dose proportional. Nintedanib is metabolised via hydrolytic ester cleavage, resulting in the formation of the free acid moiety that is subsequently glucuronidated and excreted in the faeces. Less than 1% of drug-related radioactivity is eliminated in urine. The terminal elimination half-life of nintedanib is about 10–15 h. Accumulation after repeated twice-daily dosing is negligible. Sex and renal function have no influence on nintedanib pharmacokinetics, while effects of ethnicity, low body weight, older age and smoking are within the inter-patient variability range of nintedanib exposure and no dose adjustments are required. Administration of nintedanib in patients with moderate or severe hepatic impairment is not recommended, and patients with mild hepatic impairment should be monitored closely and the dose adjusted accordingly. Nintedanib has a low potential for drug–drug interactions, especially with drugs metabolised by cytochrome P450 enzymes. Concomitant treatment with potent inhibitors or inducers of the P-glycoprotein transporter can affect the pharmacokinetics of nintedanib. At an investigated dose of 200 mg twice daily, nintedanib does not have proarrhythmic potential.

27 December 2011 in Cancer Chemotherapy and Pharmacology
Verified
Journal Article
Closed access
PSPeter Stopfer
Peter Stopfer
KMKristell Marzin
Kristell Marzin
HNHans Narjes
Hans Narjes
DGDietmar Gansser
Dietmar Gansser
MSMehdi Shahidi
Mehdi Shahidi
TEThomas Ebner
Thomas Ebner

30 November 2010 in Xenobiotica
Verified
Journal Article
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PSPeter Stopfer
Peter Stopfer
KRKarin Rathgen
Karin Rathgen
DBDaniel Bischoff
Daniel Bischoff
SLSilke Lüdtke
Silke Lüdtke
KMKristell Marzin
Kristell Marzin
TEThomas Ebner
Thomas Ebner
The pharmacokinetics and metabolism of BIBF 1120, an oral triple angiokinase inhibitor targeting vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and fibroblast growth factor receptor (FGFR), were studied in healthy male volunteers (n = 8) who had received a single oral dose of 100 mg [14C]-radiolabelled BIBF 1120 administered as solution. BIBF 1120 was well-tolerated and rapidly absorbed; median time to reach maximum plasma concentrations was 1.3 h and gMean terminal half-life was 13.7 h. A relatively high apparent total body clearance and volume of distribution possibly indicated a high tissue distribution. Plasma concentrations of BIBF 1120 plus carboxylate metabolite BIBF 1202 were lower than the total [14C]-radioactivity in plasma, indicating presence of additional metabolites. Total recovery in excreta was 94.7% 1 week post-dose; mass balance was considered complete after 96 h. BIBF 1120 and metabolites were mainly excreted via faeces. The major metabolic pathway for BIBF 1120 was methyl ester cleavage to BIBF 1202. Subsequently, the free carboxyl group of BIBF 1202 was glucuronidated to 1-O-acylglucuronide. Pathways of minor importance were oxidative N-demethylation to yield BIBF 1053, and oxidation of the piperazine moiety and conjugation. Glucuronidation of the parent drug and formylation of the secondary aliphatic amine of the piperazine ring played a minor role.

3 June 2016 in Clinical Pharmacology & Therapeutics
Verified
Journal Article
Open access
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PSPeter Stopfer
Peter Stopfer
TGT Giessmann
T Giessmann
KHK Hohl
K Hohl
ASA Sharma
A Sharma
NIN Ishiguro
N Ishiguro
FMF Müller
F Müller
This article reports the clinical investigation of a probe drug cocktail containing substrates of key drug transporters. Single oral doses of 0.25 mg digoxin (P‐gp), 5 mg furosemide (OAT1 and OAT3), 500 mg metformin (OCT2, MATE1, and MATE2‐K), and 10 mg rosuvastatin (OATP1B1, OATP1B3, and BCRP) were administered separately or as a cocktail in a randomized six‐period crossover trial in 24 healthy male volunteers. As a cocktail, relative bioavailabilities of digoxin and metformin and furosemide AUC0‐tz were similar to separate dosing. However, when administered as a cocktail the Cmax of furosemide was 19.1% lower and the Cmax and AUC0‐tz of rosuvastatin were 38.6% and 43.4% higher, respectively. In addition, the effects of increased doses of metformin or furosemide on the cocktail were investigated in 11 and 12 subjects, respectively. The cocktail explored in this trial has the potential to be used for the in vivo screening of transporter‐mediated drug–drug interactions. © 2016 American Society for Clinical Pharmacology and Therapeutics

