FAQ: What Does A Large Volume Of Distribution Mean?

The larger the volume of distribution, the more likely that the drug is found in the tissues of the body. The smaller the volume of distribution, the more likely that the drug is confined to the circulatory system.

What does a high volume of distribution mean?

Definition/Introduction A drug with a high Vd has a propensity to leave the plasma and enter the extravascular compartments of the body, meaning that a higher dose of a drug is required to achieve a given plasma concentration. (High Vd -> More distribution to other tissue)

What does volume of distribution tell you?

The volume of distribution (Vd) specifies how widely the drug is distributed in the body. It represents the apparent volume into which the drug is dissolved. The larger is the Vd, the less it is able to reach the tissues it is expected to reach and exert its pharmacological effect.

What is the significance of volume of distribution?

ABSTRACT: Volume of distribution is one of the most important pharmacokinetic properties of a drug candidate. It is a major determinant of half-life and dosing frequency of a drug. For a similar log P, a basic molecule will tend to exhibit higher volume of distribution than a neutral molecule.

What causes a high volume of distribution?

Volume of distribution may be increased by kidney failure (due to fluid retention) and liver failure (due to altered body fluid and plasma protein binding). Conversely it may be decreased in dehydration.

Is it good to have a high volume of distribution?

The larger the volume of distribution, the more likely that the drug is found in the tissues of the body. The smaller the volume of distribution, the more likely that the drug is confined to the circulatory system.

How does volume of distribution affect clearance?

Volume of distribution per se has no effect on clearance or on average steady-state blood levels. Although changes in tissue binding will affect partition coefficient and apparent volume of distribution, such changes will have no effect on average steady-state blood levels of either total or free drug.

What drugs have a large volume of distribution?

Some drugs (e.g. tolbutamide, phenytoin, gentamicin, warfarin) are known to have small volumes of distribution (0.1–1 L/kg) while others (e.g. meperidine, propranolol, digoxin ) are known to have large volumes of distribution (1–10 L/kg).

What is the significance of the volume of distribution in compartment based analysis of drugs?

FIGURE 1-18. Two-compartment model. Volume of distribution (V) is an important indicator of the extent of drug distribution into body fluids and tis- sues. V relates the amount of drug in the body (X) to the measured concentration in the plasma (C).

How does volume of distribution affect half life?

3.2. Half-life is dependent on both clearance and volume of distribution, such that a decrease in clearance, as might be seen with a CYP1A2 or CYP2C19 substrate, or an increase in volume of distribution will prolong the half-life and lead to a longer dosage interval.

Which type of drug has fairly high apparent volume of distribution?

Its apparent volume of distribution is close to total body water. Because it does not bind to plasma proteins this suggests it does not bind extensively to tissues either. Digoxin has a very large apparent volume of distribution – several times bigger than the typical human physical volume of 70 L.

Is volume of distribution constant?

The volume of distribution is a proportionality constant, relating the total amount of drug present in the organism to its plasma concentration at the same moment.

Does volume of distribution increase half life?

Half life is increased by an increase in the volume of distribution and increased by a decrease in the rate of clearance.

What clearance determines?

Clearance is the parameter that determines total systemic exposure to drug, which is simply the ratio of dose/clearance. Total body clearance is the sum of all processes by which drugs are removed from the body or inactivated, primarily renal excretion and metabolism.

What is volume in medicine?

[vol´ūm] the space occupied by a substance or a three-dimensional region; the capacity of such a region or of a container. blood volume the plasma volume added to the red cell volume; see also blood volume.

How does protein binding affect drug distribution?

Protein-binding may affect drug activity in one of two ways: either by changing the effective concentration of the drug at its site of action or by changing the rate at which the drug is eliminated, thus affecting the length of time for which effective concentrations are maintained.