What is the meaning of volume of distribution?
The volume of distribution (Vd) is a pharmacokinetic parameter representing an individual drug’s propensity to either remain in the plasma or redistribute to other tissue compartments.
What is a normal volume of distribution?
If the volume is between 7 4 and 15 7 L, the drug is thought to be distributed throughout the blood (plasma and red blood cells). If the volume of distribution is larger than 42, the drug is thought to be distributed to all tissues in the body, especially the fatty tissue.
What is formula for volume of distribution?
The volume of distribution is useful in estimating the dose required to achieve a given plasma concentration as A = C ·Vd, with A = amount of drug in the body ( ≈ dose, shortly after administration) and C = plasma concentration. Variation of Vd mainly affects the peak plasma concentration of the drug.
How do you work out Vd?
The simplest conceptual way to determine Vd is to administer a dose of drug, measure concentration over time and extrapolate the concentrations to “zero-time” to find the initial concentration. Then use the known dose (DL) and concentration (C0) to calculate Vd.
Why is volume of distribution important?
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 is the volume of distribution of digoxin?
Digoxin is roughly 30 percent protein bound in the plasma and has a large volume of distribution (VD) of nearly 7 L/kg in healthy adults.
What affects VD?
The major determinants of Vd are drug properties which affect protein binding and tissue binding. These consist of molecule size, charge, pKa, and the lipid/water partition coefficient.
What is volume of distribution in pharmacology?
In pharmacology, the volume of distribution (VD, also known as apparent volume of distribution, literally, volume of dilution) is the theoretical volume that would be necessary to contain the total amount of an administered drug at the same concentration that it is observed in the blood plasma.
What is volume of drug distribution?
Volume of distribution (Vd), represents the apparent volume into which the drug is distributed to provide the same concentration as it currently is in blood plasma. It is calculated by the amount of the drug in the body divided by the plasma concentration [19].
What two factors can change the volume of distribution?
Factors that affect the volume of distribution include plasma protein binding, obesity, edema, and tissue binding.
How is digoxin distributed?
Digoxin is extensively distributed in the tissues, as reflected by the large volume of distribution. High concentrations are found in the heart and kidneys, but the skeletal muscles form the largest digoxin storage. The half-life of elimination in healthy persons varies between 26 and 45 hours.
How do you calculate volume of distribution?
The correct answer is D. The volume of distribution of a drug can be determined using the following equation: t1/2 = (0.693 x Vd)/CL. Therefore, 10 hours = (0.693 x Vd)/(4.0 L/hour), 40 hours = 0.693 x Vd,
What is the maximum daily dose of vancomycin?
-Some experts recommend: 15 mg/kg IV once, followed by 60 mg/kg per day continuous infusion. -Maximum dose: 2 g/dose. -Duration of treatment: At least 2 weeks. Comment: Surgical evaluation is recommended for patients with septic thromboses, empyema, and/or abscesses.
What is the Max dose for vancomycin?
Loading doses are based on a patient’s total body weight without need for determining vancomycin clearance. A dose of approximately 25mg/kg with a maximum dose of 2000mg is suggested, or the table below can be used.
What is the peak level of vancomycin?
Therapeutic drug monitoring. Target ranges for serum vancomycin concentrations have changed over the years. Early authors suggested peak levels of 30 to 40 mg/l and trough levels of 5 to 10 mg/l, but current recommendations are that peak levels need not be measured and that trough levels of 10 to 15 mg/l or 15 to 20 mg/l,…