Nearly two decades have passed since extractables and leachables became a primary consideration for qualifying packaging intended for pharmaceutical use. The complexity of medicines and associated delivery systems continues to evolve, challenging approaches for identifying and quantifying leachables. Regulatory guidance for extractables and leachables exists, but only provides general recommendations for ensuring patient safety. Diane Paskiet, Laura Stubbs and Heike Kofler at West Pharmaceutical Services provide an overview of extractable and leachable science, and discuss approaches, applications and risk-based strategies.