Parameters

Rsq

R2

R Squared

unitless

Goodness of fit statistic for the terminal (log-linear) phase between the linear regression and the data

Rsq_adjusted

R2ADJ

R Squared Adjusted

unitless

Goodness of fit statistic for the terminal elimination phase, adjusted for the number of points used in the estimation of λz

Corr_XY

CORRXY

Correlation Between TimeX and Log ConcY

unitless

Correlation between time (X) and log concentration (Y) for the points used in the estimation of λz

No_points_lambda_z

LAMZNPT

Number of Points for Lambda z

unitless

Number of points considered in the λz regression

Lambda_z

LAMZ

Lambda z

1/time

First order rate constant associated with the terminal (log-linear) portion of the curve. Estimated by linear regression of time vs. log concentration

Lambda_z_lower

LAMZLL

Lambda z Lower Limit

time

Lower limit on time for values to be included in the λz calculation

Lambda_z_upper

LAMZUL

Lambda z Upper Limit

time

Upperlimit on time for values to be included in the λz calculation

HL_Lambda_z

LAMZHL

Half-Life Lambda z

time

Terminal half-life
= ln(2)/Lambda_z

Lambda_z_intercept

–

–

unitless

Intercept found during the regression for (\lambda_z\), i.e. value of the regression (in log-scale) at time 0, i.e. the regression writes
log(Concentration) = -Lambda_z*t+Lambda_z_intercept

Span

–

–

unitless

Ratio between the sampling interval of the measurements used for the λz and the terminal half-life
= (Lambda_z_upper – Lambda_z_lower)*Lambda_z/ln(2)

Tlag

TLAG

Time Until First Nonzero Conc

time

Tlag is the time prior to the first measurable (non-zero) concentration. Tlag is 0 if the first observation after the last dose is not 0 or LOQ. The value is set to 0 for non extravascular input.

T0

time

Time of the dose

Dose

amount

Amount of the dose

N_Samples

–

–

unitless

Number of samples in the individuals.

C0

C0

Initial Conc

amount/volume

If a PK profile does not contain an observation at dose time (C0), the following value is added
Extravascular and Infusion data. For single dose data, a concentration of zero.  For steady-state, the minimum observed during the dose interval.
IV Bolus data. Log-linear regression of first two data points to back-extrapolate C0.

Tmax

TMAX

Time of CMAX

time

Time of maximum observed concentration.
– For non-steady-state data, the entire curve is considered.
– For steady-state data, Tmax corresponds to points collected during a dosing interval.
If the maximum observed concentration is not unique, then the first maximum is used.

Cmax

CMAX

Max Conc

amount/volume

Maximum observed concentration, occurring at Tmax. If not unique, then the first maximum is used.

Cmax_D

CMAXD

Max Conc Norm by Dose

1/volume

Maximum observed concentration divided by dose.
Cmax_D = Cmax/Dose

Tlast

TLST

Time of Last Nonzero Conc

time

Last time point with measurable concentration

Clast

CLST

Last Nonzero Conc

amount/volume

Concentration of last time point with measurable concentration

AUClast

AUCLST

AUC to Last Nonzero Conc

time⋅amount/volume

Area under the curve from the time of dosing to the last measurable positive concentration. The calculation depends on the Integral method setting.

AUClast_D

AUCLSTD

AUC to Last Nonzero Conc Norm by Dose

time/volume

Area under the curve from the time of dosing to the last measurable concentration divided by the dose.
AUClast_D = AUClast/Dose

AUMClast

AUMCLST

AUMC to Last Nonzero Conc

time²⋅amount/volume

Area under the moment curve (area under a plot of the product of concentration and time versus time) from the time of dosing to the last measurable concentration.

MRTlast

MRTIVLST

MRT Intravasc to Last Nonzero Conc

time

[if intravascular] Mean residence time from the time of dosing to the time of the last measurable concentration, for a substance administered by intravascular dosing.
MRTlast_iv = AUMClast/AUClast – TI/2, where TI represents infusion duration.

MRTlast

MRTEVLST

MRT Extravasc to Last Nonzero Conc

time

[if extravascular] Mean residence time from the time of dosing to the time of the last measurable concentration for a substance administered by extravascular dosing.
MRTlast_ev = AUMClast/AUClast – TI/2, where TI represents infusion duration.

AUCall

AUCALL

AUC All

time⋅amount/volume

Area under the curve from the time of dosing to the time of the last observation.
If the last concentration is positive AUClast=AUCall.
Otherwise, AUCall will not be equal to AUClast as it includes the additional area from the last measurable concentration down to zero or negative observations.

