Plasma Stability Assay

Plasma stability is an important part of the ADME screening cascade. Instability of test compounds in plasma can lead to rapid in vivo clearance and poor pharmacokinetics.  Certain types of chemical classes are particularly susceptible to hydrolysis by plasma-residing enzymes and a plasma stability screen can alert you to such structural liabilities. Moreover, if a pro-drug is designed to be cleaved in plasma, this stability assessment can give valuable kinetic information, assisting in ranking the development candidates.

Experimental Procedure:

Test and control compounds are incubated in plasma at 37 °C for 2 hours. Aliquots of plasma are removed at chosen timepoints and proteins precipitated by the addition of an organic solvent. Supernatants are diluted further, and depletion of test compound is monitored using Ultra-High Performance Liquid Chromatography (UHPLC)-MS/MS. Example data is shown in Figure 1 and Table 1.

Data Analysis:

Extracts are analysed using Waters Acquity UHPLC TQ-S, TQS-micro or TQ-XS instruments. Triple quadrupole mass spectrometers, operated in multiple reaction monitoring (MRM) mode, provide accurate quantification with excellent sensitivity, selectivity and reproducibility.   

Log linear plots of compound depletion allows half-lives (t1/2) of compounds to be estimated:


The results are reported in Excel file format as t1/2 (min), including standard error of mean (SEM). Any relevant comments about compound stability/solubility/binding are also included in the report.

Turnaround time from receipt of the compounds to release of data is typically less than 2 weeks.

Plasma Stability key information
Plasma Stability key information
*Other options available upon request

Figure 1: Compound stability in mouse plasma following incubation.

Table 1: Table showing calculated half-lives for the same four compounds.