Maintenance Dose

What is this formula?

The Maintenance Dose (MD) calculates the amount of drug that must be administered at each dosing interval to maintain a desired steady-state concentration.

When to use it

Use this formula when designing long-term dosing regimens and adjusting drug therapy based on pharmacokinetic parameters.

Example

Data:

Css = 15 mg/L

Cl = 4 L/h

tau = 12 h

F = 0.75

Formula:

MD = (Css × Cl × tau) / F

Substitution:

MD = (15 × 4 × 12) / 0.75

Result:

MD = 960 mg

Applications

- Chronic drug therapy

- Therapeutic drug monitoring

- Antibiotic dosing

- Antiepileptic treatment

- Clinical pharmacokinetics

Note

This formula assumes linear pharmacokinetics and steady-state conditions. Drug interactions, nonlinear elimination, organ dysfunction, and patient variability may significantly affect the actual maintenance dose required.