AUCINF_obs

AUCIFO

AUC Infinity Obs

time⋅amount/volume

AUC from Dosing_time extrapolated to infinity, based on the last observed concentration.
AUCINF_obs = AUClast + Clast/Lambda_z

AUCINF_D_obs

AUCIFOD

AUC Infinity Obs Norm by Dose

time/volume

AUCINF_obs divided by dose
AUCINF_D_obs = AUCINF_obs/Dose

AUC_PerCentExtrap_obs

AUCPEO

AUC %Extrapolation Obs

%

Percentage of AUCINF_obs due to extrapolation from Tlast to infinity.
AUC_%Extrap_obs = 100*(1- AUClast / AUCINF_obs)

AUC_PerCentBack_Ext_obs

AUCPBEO

AUC %Back Extrapolation Obs

%

Applies only for intravascular bolus dosing. the percentage of AUCINF_obs that was due to back extrapolation to estimate C(0).

AUMCINF_obs

AUMCIFO

AUMC Infinity Obs

time²⋅amount/volume

Area under the first moment curve to infinity using observed Clast
AUMCINF_obs = AUMClast + (Clast/Lambda_z)*(Tlast + 1.0/Lambda_z)

AUMC_PerCentExtrap_obs

AUMCPEO

AUMC % Extrapolation Obs

%

Extrapolated (% or total) area under the first moment curve to infinity using observed Clast
AUMC_%Extrap_obs = 100*(1- AUMClast / AUMCINF_obs)

MRTINF_obs

MRTIVIFO

MRT Intravasc Infinity Obs

time

[if intravascular] Mean Residence Time extrapolated to infinity for a substance administered by intravascular dosing using observed Clast
MRTINF_obs_iv = AUMCINF_obs/AUCINF_obs- TI/2, where TI represents infusion duration.

MRTINF_obs

MRTEVIFO

MRT Extravasc Infinity Obs

time

[if extravascular] Mean Residence Time extrapolated to infinity for a substance administered by extravascular dosing using observed Clast
MRTINF_obs_ev = AUMCINF_obs/AUCINF_obs

Vz_F_obs

VZFO

Vz Obs by F

volume

[if extravascular] Volume of distribution associated with the terminal phase divided by F (bioavailability)
Vz_F_obs = Dose/Lambda_z/AUCINF_obs

Cl_F_obs

CLFO

Total CL Obs by F

volume/time

[if extravascular] Clearance over F (based on observed Clast)
Cl_F_obs = Dose/AUCINF_obs

Vz_obs

VZO

Vz Obs

volume

[if intravascular] Volume of distribution associated with the terminal phase
Vz_obs= Dose/Lambda_z/AUCINF_obs

Cl_obs

CLO

Total CL Obs

volume/time

 [if intravascular] Clearance (based on observed Clast)
Cl_obs = Dose/AUCINF_obs

Vss_obs

VSSO

Vol Dist Steady State Obs

volume

 [if intravascular] An estimate of the volume of distribution at steady state based last observed concentration.
Vss_obs = MRTINF_obs*Cl_obs

Clast_pred

–

–

amount/volume

Clast_pred = exp(Lambda_z_intercept- Lambda_z* Tlast)
The values alpha (corresponding to the y-intercept obtained when calculating λz) and lambda_z are those values found during the regression
for λz

AUCINF_pred

AUCIFP

AUC Infinity Pred

time⋅amount/volume

Area under the curve from the dose time extrapolated to infinity, based on the last predicted concentration, i.e., concentration at the final observation time estimated using the linear regression performed to estimate λz.
AUCINF_pred = AUClast + Clast_pred/Lambda_z

AUCINF_D_pred

AUCIFPD

AUC Infinity Pred Norm by Dose

time/volume

AUCINF_pred divided by dose
= AUCINF_pred/Dose

AUC_PerCentExtrap_pred

AUCPEP

AUC %Extrapolation Pred

%

Percentage of AUCINF_pred due to extrapolation from Tlast to infinity
AUC_%Extrap_pred = 100*(1- AUClast / AUCINF_pred)

AUC_PerCentBack_Ext_pred

AUCPBEP

AUC %Back Extrapolation Pred

%

Applies only for intravascular bolus dosing. The percentage of AUCINF_pred that was due to back extrapolation to estimate C(0).

