Which act requires a drug to be tested to demonstrate its safety when following the label directions?

The Federal Food, Drug, and Cosmetic Act is the legislation that mandates that all drugs must be tested to ensure their safety when used according to the label directions. This act was established to protect public health by requiring rigorous evaluation of pharmaceuticals, including animal medications, before they can be marketed. It ensures that drugs are proven to have safe usage profiles and will not cause harm when consumers or veterinarians follow the provided instructions.

While the other options relate to various aspects of drug regulation and control, they do not specifically impose the requirement for safety testing based on label directions as outlined in the Federal Food, Drug, and Cosmetic Act. For instance, the Food and Drug Administration Modernization Act focuses more on improving the FDA's processes and expediting the approval of new drugs. The Controlled Substances Act addresses the regulation of narcotics and controlled substances to prevent abuse and ensure legal handling. The Animal Medicinal Drug Use Clarification Act pertains to specific usages and guidelines for drugs in veterinary medicine but does not directly enforce the general testing requirement for drug safety as stated in the Federal Food, Drug, and Cosmetic Act.