Radiometric Analysis

One of the oldest methods used for the quantitation of drug molecules is radiometric analysis. This generally involves quantitation of radiation from beta-emitting radioactive isotopes such as 14C, 3H or 32P. Radiometric analysis is one of the most precise, sensitive, and efficient detection methods; however, there are many technical and social challenges with using this … Continued

Ligand Binding Assays

Our discussions of various bioanalytical methodologies over the past few weeks has focused on chromatography and small molecule analysis. Today we are going to discuss a collection of methods that is commonly used for large molecules, such as peptides, peptides and macro-molecules. These molecules are often called “biologics” because they are generally derived from endogenous … Continued

Understanding LC/MS/MS

The most common bioanalytical method in use today is LC/MS/MS, or liquid chromatography (LC) tandem mass spectrometry (MS). This is a very versatile, robust, and sensitive methodology that is used for nearly all small molecules. In addition, this technology is amenable to automation and unattended analysis. The LC/MS/MS methodology is very similar to HPLC/UV, which … Continued

Application of a Physiologically-based Pharmacokinetic Model to Predict OATP1B1-related Variability in Pharmacodynamics of Rosuvastatin

Typically, pharmacokinetic-pharmacodynamic (PK/PD) models use plasma concentration as the input that drives the PD model. However, interindividual variability in uptake transporter activity can lead to variable drug concentrations in plasma without discernible impact on the effect site organ concentration. A physiologically based PK/PD model for rosuvastatin was developed that linked the predicted liver concentration to the PD response model. The model was then applied to predict the effect of genotype-dependent uptake … Continued

Simulation of Monoclonal Antibody Pharmacokinetics in Humans Using a Minimal Physiologically-based Model

Compared to small chemical molecules, antibodies and Fc-containing derivatives (mAbs) have unique pharmacokinetic behavior characterized by relatively poor cellular permeability, minimal renal filtration, binding to FcRn, target-mediated drug disposition, and disposition via lymph. A minimal physiologically based pharmacokinetic (PBPK) model to describe the pharmacokinetics of mAbs in humans was developed. Within the model, the body is divided into three physiological compartments; plasma, a single tissue compartment and lymph. The … Continued

What is HPLC/UV?

In my series about bioanalysis for the pharmacokineticist, I thought I would start with the bioanalysis methodology that was in use when I began my career in pharmaceutical development: HPLC/UV. The first part of this method (HPLC) is the separation technology. The second part (UV) is the detection technology. In the remainder of this post, … Continued

Bioanalysis from a PK Perspective

The field of bioanalytical chemistry, or bioanalysis, is an important area of research that has a direct impact on the work of pharmacokineticists. Essentially, bioanalysis converts a blood sample (or any other matrix) into a drug concentration by the use of analytical equipment. Over the next few weeks, I would like to cover a variety … Continued

Model of the Distribution of Diastolic Left Ventricular Posterior Wall Thickness in Healthy Adults and Its Impact on the Behavior of a String of Virtual Cardiomyocytes

Correlation of the thickness of the left ventricular posterior wall (LVPWd) with various parameters, including age, gender, weight and height, was investigated in this study using regression models. Multicenter derived database comprised over 4,000 healthy individuals. The developed models were further utilized in the in vitro–in vivo (IVIV) translation of the drug cardiac safety data … Continued

A Re-evaluation and Validation of Ontogeny Functions for CYPs 1A2 and 3A4 Based on In Vivo Data

Current cytochrome P450 (CYP) 1A2 and 3A4 ontogeny profiles, which are derived mainly from in vitro studies and incorporated in pediatric physiologically based pharmacokinetic models, have been reported to under-predict the in vivo clearances of some model substrates in neonates and infants. We report ontogeny functions for these enzymes as pediatric to adult relative intrinsic … Continued