Articles

Extractables & leachables: the genotoxicity dimension of E&L

4 min read

A drug product is only as safe as everything it touches on the way to the patient. Container-closure systems, single-use manufacturing components, delivery devices and packaging can all shed trace chemicals into a medicine — and some of those chemicals can be DNA-reactive. This is why extractables and leachables (E&L) assessment so often turns on a single, decisive endpoint: genotoxicity.

Because mutagenic substances carry extraordinarily low acceptable limits, the genotoxic risk from a leachable frequently sets the tightest specification in the whole safety assessment. This article explains the E&L genotoxicity workflow, the thresholds involved, and the standards that govern it.

Key points

Extractables vs leachables

Extractables can migrate under forced conditions; leachables actually migrate into the product in real use.

Genotoxicity often drives it

Mutagenic leachables have the lowest acceptable limits, so they usually dominate the risk assessment.

The TTC anchor

DNA-reactive leachables are controlled to the ICH M7 threshold of 1.5 µg/day.

Predict, then confirm

(Q)SAR screens each identified compound; testing confirms where structure raises a flag.

Extractables and leachables: the difference that matters

Extractables are substances that can be pulled out of a material under exaggerated conditions (aggressive solvents, heat, time) — a worst-case inventory of what might migrate. Leachables are the substances that actually do migrate into the drug product (or reach the patient) under real, normal-use conditions. Extractables studies map the hazard space; leachables studies confirm the real-world exposure.

The safety question for each identified compound is the same one that runs through all of genetic toxicology: could this substance damage DNA?

At a glance

1.5 µg/day

The ICH M7 threshold applied to DNA-reactive (mutagenic) leachables

AET

Analytical Evaluation Threshold — the level above which compounds must be identified and assessed

USP 1663 / 1664

The framework guidance for extractables and leachables

ISO 10993-18

Chemical characterisation for the medical-device side of E&L

The genotoxicity workflow in E&L

  • Chemical characterisation — an extractables study identifies and semi-quantifies the compounds present, down to the Analytical Evaluation Threshold (AET).
  • Toxicological assessment — each identified compound is evaluated, with mutagenicity assessed first because it carries the lowest limits.
  • (Q)SAR screening — structure-based prediction (per ICH M7) flags DNA-reactive alerts.
  • Control or confirm — flagged compounds are either controlled below the relevant threshold (e.g. 1.5 µg/day) or tested (Ames, OECD 471) to resolve the alert.
  • Leachables study — real-use migration is measured on the actual product to confirm exposures against the limits.

The standards that govern it

E&L genotoxicity sits at the intersection of several frameworks: USP <1663> and <1664> for extractables and leachables, ICH M7 for DNA-reactive impurities and the TTC, and — on the medical-device side — ISO 10993-18 (chemical characterisation), ISO 10993-17 (toxicological risk / allowable limits) and ISO 10993-33 (genotoxicity). Combination products and single-use systems draw on all of them, which is why an integrated approach pays off.

Frequently asked questions

What are extractables and leachables?

Extractables are substances that can migrate from a material under exaggerated conditions; leachables are those that actually migrate into the drug product or reach the patient under normal use. Extractables map the hazard; leachables confirm real exposure.

Why does genotoxicity matter so much in E&L?

Mutagenic (DNA-reactive) leachables carry very low acceptable limits — anchored to the ICH M7 threshold of 1.5 µg/day — so they frequently set the tightest specification in the entire safety assessment.

How are mutagenic leachables assessed?

Identified compounds are screened by (Q)SAR for DNA-reactive structural alerts; flagged compounds are either controlled below the relevant threshold or confirmed by testing such as the Ames assay, then verified against real leachables data.

Which standards apply to E&L genotoxicity?

USP <1663>/<1664> for extractables and leachables, ICH M7 for DNA-reactive impurities, and — for medical devices — ISO 10993-18, -17 and -33.

De-risk your materials with GenEvolutioN

GenEvolutioN brings genotoxicity expertise to extractables and leachables programmes — (Q)SAR assessment of identified compounds and GLP confirmatory testing — so mutagenic risk is caught early and controlled with confidence.

See how this connects to genotoxicity fundamentals and impurity control, or talk to our team.