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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

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

What Can We Learn from Dose Normalization?

Dose normalization is a common calculation performed with pharmacokinetic parameters. The general process is to divide the PK parameters by the administered dose. This is performed for each individual or treatment group in a study, and then comparisons of dose-normalized parameters can be performed. But, why would we want to dose normalize PK parameters? What … Continued

Creating Templates in Phoenix WinNonlin

One of the most useful features of the new Phoenix WinNonlin software is the ability to re-use objects for new projects. In particular, it takes quite a bit of time to adjust all of the settings for figures in Phoenix. You need to adjust the font on both axes, change the legend labels, choose the … Continued

Extrapolating AUC to Infinity

Area under the curve or AUC is a pharmacokinetic statistic used to describe the total exposure to a drug. More specifically, it is the time-averaged concentration of drug circulating in the body fluid analyzed (normally plasma, blood or serum). Standard calculation of AUC involves using non-compartmental techniques to calculate the AUC from time 0 to … Continued

Simplifying Deconvolution

Deconvolution is used to evaluate the absorption kinetics of a drug. Unfortunately the term can be confusing and explanations are generally even more confusing. While deconvolution is not a simple topic, I believe it can be understood so that more scientists can apply the principles to their work. Before I define deconvolution, let me define … Continued

Cassette Dosing: Advantages and Challenges

Cassette dosing is a technique primarily used in drug discovery efforts in non-clinical studies to collect pharmacokinetic data from multiple drug candidates in a single experiment. A typical cassette dosing pharmacokinetic study involves simultaneous administration of 5-10 compounds to a set of animals. Serial blood samples are obtained and LC/MS/MS techniques are used to measure … Continued

What is GLP (Good Laboratory Practice)?

Good laboratory practice or GLP is a set of principles intended to assure the quality and integrity of non-clinical laboratory studies that are intended to support research or marketing permits for products regulated by government agencies. The term GLP is most commonly associated with the pharmaceutical industry and the required non-clinical animal testing that must … Continued

Understanding Steady State Pharmacokinetics

“Steady state” is an important term in pharmacokinetics, but it can often seem a bit abstract and confusing to many. Here is how I define steady state: When the rate of drug input is equal to the rate of drug elimination, steady state has been achieved. Another way to think of this is imagine a … Continued

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