Drug Substance For Early Clinical Phase Initiation

By Lieven Van Vooren, Scientific Director, Arno Vermote, Senior CMC Writer

Preparing a drug substance for early clinical development demands more than meeting phase‑appropriate specifications. Unexpected impurities—particularly nitrosamines—can undermine toxicology results, delay clinical entry, and trigger costly rework if identified too late. A proactive, science‑driven approach to impurity risk assessment helps identify potential formation and carryover risks before a synthesis route is locked in. By understanding how raw materials, reaction conditions, cross‑contamination, and process design influence impurity profiles, development teams can adapt routes early and avoid downstream analytical and regulatory complications.

Regulatory expectations increasingly require documented risk assessments, confirmatory testing when needed, and clearly defined mitigation strategies. Sensitive, product‑specific analytical methods are essential to detect trace‑level impurities at extremely low acceptable limits. Integrating synthesis design, analytical development, and regulatory documentation from the outset strengthens control over drug substance quality. These practices enable faster, more reliable initiation of toxicology programs and first‑in‑human studies while protecting long‑term development timelines and clinical confidence.