Loading Dose Calculator
Loading dose from target concentration, volume of distribution and bioavailability.
Enter your values to see the result.
Loading dose = (C_target − C_current) × Vd ÷ (F × S). For education and clinical decision support only. Results do not replace professional judgment, local protocols or the product information, so always verify doses and values before acting on them.
Continue your work
- Maintenance Dose Calculator — Keep the level at target afterwards.
- Pharmacokinetic Calculator — Estimate the volume of distribution.
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Clear instructions
Find steps, examples and limitations below.
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How to use the Loading Dose Calculator
Loading dose from target concentration, volume of distribution and bioavailability.
- 1 Enter the target concentration.
- 2 Enter the volume of distribution per kg with weight, or in litres.
- 3 Add bioavailability, salt factor and any current level for a top-up dose.
Example and practical tips
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.
Frequently asked questions
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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