A generic drug is a preparation that imitates a drug whose patent has expired. The active ingredients of generic drugs are identical to drugs that are already available on the pharmaceutical market. This allows different companies to manufacture and offer the generic drug. Nevertheless, the quality and efficacy must be verified and accepted by the generic manufacturer with the appropriate regulatory authorities. This can be done by means of bioequivalence proofs, which prove the therapeutic equivalence between the generic and the original, provided that the speed and quantity of absorption reaches approximately the same level as the original. There must also be no deviations from the original in the dosage form of the preparation – only the form may change. Generics may use additional excipients and use other manufacturing processes that optimize the duration of efficacy dosing and patient tolerability. Generics represent the less expensive version and are therefore increasingly chosen by statutory health insurers. The lower price is justified by the fact that no research effort had to be made and production or small optimizations could be started directly. Increased competition after the expiration of a patent also results in a lower price for the generic product.