Microsomal & Plasma Stability Calculator
Calculate log-linear half-life, R², and microsomal CLint from parent remaining over time.
Microsomal mode reports t½ and CLint; plasma mode reports t½ and remaining parent.
Stability results
Enter a time series.
Use parent signal from the same analyte, matrix, and incubation conditions. Separately review the initial linear window, replicates, controls, cofactors, nonspecific loss, and analytical stability. This calculator does not apply hepatic scaling or predict in-vivo clearance.
Sources: NIH/NCATS Assay Guidance Manual; NIH Molecular Libraries Probe Reports.
Tool Guide
Definition
Microsomal & Plasma Stability Calculator — Regress the natural log of parent remaining percent against time to obtain the loss rate constant k and half-life t½ from a negative slope. Microsomal mode additionally calculates in-vitro intrinsic clearance from incubation volume and microsomal protein.
Purpose
(1) Cross-check t½ and CLint from microsomal stability assays (2) Summarize plasma-stability half-life and final parent remaining (3) Prevent min/hour and µL/mL unit errors (4) Prepare report values with log-linear fit R²
How to Use
① Choose microsomal or plasma mode. ② Paste a same-condition series as time,percent, one pair per line. ③ In microsomal mode, enter total incubation volume and total microsomal protein. ④ Copy t½, k, R², final remaining, and CLint. Use only the initial log-linear interval and review replicates, controls, cofactors, and nonspecific loss separately. Zero percent cannot enter a logarithmic regression.
Examples
Example) Parent remaining at 0, 10, 20, and 30 min is 100, 70.7107, 50, and 35.3553% → k=0.03466 min⁻¹, t½=20 min, R²=1 With 1 mL total incubation and 0.5 mg microsomal protein → CLint=69.3147 µL/min/mg Hepatic scaling and in-vivo clearance prediction are not included.