WASHINGTON — A fast-growing category of prescription drugs that are among the most expensive on the market could, for the first time, face competition from generic competitors under the health-care bills moving through Congress.

Biologic drugs, those made from living organisms instead of from chemicals, are increasingly used to treat arthritis, cancer, diabetes and other diseases. They’re also more expensive for drug makers to produce and for patients to buy. The breast cancer drug Herceptin can cost $48,000 a year, and the rheumatoid arthritis drug Remicade can cost about $20,000.

Indianapolis-based Eli Lilly and Co., which last year completed construction on a $1 billion biotech campus in Indianapolis, is the nation’s fifth-largest biologic drug maker. The company has nine biologic drugs on the market, including insulin and drugs to treat osteoporosis and sepsis.

The bills would create an easier approval system for what are called “bio-similars.” The system would be similar to the expedited approval process for generic versions of traditional drugs, with one exception: While traditional drugs get five years of market exclusivity after their patent expires, biologic drugs would get 12 years.

That makes a difference to taxpayers, because the government is one of the largest purchasers of prescription drugs. It also matters to patients such as Virginia’s Anne Collins, who just started taking a biologic drug for the psoriatic arthritis and psoriasis that can be so painful it’s difficult for her to walk. The drug costs about $2,000 a month.

“The biologics have proven to be miracle workers for many people,” Collins said. Although her insurance covers all but $35 of the monthly cost, she’s worried she’ll eventually hit her plan’s lifetime limit on benefits. And she wonders what people who don’t have insurance do.

“This isn’t even an option for them,” she said. “For people who can’t afford it, there needs to be a generic.”

The 12-year period of market exclusivity for biologics that’s in the bills could save consumers and the government an estimated $25 billion over 10 years, according to the Congressional Budget Office. A shorter exclusivity period would save more but also take more out of drug makers’ profits.

Lilly’s biologic drugs account for about 30 percent of its sales, and about half of the drugs in Lilly’s late-stage development pipeline are biologic.

Critics say the issue is a prime example of how the drug industry isn’t contributing enough to the health-care overhaul, despite its commitment to giving up $80 billion over 10 years.

“This is the low-hanging fruit,” said Mark Merritt, head of the Pharmaceutical Care Management Association, which represents companies that manage drug benefit programs for employers. “If you can’t get this right in terms of cost control, what can you get right?”

The Federal Trade Commission has said biologic drugs don’t need a longer exclusivity period than regular drugs because biologics are more difficult and costlier to duplicate. That means makers of brand-name drugs will keep much of their market share — and profits — even after facing competition, according to the commission.