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Maintenance Dose Calculator

Work out maintenance dose instantly with clear inputs, formula shown and shareable results.

About Maintenance Dose Calculator

Multiplies clearance, target concentration and dosing interval, then divides by bioavailability, which is the standard maintenance dose relationship.

Formula

Maintenance dose

Dose = clearance (L/h) x target concentration (mg/L) x interval (h) / bioavailability; continuous infusion rate = clearance x target concentration

Worked example

With the default values below, Maintenance Dose Calculator returns Maintenance dose per interval of 666.7. Change any input above and every figure here is recalculated in your browser.

Inputs used

Drug clearanceaccepts 0.05–200 L/h
5 L/h
Target average concentrationaccepts 0.1–500 mg/L
10 mg/L
Dosing intervalaccepts 1–72 h
12 h
Bioavailabilityaccepts 5–100
90

Results

Maintenance dose per interval
666.7 mg
Total daily dose
1,333.3 mg
Equivalent continuous infusion rate
50.00 mg/h

Step by step

  1. 1Values used
  2. 2Maintenance dose
  3. 3Maintenance dose per interval= 666.7 mg
  4. 4Total daily dose= 1,333.3 mg
  5. 5Equivalent continuous infusion rate= 50.00 mg/h

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

Why does clearance drive the maintenance dose?

At steady state the rate in must equal the rate out, and the rate out is clearance times concentration.

What changes in renal impairment?

Clearance falls, so either the dose is reduced or the interval lengthened to keep the same average concentration.

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