Parameter

Definition

Ae

Amount of drug excreted with urine.

air excretion

% of drug dose excreted with expired air.

alpha

Distribution rate constant

amount excreted by dialysis

Amount of drug excreted by dialysis.

amount excreted in milk

Amount of drug excreted in milk.

AUC

Area under the curve (drug concentration-time curve).

AUMC

Area under the first moment curve.

Brain/plasma ratio

Ratio of the concentration of drug in brain and plasma.

bile excretion

% of drug dose excreted with bile.

bioavailability

Fraction of administered dose of unchanged drug that reaches the systemic circulation. Absolute bioavailability compares the bioavailability (estimated as the area under the curve, or AUC) of the active drug in systemic circulation following non-intravenous administration, with the bioavailability of the same drug following intravenous administration.

blood cells binding

Drug binding to blood cells.

Blood/plasma ratio

Blood/plasma ratio

Blood/serum ratio

Blood/serum ratio

C

Drug or metabolite concentration at the time point.

Cavg

Mean (average) concentration.

CL

Clearance. Parameter to quantify drug elimination. Volume of plasma that would contain the amount of drug excreted per minute or, alternatively, the volume of plasma that would have to lose all of the drug that it contains within a unit of time (usually 1 min) to account for an observed rate of drug elimination. Thus, clearance expresses the rate or efficiency of drug removal from the plasma but not the amount of drug eliminated. "Systemic clearance" is usually used for for intravenous administration. "Oral clearance" is in use for oral drug administration.

CL/F

Clearance/Bioavalability ratio.Can be defined as apparent clearance

CLd

Dialysis clearance.

CLnr

Non renal clearance.

CLnr/F

Non renal clearance/Bioavalability ratio.

CLpl

Plasma clearance.

CLpl/F

Plasma clearance/Bioavalability ratio.

CLr

Renal clearance.

CLr/F

Renal clearance/Bioavalability ratio.

CLss

Steady state clearance.

CLss/F

Steady state clearance/Bioavalability ratio.

CLt

Total clearance.

CLt/F

Total clearance/Bioavalability ratio.

Cmax

Maximal concentration of the drug in blood or tissue after its administration to the organism.

Cmin

Minimal concentration or through plasma concentration.

CSF/plasma ratio

Cerebrospinal fluid/plasma ratio

CSF/serum ratio

Cerebrospinal fluid/serum ratio

dialysis excretion

% of drug dose excreted by dialysis.

Enantiomeric ratio

Ratio between enantiomeric molecules of drug (racemic mixture).

enterohepatic excretion

% of drug dose excreted via entherohepatic pathway.

excretion rate

Amount of drug eliminated in time unit.

Fa

Fraction of dose administered, absorbed through the gut wall. Can be used only for extravascular administration.

fecal excretion

% of drug dose excreted with feces.

Fetal/maternal ratio

Fetal/maternal ratio. Ratio of the concentration of drug in fetal and mother blood.

fu

Unbound fraction or free fraction of drug in blood.

k10

Intercompartmental rate constant (central compartment ->elimination)

k12

Intercompartmental rate constant (central compartment ->peritheral compartment)

k13

Intercompartmental rate constant (compartment 1->compartment 3)

k21

Intercompartmental rate constant (peritheral compartment->central compartment )

k31

Intercompartmental rate constant (compartment 3->compartment 1)

Ka

Absorption constant, only used for per os administration. Characterize the absorption phase, associated with T1/2abs (Ka = 0.693/ t1/2abs).

Kel

Elimination rate constant. Describes the decrease in the plasma concentration of a drug over time from a first-order plot. Kel = 0.693/T1/2el

Kp

Partition coefficient between tissues (liver/whole blood, liver/plasma:).

LAUC

Log of AUC.

LCmax

Log of Cmax.

MAT

Mean absorption time, estimates of the rate of absorption.

Metabolic ratio

Ratio of one or several metabolites on drug.

Metabolic stability

% of dose found as unchanged (not metabolized) drug.

Metabolic transformation

% of dose transformed into metabolite.

milk excretion

% of drug dose excreted with milk.

Milk/plasma ratio

Milk/plasma ratio

Milk/serum ratio

Milk/plasma ratio

MRT

Mean residence time.

plasma protein binding

Drug binding to plasma proteins.

Plasma/blood ratio

Plasma/blood ratio

Q

Inter-compartment clearance (between the central and peripheral compartments).

RAC

Accumulation ratio. Accumulation occurs when the drug from previous doses has not been completely removed.

radioactivity recovery

% of radioactivity recovered after administration of radiolabeled drug.

RBC/plasma ratio

Red blood cells/plasma ratio.

serum protein binding

Drug binding to serum proteins.

sweat excretion

Amount of drug excreted in sweet

T1/2

Half-life. Time necessary to decrease the drug concentration of in an organism by 50%.

T1/2abs

Half-life of absorption. The time taken for half of the drug waiting to be absorbed to reach the systemic circulation.

T1/2alpha2

Half-life of distribution.

Time to steady state

Time necessary to reach steady state. Can be used only for repeated drug administration.

tissue distribution

% of dose found of tissue.

Tlag

Absorption lag time, the onset of the plasma curve.

Tlast

Time to the last measurable drug level in organism.

Tmax

Time to reach Cmax. Time necessary to reach the maximal drug concentration in an tissue after its administration to the organism.

total excretion

Total % of dose excreted by all possible routes.

urinary excretion rate

Amount of drug eliminated in time unit with urine.

urine excretion

% of drug dose excreted with urine.

Vc

Volume of distribution, central compartment (for two-, three-compartmental models).

Vc/F

Volume of distribution, central compartment/bioavailability ratio.

Vd

Volume of distribution, apparent volume into which a drug distributes in the body.

Vd/F

Volume of distribution/bioavailability ratio.

Vss

Volume of distribution at steady state.

Vss/F

Volume of distribution at steady state/bioavailability ratio.

Vz

Volume of distribution, peripheral compartment (for two-, three-compartmental models).

Vz/F

Volume of distribution, peripheral compartment/bioavailability ratio.

cumulative excretion

Amount of drug excreted by all routes.

amount excreted by air

Amound of drug excreted with expired air.

amount excreted in feces

Amount of drug excreted with feces.

LCavg

Log of Cavg.

LCmin

Log of Cmin.

Q/F

Inter-compartment clearance (between the central and peripheral compartments)/Bioavalability ratio.

Tmin

Time to reach Cmin.

bile excretion rate

Amount of drug eliminated in time unit with bile

%absorbed

% of drug dose absorbed after administration.

CLd/F

Dialysis clearance/Bioavalability ratio.

fraction of dose excreted

Fraction of dose excreted