How can i select slope while calculating T 1/2 in NCA. How to input units for dose.

how to select slope to accuratly calculate the T 1/2. How to input units for dose.

Answer 1

[Anshuman]

Hi Vijaya,

When calculating the half-life (T1/2) of a drug in non-compartmental analysis (NCA), the selection of the slope is crucial because it directly affects the accuracy of the half-life estimation. The slope is determined from the terminal phase of the drug concentration-time curve.

To select the slope for the terminal phase you typically:

1. Identify the terminal phase of the plasma concentration-time curve by visual inspection or using statistical methods to ensure that the phase follows linear kinetics on a semi-log plot (log concentration vs. time).
2. Perform a linear regression on the data points in the terminal phase to determine the slope (λz) of the line.
3. Calculate the half-life using the following relationship: [ T1/2 = ln(2) / lambda_z ]

Regarding the dosing units, when you perform NCA, it is essential to maintain consistency in the units used for dosing and concentration measurements.