Forking lemma

Characteristic	Description	Example value	Symbol	Formula
Dose	Amount of drug administered.	500 mg	$D$	Design parameter
Dosing interval	Time between drug dose administrations.	24 h	$\tau$	Design parameter
Cmax	The peak plasma concentration of a drug after administration.	60.9 mg/L	$C_{\text{max}}$	Direct measurement
tmax	Time to reach Cmax.	3.9 h	$t_{\text{max}}$	Direct measurement
Cmin	The lowest (trough) concentration that a drug reaches before the next dose is administered.	27.7 mg/L	$C_{{\text{min}},{\text{ss}}}$	Direct measurement
Volume of distribution	The apparent volume in which a drug is distributed (i.e., the parameter relating drug concentration to drug amount in the body).	6.0 L	$V_{\text{d}}$	$={\frac {D}{C_{0}}}$
Concentration	Amount of drug in a given volume of plasma.	83.3 mg/L	$C_{0},C_{\text{ss}}$	$={\frac {D}{V_{\text{d}}}}$
Elimination half-life	The time required for the concentration of the drug to reach half of its original value.	12 h	$t_{\frac {1}{2}}$	$={\frac {ln(2)}{k_{\text{e}}}}$
Elimination rate constant	The rate at which a drug is removed from the body.	0.0578 h−1	$k_{\text{e}}$	$={\frac {ln(2)}{t_{\frac {1}{2}}}}={\frac {CL}{V_{\text{d}}}}$
Infusion rate	Rate of infusion required to balance elimination.	50 mg/h	$k_{\text{in}}$	$=C_{\text{ss}}\cdot CL$
Area under the curve	The integral of the concentration-time curve (after a single dose or in steady state).	1,320 mg/L·h	$AUC_{0-\infty }$	$=\int _{0}^{\infty }C\,\operatorname {d} t$
			$AUC_{\tau ,{\text{ss}}}$	$=\int _{t}^{t+\tau }C\,\operatorname {d} t$
Clearance	The volume of plasma cleared of the drug per unit time.	0.38 L/h	$CL$	$=V_{\text{d}}\cdot k_{\text{e}}={\frac {D}{AUC}}$
Bioavailability	The systemically available fraction of a drug.	0.8	$f$	$={\frac {AUC_{\text{po}}\cdot D_{\text{iv}}}{AUC_{\text{iv}}\cdot D_{\text{po}}}}$
Fluctuation	Peak trough fluctuation within one dosing interval at steady state	41.8 %	$\%PTF$	$={\frac {C_{{\text{max}},{\text{ss}}}-C_{{\text{min}},{\text{ss}}}}{C_{{\text{av}},{\text{ss}}}}}\cdot 100$ where $C_{{\text{av}},{\text{ss}}}={\frac {1}{\tau }}AUC_{\tau ,{\text{ss}}}$