Volume of Distribution (Vd) Explained Simply
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[Glossary · How doses act in the body]

Volume of distribution

Also called Vd, apparent volume of distribution, Vss · Reviewed

Definition: Volume of distribution (Vd) links the total amount of drug in the body to its level in the blood: Vd = amount in the body ÷ plasma concentration. It is not a real space. It is the volume the drug would need to fill to give the measured level, which shows how much leaves the blood for tissues.

High vs low Vd

StatPearls explains that a drug with a high Vd leaves the blood and spreads widely into tissues, while a drug with a low Vd tends to stay in the plasma. Its examples span a huge range: warfarin at 0.14 L/kg and chloroquine at 235 L/kg.

Volume of distribution on current US labels.
ProductVd on the labelNote
Ozempic (semaglutide)About 12.5 LMore than 99% bound to albumin
Mounjaro (tirzepatide)About 10.3 L99% bound to albumin
Egrifta SV (tesamorelin)4.8 L/kg (healthy adults)Single 1.4 mg dose

Worked example: per-kilogram figures

Turning L/kg into liters

  1. Vd in L/kg is multiplied by body weight. For a 70 kg adult and tesamorelin: 4.8 × 70 = 336 L.
  2. 336 L is several times the size of the whole body, which is why Vd is called apparent. It tells you the drug moves out of the blood into tissue.
  3. Semaglutide's 12.5 L is small by comparison. The label notes it is more than 99% bound to albumin, a blood protein.

These are averages from study groups. Individual numbers vary with body size, kidney and liver function and the product itself.

Why it matters when you track doses

StatPearls notes that a drug with a high Vd may need a larger dose to reach a given blood level, and a low Vd a smaller one. Together with clearance, it shapes the half-life. You will not use it day to day, but it helps explain why two drugs can behave so differently.

Read more on Dose Track: Semaglutide guide · Tesamorelin guide

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
ClearanceClearance is the volume of blood plasma the body clears of a drug per unit of time, so it is written as… Half-lifeHalf-life is the time it takes for the amount of a drug in your body to fall by half. After one half-life,… Loading doseA loading dose is a larger dose, or a short series of doses, given at the start of treatment to reach a… PK/PD (pharmacokinetics and pharmacodynamics)Pharmacokinetics (PK) is what the body does to a drug: absorbing it, spreading it around, breaking it down…

Frequently asked questions

Is volume of distribution a real volume?+
No. It is a calculated, apparent volume. It can be far larger than the body itself when a drug moves mostly into tissues.
What does a low volume of distribution mean?+
The drug tends to stay in the blood plasma rather than spreading into tissues. Semaglutide and tirzepatide have Vd figures of about 10 to 13 liters on their labels.

Sources

  1. Bisht S, Chauhan V, Patel P. Clinical Significance of Volume of Distribution in Pharmacotherapy. StatPearls 2026. PMID 31424864
  2. Ozempic (semaglutide) US prescribing information, sections 2 and 12.3, DailyMed
  3. Mounjaro (tirzepatide) US prescribing information, sections 2 and 12.3, DailyMed
  4. Egrifta SV (tesamorelin) US prescribing information, sections 1, 2, 11 and 12, DailyMed

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