Examples
| Drug | VD | Comments |
|---|---|---|
| Warfarin | 8 L | Reflects a high degree of plasma protein binding. |
| Theophylline, Ethanol | 30 L | Represents distribution in total body water. |
| Chloroquine | 15000 L | Shows highly lipophilic molecules which sequester into total body fat. |
| NXY-059 | 8 L | Highly charged hydrophilic molecule. |
What is a high volume of distribution?
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 is volume of distribution pharmacology?
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].
Which type of drugs are distributed?
Based on the molecular structure, drugs have variable distribution in different types of tissues such as fat, muscle, and brain. Unlike other tissues, the brain and testes are unique, as they contain membrane barriers making a drug significantly less susceptible to distribution.
Why does digoxin have a high volume of distribution?
Digoxin has a large volume of distribution, due to its high affinity for skeletal and cardiac muscles, intestines and kidney.
What is the volume of distribution of chloroquine?
The drug is extensively distributed, with a volume of distribution of 200 to 800 L/kg when calculated from plasma concentrations and 200 L/kg when estimated from whole blood data (concentrations being 5 to 10 times higher). Chloroquine is 60% bound to plasma proteins and equally cleared by the kidney and liver.
What is the volume of distribution of warfarin?
Warfarin is essentially completely absorbed, reaching a maximum plasma concentration between 2 and 6 hours. It distributes into a small volume of distribution (10 L/70kg) and is eliminated by hepatic metabolism with a very small clearance (0.2 L/h/70kg).
What is plasma drug concentration?
Definition: Plasma concentration refers to the concentration of an agent in the plasma which is derived from full blood. Plasma concentrations are used to define major PK and PK/PD parameters.
What is Vd of a drug?
Simply defined, the volume of distribution is the volume of plasma that would be necessary to account for the total amount of drug in the patient’s body, if that drug were present throughout the body at the same concentration as found in the plasma.
What is peak plasma level?
Cmax is the highest inhibitor concentration reached in the blood in vivo and is an approximation of the inhibitor concentration (I) at the enzymes in the liver. From: Drug-Like Properties (Second Edition), 2016.
How are drugs distributed?
Distribution in pharmacology is a branch of pharmacokinetics which describes the reversible transfer of a drug from one location to another within the body. Once a drug enters into systemic circulation by absorption or direct administration, it must be distributed into interstitial and intracellular fluids.
What are drug reservoirs?
Some drugs accumulate in certain tissues (for example, digoxin accumulates in heart and skeletal muscles), which can also act as reservoirs of extra drug. These tissues slowly release the drug into the bloodstream, keeping blood levels of the drug from decreasing rapidly and thereby prolonging the effect of the drug.
What factors affect volume of distribution?
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.
Where 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.
What is the apparent volume of distribution of digoxin?
Digoxin is widely distributed throughout body tissues and has a high apparent volume of distribution (about 6L/kg). Although most of the digoxin in the body is in skeletal muscle it is found in highest concentrations in the heart, kidneys and brain.
What drug class is digoxin?
Digoxin belongs to the class of medicines called digitalis glycosides. It is used to improve the strength and efficiency of the heart, or to control the rate and rhythm of the heartbeat. This leads to better blood circulation and reduced swelling of the hands and ankles in patients with heart problems.
What is the volume of distribution of heparin?
Volume of Distribution
| Drug | V (l, 70 kg) |
|---|---|
| Heparin | 5 |
| Sulfisoxazole | 11.2 |
| Phenobarbital | 38.5 |
| Ethosuxumide | 49 |
How does volume of distribution affect clearance?
Volume of distribution per se has no effect on clearance or on average steady-state blood levels. Drug binding in nonvascular regions(i.e. tissue binding) seems to be of limited importance except as a determinant of half-life.
What is the brand name of chloroquine?
Chloroquine
| Clinical data | |
|---|---|
| Trade names | Aralen, other |
| Other names | Chloroquine phosphate |
| AHFS/Drugs.com | Monograph |
| License data | US DailyMed: Chloroquine US FDA: Chloroquine |
Why does warfarin have a low volume of distribution?
ECF ECF = Extra Cellular Fluid Warfarin has a very small apparent volume (based on total concentration) because it binds extensively to plasma proteins.
What is the brand name of diazepam?
Depsol Forte – Intas [Diazepam]
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