In order for similar preparations containing the same active ingredients in the same ratio to be equivalent to each other, they must be pharmaceutically bioequivalent. By definition, a drug must be effective, safe, affordable and of acceptable cost. 

One of the most important factors affecting the success of treatment applications with drugs is the bioavailability of the drug, that is, the amount that can reach the target area from the application site. It is determined by bioavailability studies whether the expected therapeutic response from systemically effective drugs can be obtained. Therefore, the health authorities that authorize the production and sale of drugs require generic drugs to prove that they are bioequivalent to the original drugs. 

The need for better quality, cheaper and, most importantly, safer drugs will only be possible with bioavailability and bioequivalence studies.