The Comparator Drug (also comparator product) is, in a controlled clinical trial, the product against which the investigational medicinal product (IMP) is compared. It may be a placebo (a dummy medication without active substance), an active comparator (an already authorised medicinal product), or a standard therapy.
The choice of comparator is decisive for the study design and regulatory acceptance: placebo-controlled trials are optimal for measuring efficacy but are ethically permissible only where no effective standard therapy exists. Actively controlled trials compare the investigational medicinal product with a standard therapy (e.g. in non-inferiority trials) and are frequently preferred from a regulatory perspective.
If the Comparator Drug is an authorised medicinal product, it must be specially procured, documented and, where necessary, packaged/masked (overencapsulation, double-dummy technique) for use in the clinical trial to ensure blinding. A Certificate of Analysis (CoA) is required. For CROs, comparator management (procurement, storage, blinding, distribution, cold chain) is a logistically demanding and quality-critical task. Regulatory reference: ICH-GCP E6(R2); EU GMP Annex 13.