A blockbuster drug is a drug generating more than $1 billion of revenue for its owner each year.[3] The search for blockbusters has been the foundation of the R&D strategy adopted by big pharmaceutical companies, but this looks set to change. New advances in genomics, and the promise of personalized medicine, are likely to fragment the pharmaceutical market. A recent report from Urch Publishing estimated that about one third of the pharma market by value is accounted for by blockbusters. About 100 products are blockbusters. The top seller was Lipitor, a cholesterol-lowering medication marketed by Pfizer with sales of $12.2 billion.*
*)source:wiki
Generic drug is a medicine which is chemically equivalent to a brand-name product, but available under its generic chemical name. Generic drug is identical, or bio-equivalent to its branded drug equivalent in dosage form, safety, strength, route of administration, quality, performance characteristics and intended use. It is manufactured by the certified producer but not by the original drug’s producer. Generic drug can be issued when the brand-name equivalent’s patent expires. Upon original medicine’s patent expiration any pharmaceutical company can obtain a right on its production and purchase a chemical formula.