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:
- 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).
- Perform a linear regression on the data points in the terminal phase to determine the slope (λz) of the line.
- 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.
