Clearance Rate

Also known as: CL · systemic clearance

Clearance (CL) is the volume of plasma your body fully clears of a drug per unit of time, usually given in liters per hour.

Clearance measures how efficiently your body removes a drug. It is a flow, such as liters per hour: the volume of plasma that would be completely emptied of drug each hour. The amount removed per hour equals clearance times concentration, so with constant clearance more drug is eliminated per hour when levels are high and less when they are low. That is what produces the exponential decline described by half-life.

Peptides are cleared differently from most small-molecule drugs. Enzymes that break down peptides are present throughout the body, so degradation is not limited to the liver and kidneys, and many small peptides are also filtered by the kidneys and broken down there. Liraglutide and semaglutide were designed to last longer in the body through reversible binding to albumin, via an attached fatty acid. Semaglutide's label reports an apparent clearance of about 0.05 L/h, with elimination by breakdown of the peptide backbone and of the fatty acid side chain.

Why it matters

Clearance controls total exposure: for a given bioavailability, AUC = F × Dose / CL, so halving clearance doubles exposure at the same dose. Together with volume of distribution, it also sets half-life, which decides how often a compound needs dosing and how long it lingers after you stop.

Clearance routes are compound-specific, so blanket advice can mislead. A common claim is that kidney function drives exposure for every peptide, yet the semaglutide label states that renal impairment does not affect its pharmacokinetics in a clinically relevant way, and only about 3% of a dose appears in urine as intact semaglutide. For research peptides without human pharmacokinetic data, the main clearance route in people has not been measured.

How to calculate it

From a study: divide the absorbed dose (F × dose) by the AUC.
From label values: plug the reported clearance and volume of distribution into the half-life formula to cross-check the stated half-life.
Keep units consistent: liters with L/h gives hours.

CL = F × Dose / AUC; t½ = 0.693 × Vd / CL

Worked example

Semaglutide label values: apparent Vd about 12.5 L, apparent clearance about 0.05 L/h. t½ = 0.693 × 12.5 / 0.05 = 8.66 / 0.05 ≈ 173 hours, and 173 / 24 ≈ 7.2 days, consistent with the label's 'about 1 week'. If clearance doubled to 0.10 L/h with the same Vd, t½ would halve to about 87 hours and AUC at the same dose would halve too.

Common mistakes

Confusing clearance (a volume per unit time) with the amount of drug eliminated per unit time.
Assuming every peptide is cleared mainly by the kidneys, or mainly by the liver.
Ignoring that SubQ labels report apparent clearance (CL/F), which has bioavailability built in.
Assuming a longer half-life always means lower clearance; a larger volume of distribution also lengthens half-life.
Applying a clearance value from an animal study to people.

Sources

ReviewPharmacokinetics and pharmacokinetic-pharmacodynamic correlations of therapeutic peptides. Clin Pharmacokinet, 2013. PMID 23719681.
ReviewThe Discovery and Development of Liraglutide and Semaglutide. Front Endocrinol (Lausanne), 2019. PMID 31031702.
Prescribing informationOZEMPIC (semaglutide) injection, for subcutaneous use: Prescribing Information. Novo Nordisk (FDA-approved labeling), 2026.

Page updated October 3, 2026. How we grade evidence: methodology.

Related Terms

Half-Life

Half-life (t½) is the time it takes for the concentration of a drug in your blood plasma to fall by half.

Volume of Distribution

Volume of distribution (Vd) is the volume a drug would have to fill, at its plasma concentration, to account for all the drug in your body.

AUC (Area Under Curve)

AUC (area under the curve) is your total exposure to a drug over time: the area under its blood concentration-time curve.

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