Use Elimination Half-Life when you need to compute the first-order elimination half-life as 0.693 times the volume of distribution divided by the clearance. Enter Volume of distribution and Clearance using the definitions and units below so the result can be reproduced.

Volume of distribution

Apparent volume of distribution; must be greater than zero.

Clearance

Total body clearance; must be greater than zero.

The published tool contract uses this rule: Compute the first-order elimination half-life as 0.693 times the volume of distribution divided by the clearance.

Elimination half-life

Elimination half-life in hours.

A ratio or percentage can conceal the scale of its numerator and denominator and becomes sensitive to measurement error when the denominator is small.

Retain the original Volume of distribution and Clearance values and their units alongside the result. Biological Half-Life is useful when you instead need to compute the elimination half-life from volume of distribution and clearance. Apparent Vd provides another view by helping you estimate volume of distribution as the systemically available dose (administered dose times bioavailability) divided by plasma concentration.

• Biological Half-Life

  Compute the elimination half-life from volume of distribution and clearance.

• Apparent Vd

  Estimate volume of distribution as the systemically available dose (administered dose times bioavailability) divided by plasma concentration.

• Steady-State Concentration

  Predict the average plasma concentration at steady state as the infusion rate times bioavailability divided by clearance.