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The growth of the generic drug market worldwide may turn out to be a long-term trend, experts say, as a number of studies show a stable decline in prescriptions of brand-name drugs last year.

In the United States alone, prescriptions of generic drugs increased by 8 percent last year, while those of brand-name drugs plummeted 21 percent. In addition, the total value spent in 2012 on brand-name drugs in the country dropped for the first time in many years, Investor Place reported.

The IMS Institute for Healthcare Informatics predicts that in five years, generic drugs will account for 87 percent of the prescribed drugs in the United States. However, the balance in total spending is unlikely to change drastically, as generic medicines are usually sold at a fraction of the price of the brand-name alternatives.

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There are several generic drug makers that are faring very well at the moment and experts predict that they are likely to keep gaining ground on the U.S. market over the next few years. One of these is Actavis, which has a very stable portfolio and some of its products are extremely popular. Its paracetamol, for instance, generated a turnover of over $6 billion in 2012.

Another major generic drug maker is Teva Pharmaceutical. It produces more than 350 drugs, including several non-generic brands. The company is generally considered the biggest player on the market and is set to cement its leading position in the next few years, Investor Place said.