NCA Calculation Method

[ctuk]

Hello

I was wondering if there was a general rule for deciding which NCA calculation method to use.

From reading the help guide, I understand that Linear Up Log Down refers to the curve will always use linear when concentrations increases, regardless of whether it is before or after Cmax and that Linear Log Trapezoidal refers to linear curve as concentration increases, and log curve after Cmax.

In which type of scenario would you use Linear Up Log Down and Linear Log Trapezoidal.

Regards

CTUK

[Helmut_Schuetz]

HI CTUK,

@ctuk

From reading the help guide, I understand that Linear Up Log Down refers to the curve will always use linear when concentrations increases, regardless of whether it is before or after Cmax and that Linear Log Trapezoidal refers to linear curve as concentration increases, and log curve after Cmax.

Your understanding is almost correct. The Linear Log Trapezoidal log transforms all concentrations – even in the increasing part. C_max doesn’t play a role in any of the methods. IMHO, this makes only sense for a fast bolus.

For an EV administration or a slow infusion the lin-up/log-down is the method of choice.

There is one exception: If the PK follows to a good part (don’t ask me for a definition) Michaelis-Menten PK (i.e., in a lin/log plot the profile bends down), maybe the linear trapezoidal performs best.