WASHINGTON — Federal regulators on Friday approved the first alternative version of the second-best selling drug in the world, Humira, the blockbuster injection used to treat rheumatoid arthritis and other inflammatory diseases.

The Food and Drug Administration cleared a near-copy of the drug, dubbed Amjevita, developed by Amgen Inc. Regulators approved the drug for more than a half-dozen conditions listed on the original drug’s label, including severe psoriasis and Crohn’s diseases.

Humira posted sales of nearly $15 billion in 2015 and was for many years the top-selling prescription drug in the world, according to data from IMS Health.

It’s the fourth time that the FDA has formally approved a so-called biosimilar, the industry term for a lower-cost version of a biotech drug. Biosimilar drugs, long available in Europe, are thought to have the potential to generate billions in savings for the U.S. health system.

But currently only one biosimilar cleared by the FDA approval pathway is actually on the market in the U.S.