AUMCINF_pred

AUMCIFP

AUMC Infinity Pred

time²⋅amount/volume

Area under the first moment curve to infinity using predicted Clast
AUMCINF_pred = AUMClast + (Clast_pred/Lambda_z)*(Tlast+1/Lambda_z)

AUMC_PerCentExtrap_pred

AUMCPEP

AUMC % Extrapolation Pred

%

Extrapolated (% or total) area under the first moment curve to infinity using predicted Clast
AUMC_%Extrap_pred = 100*(1- AUMClast / AUMCINF_pred)

MRTINF_pred

MRTIVIFP

MRT Intravasc Infinity Pred

time

[if intravascular] Mean Residence Time extrapolated to infinity for a substance administered by intravascular dosing using predicted Clast

MRTINF_pred

MRTEVIFP

MRT Extravasc Infinity Pred

time

[if extravascular] Mean Residence Time extrapolated to infinity for a substance administered by extravascular dosing using predicted Clast

Vz_F_pred

VZFP

Vz Pred by F

volume

[if extravascular] Volume of distribution associated with the terminal phase divided by F (bioavailability)
= Dose/Lambda_z/AUCINF_pred

Cl_F_pred

CLFP

Total CL Pred by F

volume/time

[if extravascular] Clearance over F (using predicted Clast)
Cl_F_pred = Dose/AUCINF_pred

Vz_pred

VZP

Vz Pred

volume

[if intravascular] Volume of distribution associated with the terminal phas
Vz_pred = Dose/Lambda_z/AUCINF_pred

Cl_pred

CLP

Total CL Pred

volume/time

[if intravascular] Clearance (using predicted Clast)
= Dose/AUCINF_pred

Vss_pred

VSSP

Vol Dist Steady State Pred

volume

[if intravascular] An estimate of the volume of distribution at steady state based on the last predicted concentration.
Vss_pred = MRTINF_pred*Cl_pred

AUC_lower_upper

AUCINT

AUC from T1 to T2

time⋅amount/volume

AUC from T1 to T2 (partial AUC)

AUC_lower_upper_D

AUCINTD

AUC from T1 to T2 Norm by Dose

time/volume

AUC from T1 to T2 (partial AUC) divided by Dose

CAVG_lower_upper

CAVGINT

Average Conc from T1 to T2

amount/volume

Average concentration from T1 to T2

Tau

–

time

The (assumed equal) dosing interval for steady-state data.

Ctau

CTAU

Conc Trough

amount/volume

Concentration at end of dosing interval.
If the observed concentration does not exist, the value is interpolated. It it cannot be interpolated, it is extrapolated using lambda_z. If lambda_z has not been computed, it is extrapolated as the last observed value.

Ctrough

CTROUGH

Conc Trough

amount/volume

Concentration at end of dosing interval.
If the observed concentration does not exist, the value is NaN.

AUC_TAU

AUCTAU

AUC Over Dosing Interval

time⋅amount/volume

The area under the curve (AUC) for the defined interval between doses (TAU). The calculation depends on the Integral method setting.

AUC_TAU_D

AUCTAUD

AUC Over Dosing Interval Norm by Dose

time/volume

The area under the curve (AUC) for the defined interval between doses (TAU) divided by the dose.
AUC_TAU_D = AUC_TAU/Dose

AUC_TAU_PerCentExtrap

–

–

%

 Percentage of AUC due to extrapolation in steady state.

 AUC_TAU_%Extrap = 100*(AUC [Tlast, tau] if Tlast<=tau)/AUC_TAU;

AUMC_TAU

AUMCTAU

AUMC Over Dosing Interval

time²⋅amount/volume

The area under the first moment curve (AUMC) for the defined interval between doses (TAU).

Vz_F

VZFTAU

Vz for Dose Int by F

volume

[if extravascular] The volume of distribution associated with the terminal slope following extravascular administration divided by the fraction of dose absorbed, calculated using AUC_TAU.
Vz_F =  Dose/Lambda_z/AUC_TAU 

Vz

VZTAU

Vz for Dose Int

volume

[if intravascular] The volume of distribution associated with the terminal slope following intravascular administration, calculated using AUC_TAU.
Vz =  Dose/Lambda_z/AUC_TAU 

CLss_F

CLFTAU

Total CL by F for Dose Int

volume/time

[if extravascular] The total body clearance for extravascular administration divided by the fraction of dose absorbed, calculated using AUC_TAU .
CLss_F =  Dose/AUC_TAU 

CLss

CLTAU

Total CL for Dose Int

volume/time

[if intravascular] The total body clearance for intravascular administration, calculated using AUC_TAU.
CLss =  Dose/AUC_TAU 

Cavg

CAVG

Average Concentration

amount/volume

AUCTAU divided by Tau.
Cavg = AUC_TAU /Tau

FluctuationPerCent

FLUCP

Fluctuation%

%

The difference between Cmin and Cmax standardized to Cavg, between dose time and Tau.
Fluctuation%  = 100.0* (Cmax -Cmin)/Cavg 

FluctuationPerCent_Tau

–

–

%

The difference between Ctau and Cmax standardized to Cavg, between dose time and Tau.
Fluctuation% _Tau  = 100.0* (Cmax -Ctau)/Cavg

