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How to Calculate Maximum Daily Dose of a Drug

Maximum daily dose is an important information for a doctor and a patient also. This information help to prevent overdose of any drug. Generally daily dose calculation depends on the body weight of patient and recommended/prescribed dose mg/kg. 

If you want to calculate the dose of a medication, you need to use the following equation:

Dose = weight * dosage

But maximum daily dose is recommended based on the clinical data from animal study. Sometimes toxicological data also available for few drugs from post-marketing study. Which also help to define the maximum daily dose of a drug.

For your information: Maximum Daily Dose Database (MDDD)

On the other hand pharmacokinetic parameters varies from patient to patient which effect on drug doses for a patient. Alterations in medication absorption, volume of distribution and drug distribution in the body, protein binding, biotransformation, and kidney excretion may result in the accumulation of potentially toxic components and over dosage. It is therefore critical to adjust the doses of drugs that are excreted primarily by the kidneys appropriately. Drug dosing will use either the calculated or measured creatinine clearance or estimated GFR formula, which will allow for safer use of potent drug.


There is also available a FDA Maximum (Recommended) Daily Dose (FDAMDD) database based on data obtained from the FDA Source and Main Citation (Matthews et al., 2004). For further explanation of Source-specific fields, a user is encouraged to consult the listed references and information provided on the main DSSTox FDAMDD SDF Download Page.


  • Defined Daily Dose (DDD): is the average maintenance dose per day for a drug used for its main indication in adults.

  • Maximum Daily Dose (MDD): is the highest amount of allowable drug or medicine for a patient with consistent safety.

  • Prescribed Daily Dose (PDD): is defined as the average dose prescribed according to a representative sample of prescriptions.

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