The manufacturer of the generic drug submits an Abbreviated New Drug Application (ANDA) to the FDA. This application includes data demonstrating the drug's bioequivalence to the brand-name drug, as well as information on its safety, efficacy, manufacturing process, and labeling.

The FDA reviews the ANDA to ensure that the generic drug meets the same quality, safety, and efficacy standards as the brand-name drug. This involves assessing the bioequivalence of the generic drug to the brand-name drug, as well as evaluating its manufacturing process and labeling.

If the FDA determines that the generic drug is bioequivalent to the brand-name drug and meets all other regulatory requirements, it approves the ANDA. This allows the manufacturer to market and distribute the generic drug in the United States.

Before granting final approval, the FDA may need to address any patent challenges or exclusivity rights associated with the brand-name drug. This can involve litigation between the generic manufacturer and the brand-name manufacturer to resolve patent disputes.

After the generic drug is approved and enters the market, the FDA continues to monitor its safety and efficacy through post-market surveillance programs. This helps ensure that any potential safety concerns are promptly identified and addressed. Overall, the process for a generic drug to enter the market in the U.S. involves rigorous evaluation by the FDA to ensure that it is safe, effective, and of high quality. This helps provide patients with access to affordable medications while maintaining stringent regulatory standards.