Calculate a drug loading dose from the target concentration, volume of distribution, bioavailability and salt factor, including top-up doses.
About this tool
Loading dose from target concentration, volume of distribution and bioavailability.
How to use Loading Dose Calculator
- Enter the target concentration.
- Enter the volume of distribution per kg with weight, or in litres.
- Add bioavailability, salt factor and any current level for a top-up dose.
Worked example
A target of 15 mg/L with a Vd of 0.7 L/kg in a 70 kg patient needs a loading dose of 735 mg.
Why give a loading dose?
Drugs with long half-lives take 4–5 half-lives to reach steady state. A loading dose reaches the target level at once.
What is the salt factor?
The fraction of the product that is active drug, such as 0.92 for aminophylline as theophylline.
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