Clearance Calculator Guide
Clearance Calculator Guide
The Clearance calculator determines the volume of plasma cleared of drug per unit time — one of the most fundamental PK parameters.
When to Use This Tool
- Estimating drug elimination capacity
- Adjusting doses for renal or hepatic impairment
- Comparing clearance across patient populations
- Converting between CL and half-life
Input Parameters
| Parameter | Unit | Description | Typical Range |
|---|---|---|---|
| Dose | mg | Total dose administered | Varies by drug |
| AUC | mg·h/L | Area under the concentration-time curve | Varies |
| Bioavailability (F) | fraction | Fraction absorbed (1.0 for IV) | 0.0–1.0 |
Formula
CL = (F × Dose) / AUC
Where:
- CL = Clearance (L/h)
- F = Bioavailability (dimensionless, 0–1)
- Dose = Administered dose (mg)
- AUC = Area under the curve (mg·h/L)
Worked Example
1
Define parameters
- Dose = 500 mg (oral)
- AUC = 25 mg·h/L (from clinical data)
- F = 0.85 (literature value for this drug)
2
Apply the formula
CL = (0.85 × 500) / 25
3
Calculate
CL = 425 / 25 = 17.0 L/h
Interpreting Results
| CL Range | Interpretation | Clinical Action |
|---|---|---|
| < 5 L/h | Low clearance | Consider dose reduction |
| 5–20 L/h | Typical range | Standard dosing |
| > 20 L/h | High clearance | May need higher doses or shorter intervals |
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Tip
For weight-normalized clearance, divide by body weight (CL/kg). Normal renal clearance is approximately 120 mL/min (7.2 L/h) for creatinine.
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Important
Clearance values should always be interpreted in the context of the specific drug, patient population, and clinical scenario.
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