Question

what is the apparent volume of distribution? And what does it measure?

Answer 1

Apparent volume of distribution is the ratio of the dose available in the body and its biological fluid plasma concentration ,considering that distribution of particular drug between tissue space and plasma space is in equilibrium.

Example -in fat tissue ,the distribution of the drug is higher in tissue than the plasma ,therefore apparent volume of distribution is considered to be high.The volume of distribution varies due to changes in different factors such as - propertties of drug (molecualr size and charge of drug, solubility of drug),properties of body biological fluid(pH, body water volume ,protein level and dispalcement) physiological and pathological states(age,gender,pregnancy ,edemaand ascites) etc.

Therefore ,it measures the theoretical distribution of drug into the tissue and plasma compartment .