⚠️ Research Use Only. Not validated for clinical diagnostic use.
PK/PD Calculator
Pharmacokinetic and pharmacodynamic calculations: half-life, clearance, volume of distribution, AUC, loading dose, maintenance dose.
Elimination Half-life
First-order elimination: k = ln(C₀/Cₜ)/t, t½ = ln(2)/k
Results
Elimination rate constant k
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Half-life t½
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Clearance (CL)
CL = Dose / AUC
Results
Clearance CL
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Volume of Distribution (Vd)
Vd = Dose / C₀
Results
Volume of Distribution Vd
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AUC — Area Under Curve
Trapezoidal rule. Enter time/concentration pairs, one per line.
Results
AUC
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Loading Dose
Loading Dose = (Target Concentration × Vd) / Bioavailability
Results
Loading Dose
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Research use only — not for clinical dosing decisions. This is a first-order pharmacokinetic estimate; actual dosing requires patient-specific parameters and professional oversight.
Maintenance Dose
Maintenance Dose = (CL × Target Concentration × Dosing Interval) / Bioavailability
Results
Maintenance Dose
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Research use only — not for clinical dosing decisions. This is a first-order pharmacokinetic estimate; actual dosing requires patient-specific parameters and professional oversight.
PK Parameter Reference
| Parameter | Formula | Clinical meaning |
|---|---|---|
| Half-life (t½) | ln(2)/k | Time for concentration to halve |
| Elimination rate (k) | ln(C₀/Cₜ)/t | First-order elimination constant |
| Clearance (CL) | Dose/AUC | Volume cleared per unit time |
| Volume of distribution (Vd) | Dose/C₀ | Apparent volume of drug distribution |
| AUC | Trapezoidal rule | Total drug exposure over time |
Frequently Asked Questions
What is half-life?
The time required for plasma concentration to decrease by half during first-order elimination. t½ = 0.693/k where k is the elimination rate constant.
What is clearance?
Clearance is the volume of plasma completely cleared of drug per unit time. CL = Dose / AUC. Units: L/h or mL/min.
What is volume of distribution?
The theoretical volume that would be required to contain the total amount of drug at the same concentration as observed in plasma. Vd = Dose / C₀.
What is AUC?
Area Under the Curve of concentration vs. time. Represents total systemic drug exposure. Calculated here using the trapezoidal rule.
Loading vs maintenance dose?
Loading dose rapidly achieves target concentration. Maintenance dose replaces drug eliminated between doses to maintain steady-state.