Accumulation_Index

AILAMZ

Accumulation Index using Lambda z

unitless

Theoretical accumulation ratio: Predicted accumulation ratio for area under the curve (AUC) calculated using the Lambda z estimated from single dose data.
Accumulation_Index = 1.0/(1.0 -exp(-Lambda_z*Tau))

Swing

–

–

unitless

The degree of fluctuation over one dosing interval at steady state
Swing = (Cmax -Cmin)/Cmin

Swing_Tau

–

–

unitless

Swing_Tau = (Cmax -Ctau)/Ctau

Tmin

TMIN

Time of CMIN observation.

time

Time of minimum concentration sampled during a dosing interval.

Cmin

CMIN

Min Conc

amount/volume

Minimum observed concentration between dose time and dose time + Tau.

Cmax

CMAX

Max Conc

amount/volume

Maximum observed concentration between dose time and dose time + Tau.

MRTINF_obs

MRTIVIFO or MRTEVIFO

MRT Intravasc Infinity Obs or MRT Extravasc Infinity Obs

time

Mean Residence Time extrapolated to infinity using predicted Clast, calculated using AUC_TAU.

T0

time

Time of the last administered dose (assumed to be zero unless
otherwise specified).

Dose

–

–

amount

Amount of the dose

N_Samples

–

–

unitless

Number of samples in the individuals.

Tlag

TLAG

Time Until First Nonzero Conc

time

Midpoint prior to the first measurable (non-zero) rate.

Tmax_Rate

ERTMAX

Midpoint of Interval of Maximum ER

time

Midpoint of collection interval associated with the maximum observed excretion rate.

Max_Rate

ERMAX

Max Excretion Rate

amount/time

Maximum observed excretion rate.

Mid_Pt_last

ERTLST

Midpoint of Interval of Last Nonzero ER

time

Midpoint of collection interval associated with Rate_last.

Rate_last

ERLST

Last Meas Excretion Rate

amount/time

Last measurable (positive) rate.

AURC_last

AURCLST

AURC to Last Nonzero Rate

amount

Area under the urinary excretion rate curve from time 0 to the last
measurable rate.

AURC_last_D

AURCLSTD

AURC to Last Nonzero Rate Norm by Dose

unitless

The area under the urinary excretion rate curve (AURC) from time zero to the last measurable rate, divided by the dose.

Vol_UR

VOLPK

Sum of Urine Vol

volume

Sum of Urine Volumes

Amount_Recovered

amount

Cumulative amount eliminated.

Percent_Recovered

%

100*Amount_Recovered/Dose

AURC_all

AURCALL

AURC All

amount

Area under the urinary excretion rate curve from time 0 to the last rate. This equals AURC_last if the last rate is measurable.

AURC_INF_obs

AURCIFO

AURC Infinity Obs

amount

Area under the urinary excretion rate curve extrapolated to infinity, based on the last observed excretion rate.

AURC_PerCentExtrap_obs

AURCPEO

AURC % Extrapolation Obs

%

Percent of AURC_INF_obs that is extrapolated

AURC_INF_pred

AURCIFP

AURC Infinity Pred

amount

Area under the urinary excretion rate curve extrapolated to infinity, based on the last predicted excretion rate.

AURC_PerCentExtrap_pred

AURCPEP

AURC % Extrapolation Pred

%

Percent of AURC_INF_pred that is extrapolated

AURC_lower_upper

AURCINT

AURC from T1 to T2 (partial AUC)

amount

The area under the urinary excretion rate curve (AURC) over the interval from T1 to T2.

AURC_lower_upper_D

AURCINTD

AURC from T1 to T2 Norm by Dose 

unitless

The area under the urinary excretion rate curve (AURC) over the interval from T1 to T2 divided by Dose

Rate_last_pred

–

–

amount/time

The values alpha and Lambda_z are those values found during the regression
for lambda_z

SE_Cmax

amount/volume

Sample standard error of the concentration values at Tmax (standard deviation of the y-values at time Tmax divided by the square root of the number of observations at Tmax)

SE_AUClast

time⋅amount/volume

with

and

where:

• = time of last measurable (positive) mean concentration

• = number of individuals sampled at both times i and j

• = number of individuals sampled at time i

• = sample variance of concentrations at time i

• = sample covariance between concentrations and for all individuals k that are sampled at both times i and j

SE_AUCall

time⋅amount/volume

Same as SE_AUClast with m = last observation time

SE_Max_Rate

amount/time

Same as SE_Cmax with excretion rates

SE_AURC_last

amount

Same as SE_AUClast with excretion rates

SE_AURC_all

amount

Same as SE_AUCall with excretion rates