Drug Metabolism (DMPK) Assays

MicroConstants performs industry-standard assays, custom drug metabolism research, and IND-enabling studies to assess drug-drug interaction potential, metabolic stability, metabolite profiling, and protein binding. Whether you are in discovery, lead optimization, or collecting data for regulatory submissions, we will work with you to define the level of research appropriate for your study. Project results from drug metabolism studies can be presented as a formal report suitable for IND submissions, or as informal reports such as raw data tables in Excel format.


Metabolic Stability Assays

Metabolic stability assays are helpful when trying to determine the potential half-life of a compound when dosed to animals or humans. We determine the stability of a test article in a variety of enzyme sources, including: hepatocytes, liver microsomal preparations, hepatic cytosol, hepatic mitochrondrial fraction, hepatic S9 fraction, and membrane preparations from recombinant bacteria or eukaryotic cells. The time points are customized for each project, and the deliverables include raw data, percent remaining, and half-life values.

Metabolite Profiling

We are able to generate and compare metabolite profiles to assist with species selection for toxicology studies. These studies are performed using accurate mass spectrometry (QTof Premier) to analyze samples from metabolic stability assays or in-life dosing studies. We search the data sets for potential metabolites (using Metabolynx XS), and compare the time profiles of parent compound loss and metabolite formation using enzyme sources from various animal species. Metabolite profiling studies can also be specifically designed to look for unique or disproportionate human metabolites.

Presentation: Adventures in Metabolite Profiling with an Accurate Mass QTof (PDF)

Metabolite Identification / Metabolite ID

We identify metabolites in profiling studies, or characterize impurities in your API, using accurate mass spectrometry (QTof Premier) with collision cell optimization. Samples are generated either in vivo or in vitro. A metabolite standard may also be supplied for comparison of the retention time and product ion spectra with those of the postulated metabolite.

Drug-Drug Interaction Studies (CYP/UGT induction, inhibition & identification)

One of the concerns of developing new pharmaceutical candidates is how the compound will interact with co-administered medications. These drug-drug interactions result in different pharmacokinetic profiles and may lead to an adverse event or loss of efficacy for either the candidate or the marketed medicine. We offer a range of in vitro services to evaluate the potential for drug-drug interaction, including cytochrome P450 (CYP450) induction studies, CYP/UGT inhibition studies, and CYP/UGT reaction phenotyping. Read more.

Protein Binding Assays

Equilibrium dialysis, ultrafiltration, or ultracentrifugation are used to determine the extent of drug binding to plasma, or to proteins such as human serum albumin, or α1-acid glycoprotein. Multiple concentrations can be tested to obtain Kd estimates. We can also use in vivo samples to assess binding values. Read more.

Blood-to-Plasma Partition Ratio Determination

MicroConstants performs blood-to-plasma partition ratio studies to determine the blood-to-plasma ratio for test articles. Knowing the distribution of a drug candidate between red blood cells and plasma is useful for a number of reasons, including the explanation of variability in measured plasma concentrations due to hemolysis. Additionally, compounds that preferentially distribute into red blood cells may have over-predicted clearance values based on plasma concentrations. Therefore, determining the blood-to-plasma ratio is important for deciding whether plasma or whole blood would provide more physiologically relevant pharmacokinetic parameters. For these studies, chloroquine is used as a positive control.

Caco-2 Permeability Studies

The Caco-2 system is recognized as a predictive model which can help predict human intestinal absorption and oral bioavailability. We use 24-well plates with seeded and differentiated (21-days) Caco-2 cells to assess the apparent permeability of the test article across the intestinal barrier. By determining both the apical to basolateral (A-B) and the basolateral to apical (B A) permeability, the efflux ratio can be calculated. Additionally, inhibition of the P glycoprotein transporter can help determine if the test article is a P-gp substrate.

IND-enabling studies, industry standard & custom drug metabolism assays, including:

  • Metabolic stability assays to determine potential half-life
  • Metabolite profiling using accurate mass spectrometry
  • Metabolite identification and characterization
  • Protein binding assays to assess amounts of drug binding to plasma, proteins, etc.

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