5 June 2020 in Clinical Pharmacokinetics
Verified
Journal Article
Open access
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SWSabrina T. Wiebe
Sabrina T. Wiebe
TGThomas Giessmann
Thomas Giessmann
KHKathrin Hohl
Kathrin Hohl
SSSven Schmidt-Gerets
Sven Schmidt-Gerets
EHEdith Hauel
Edith Hauel
PSPeter Stopfer
Peter Stopfer
Background and Objective A novel cocktail containing four substrates of key drug transporters was previously optimized to eliminate mutual drug–drug interactions between the probes digoxin (P-glycoprotein substrate), furosemide (organic anion transporter 1/3), metformin (organic cation transporter 2, multidrug and toxin extrusion protein 1/2-K), and rosuvastatin (organic anion transporting polypeptide 1B1/3, breast cancer resistance protein). This clinical trial investigated the effects of four commonly employed drug transporter inhibitors on cocktail drug pharmacokinetics. Methods In a randomized open-label crossover trial in 45 healthy male subjects, treatment groups received the cocktail with or without single oral doses of rifampin, verapamil, cimetidine or probenecid. Concentrations of the probe drugs in serial plasma samples and urine fractions were measured by validated liquid chromatography-tandem mass spectrometry assays to assess systemic exposure. Results The results were generally in accordance with known in vitro and/or clinical drug–drug interaction data. Single-dose rifampin increased rosuvastatin area under the plasma concentration–time curve up to the last quantifiable concentration (AUC0–tz) by 248% and maximum plasma concentration (Cmax) by 1025%. Probenecid increased furosemide AUC0–tz by 172% and Cmax by 23%. Cimetidine reduced metformin renal clearance by 26%. The effect of single-dose verapamil on digoxin systemic exposure was less than expected from multiple-dose studies (AUC0–tz unaltered, Cmax + 22%). Conclusions Taking all the interaction results together, the transporter cocktail is considered to be validated as a sensitive and specific tool for evaluating transporter-mediated drug–drug interactions in drug development. Clinical Trial Registration EudraCT number 2017-001549-29.

17 April 2018 in British Journal of Clinical Pharmacology
Verified
Journal Article
Open access
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PSPeter Stopfer
Peter Stopfer
TGThomas Giessmann
Thomas Giessmann
KHKathrin Hohl
Kathrin Hohl
SHSabine Hutzel
Sabine Hutzel
SSSven Schmidt
Sven Schmidt
FMFabian Müller
Fabian Müller
Aims: Previous pharmacokinetic characterization of a transporter probe cocktail containing digoxin (P‐gp), furosemide (OAT1, OAT3), metformin (OCT2, MATE1, MATE2‐K) and rosuvastatin (OATP1B1, OATP1B3, BCRP) in healthy subjects showed increases in rosuvastatin systemic exposure compared to rosuvastatin alone. In this trial, the doses of metformin and furosemide as putative perpetrators were reduced to eliminate their drug–drug interaction (DDI) with rosuvastatin.Methods: In a randomized, open‐label, single‐centre, five‐treatment, five‐period crossover trial, 30 healthy male subjects received as reference treatments separately 0.25 mg digoxin, 1 mg furosemide, 10 mg metformin and 10 mg rosuvastatin, and as test treatment all four drugs administered together as a cocktail. Primary pharmacokinetic endpoints were AUC0‐tz (area under the plasma concentration–time curve from time zero to the last quantifiable concentration) and Cmax (maximum plasma concentration) of each probe drug.Results: Geometric mean ratios and 90% confidence intervals of test (cocktail) to reference (single drug) for AUC0‐tz were 96.4% (88.2–105.3%) for digoxin, 102.6% (93.8–112.3%) for furosemide, 97.5% (93.5–101.6%) for metformin and 105.0% (96.4–114.4%) for rosuvastatin, indicating lack of interaction. The same analysis for Cmax and for pharmacokinetic parameters of urinary excretion of all cocktail components also indicated no DDI.Conclusions: Digoxin (0.25 mg), furosemide (1 mg), metformin (10 mg) and rosuvastatin (10 mg) exhibit no mutual pharmacokinetic interactions and are well tolerated administered as a cocktail. The cocktail is thus optimized and has the potential to be used as a screening tool for clinical investigation of transporter‐mediated DDI.