The Active Pharmaceutical Ingredient (API) is the component in a drug product that provides the pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease. Simply put, the API is the substance responsible for the therapeutic effect of the medicine. For instance, in a paracetamol tablet, the paracetamol compound itself is the API.
In the formulation of a finished drug product, the API is combined with excipients (or inactive ingredients), which are substances used to stabilize the drug, bulk it up, or aid in its absorption. The development and manufacturing of the API is a complex chemical or biological process governed by strict Good Manufacturing Practice (GMP) guidelines to ensure its quality, purity, and potency. The journey of a drug begins with the discovery and optimization of an API; its structure, mechanism of action, and stability are critical data points that must be thoroughly characterized throughout the entire Drug Discovery and development lifecycle.
