Clinical trial supplies, specifically comparative agents as either investigational medicinal products or as non-investigational medicinal products, are a unique commodity. Although clinical trial supply sourcing is a small part of the overall clinical trial supply chain, its associated sourcing necessities have high-quality specifications. Lekishia White and Ann-Marie Huss at Multipharma Clinical Supplies Ltd provide an overview of how due diligence with regard to the fulfilment of these needs can negatively affect trial timelines, however, this can be mitigated depending on the clinical trial specifics and flexibility of requirements.