Template:DoseConcentrationClearance

Pharmacokinetic metrics

Characteristic	Description	Symbol	Unit	Formula	Worked example value
Dose	Amount of drug administered.	$D$	$\mathrm {mol}$	Design parameter	500 mmol
Dosing interval	Time between drug dose administrations.	$\tau$	$\mathrm {h}$	Design parameter	24 h
Cmax	The peak plasma concentration of a drug after administration.	$C_{\text{max}}$	$\mathrm {mmol/L}$	Direct measurement	60.9 mmol/L
tmax	Time to reach Cmax.	$t_{\text{max}}$	$\mathrm {h}$	Direct measurement	3.9 h
Cmin	The lowest (trough) concentration that a drug reaches before the next dose is administered.	$C_{{\text{min}},{\text{ss}}}$	$\mathrm {mmol/L}$	Direct measurement	27.7 mmol/L
Cavg	The average plasma concentration of a drug over the dosing interval in steady state.	$C_{{\text{av}},{\text{ss}}}$	$\mathrm {h\times mmol/L}$	${\frac {AUC_{\tau ,{\text{ss}}}}{\tau }}$	55.0 h×mmol/L
Volume of distribution	The apparent volume in which a drug is distributed (i.e., the parameter relating drug concentration in plasma to drug amount in the body).	$V_{\text{d}}$	$\mathrm {L}$	${\frac {D}{C_{0}}}$	6.0 L
Concentration	Amount of drug in a given volume of plasma.	$C_{0},C_{\text{ss}}$	$\mathrm {mmol/L}$	${\frac {D}{V_{\text{d}}}}$	83.3 mmol/L
Absorption half-life	The time required for 50% of a given dose of drug to be absorbed into the systemic circulation.[1]	$t_{{\frac {1}{2}}a}$	$\mathrm {h}$	${\frac {\ln(2)}{k_{\text{a}}}}$	1.0 h
Absorption rate constant	The rate at which a drug enters into the body for oral and other extravascular routes.	$k_{\text{a}}$	$\mathrm {h} ^{-1}$	${\frac {\ln(2)}{t_{{\frac {1}{2}}a}}}$	0.693 h−1
Elimination half-‍life	The time required for the concentration of the drug to reach half of its original value.	$t_{{\frac {1}{2}}b}$	$\mathrm {h}$	${\frac {\ln(2)}{k_{\text{e}}}}$	12 h
Elimination rate constant	The rate at which a drug is removed from the body.	$k_{\text{e}}$	$\mathrm {h} ^{-1}$	${\frac {\ln(2)}{t_{{\frac {1}{2}}b}}}={\frac {CL}{V_{\text{d}}}}$	0.0578 h−1
Infusion rate	Rate of infusion required to balance elimination.	$k_{\text{in}}$	$\mathrm {mol/h}$	$C_{\text{ss}}\cdot CL$	50 mmol/h
Area under the curve	The integral of the concentration-time curve (after a single dose or in steady state).	$AUC_{0-\infty }$	$\mathrm {M} \cdot \mathrm {s}$	$\int _{0}^{\infty }C\,\operatorname {d} t$	1,320 h×mmol/L
		$AUC_{\tau ,{\text{ss}}}$	$\mathrm {M} \cdot \mathrm {s}$	$\int _{t}^{t+\tau }C\,\operatorname {d} t$
Clearance	The volume of plasma cleared of the drug per unit time.	$CL$	$\mathrm {m} ^{3}/\mathrm {s}$	$V_{\text{d}}\cdot k_{\text{e}}={\frac {D}{AUC}}$	0.38 L/h
Bioavailability	The systemically available fraction of a drug.	$f$	Unitless	${\frac {AUC_{\text{po}}\cdot D_{\text{iv}}}{AUC_{\text{iv}}\cdot D_{\text{po}}}}$	0.8
Fluctuation	Peak–trough fluctuation within one dosing interval at steady state.	$\%PTF$	$\%$	$100{\frac {C_{{\text{max}},{\text{ss}}}-C_{{\text{min}},{\text{ss}}}}{C_{{\text{av}},{\text{ss}}}}}$ where $C_{{\text{av}},{\text{ss}}}={\frac {AUC_{\tau ,{\text{ss}}}}{\tau }}$	41.8%

Template documentation

See also

• Pharmacokinetics § Metrics

References

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