rickets is a nutritional disorder that can develop if you do not get enough vitamin d calcium or phosphate rickets leads to poor functioning of a bone s growth plate growing edge softened and weakened bones stunted growth and in severe cases skeletal deformities
Hence, a 20-year period of the patent usually gives manufacturers a chance to recoup the cost of developing a new drug. When a drug patent expires, any pharmaceutical company can manufacture and sell the drug. A drug, which is produced and distributed without patent protection is called a generic drug.
In general, drugs expiration date is 2-5 years from production date. FDA regulations do not require manufacturers to determine actual long-term drug potency and stability. For example, if a company chooses a two year expiration date, it does not have to test beyond that for prolonged effectiveness.