APPARENT VOLUME OF DISTRIBUTION
CONCENTRATION of drug in the plasma and tissues depends on: (2)
amount of drug SYSTEMICALLY ABSORBED
volume in which the drug is DISTRIBUTED
it is used to ESTIMATE the extent of drug distribution in the body
APPARENT VD
- it represents the result of dynamic drug distribution between the plasma and the tissues and accounts for the mass balance of the drug in the body
APPARENT VD
APPARENT VOLUME OF DISTRIBUTION
- it relates the ____ to the ____
plasma drug concentration to the amount of drug present in the body
it is NOT a true anatomic or physical volume
APPARENT VD
- term needed to RELATE drug concentration in the SYSTEM (human body) to the amount of drug present in THAT system)
VOLUME
the VOLUME of the system may be ESTIMATED if the amount of drug added to the system and the drug concentration after equilibrium in the system are ____
known
FORMULA for VOLUME (L)
amt of drug added to the system (dose) / drug concentration in the system after equilibrium (mg/L)
- volume in PLASMA
- is a HYPOTHETICAL VOLUME into which a drug INITIALLY distributes upon administration
this compartment can be thought of as the BLOOD in vessels and tissues which are highly perfused by blood
CENTRAL COLUME (Vc)
FORMULA for CENTRAL VOLUME (Vc)
dose / max concentration
- is the SUM of ALL tissue spaces outside the central compartment
PERIPHERAL VOLUME (Vt)
ALL drugs INITIALLY distribute into the ____ before distributing into the ____
INITIALLY - smaller Vc
then into the peripheral volume
- is the volume of fluid REQUIRED to contain the total amount of drug in the body at the same concentration as that present in the plasma
VOLUME OF DISTRIBUTION (VD)
MINIMUM volume of distribution must be ____ to the plasma volume
EQUAL
VOLUME OF DISTRIBUTION
- drug is distributed in the INTRAcellular fluid
25-30L
in COMPARTMENT MODEL, ____ is the volume of distribution determined at steady state when the drug concentration in the tissue compartment is at EQUILIBRIUM with the drug concentration in the plasma compartment
VOLUME OF DISTRIBUTION AT STEADY STATE
in ____, Volume of Distribution of Steady State is the volume of distribution determined at steady state when the drug concentration in the tissue compartment is at EQUILIBRIUM with the drug concentration in the plasma compartment
in ____, Volume of Distribution of Steady State is the volume of distribution determined at steady state when the drug concentration in the tissue compartment is at EQUILIBRIUM with the drug concentration in the plasma compartment
COMPARTMENT MODEL
- this model DOES NOT follow two compartment model
- it DEPENDS ln blood perfusion
PHYSIOLOGIC MODEL
VOLUME OF DISTRIBUTION AFTER an IV bolus injection can be calculated using the equation
Dose / plasma
VOLUME OF DISTRIBUTION
- drug is distributed in the WHOLE-BODY FLUID
aprrox 40L
VOLUME OF DISTRIBUTION
- drug is distributed in the EXTRAcellular fluid
10-20L
- in
VOLUME OF DISTRIBUTION
- drug is confined to CIRCULATORY SYSTEM SOLELY
approx. 5L
