What is ADMET?

Learning objectives

After reading this article you will be able to:

  • Explain each letter of ADMET
  • Name common assays used for each property
  • Understand why ADMET is assessed early

A molecule can bind its target perfectly and still fail as a drug if it never reaches the target, disappears too fast, or harms the patient. ADMET groups the properties that decide this.

LetterQuestionTypical measurements
AbsorptionDoes it get into the bloodstream?Solubility, permeability (PAMPA, Caco-2), oral bioavailability
DistributionWhere does it go in the body?Plasma protein binding, volume of distribution, brain penetration
MetabolismHow quickly is it broken down, and into what?Liver microsome or hepatocyte stability, cytochrome P450 (CYP) inhibition
ExcretionHow is it cleared?Renal and biliary clearance, half-life
ToxicityIs it safe at the needed dose?hERG channel inhibition (heart rhythm risk), cytotoxicity, genotoxicity (Ames), liver toxicity

Why it is assessed early

Poor pharmacokinetics and toxicity are major reasons drug candidates fail. Problems are far cheaper to fix during hit-to-lead and lead optimization, when chemists can still change the scaffold, than after a candidate has been nominated. Modern projects therefore run fast in-vitro ADMET assays alongside potency testing from the start.

Predicting ADMET computationally

Machine-learning models trained on large assay datasets predict many ADMET endpoints from structure, typically using fingerprints or graph neural networks. Predictions are most reliable for molecules similar to the training data, so they are good for prioritising which compounds to make and test — less so for compounds in unusual chemical space, such as many beyond rule of five molecules.

Balancing potency and properties

Changes that improve potency often add size and lipophilicity, which tend to worsen solubility, metabolic stability and toxicity. Efficiency metrics such as ligand efficiency and lipophilic ligand efficiency (pIC50 − logP) help teams improve potency without paying for it in ADMET.

Last updated October 31, 2026

Keep learning

What is scaffold hopping? Scaffold hopping replaces the core of an active molecule with a different chemical framework that keeps the key interactions, to gain new IP, better properties or easier synthesis. What is fragment linking? Fragment linking joins two small fragments that bind neighbouring sites on a protein with a linker, aiming for a molecule that binds much more tightly than either fragment. What are covalent drugs? Covalent drugs form a chemical bond with their target protein, usually through a reactive "warhead" that attacks a nearby amino acid such as cysteine.

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