The F.D.A. has approved three drugs for opioid treatment — buprenorphine (often known by the brand name Suboxone), methadone and naltrexone (known by the brand name Vivitrol) — and says they are safe and effective combined with counseling and other support. But the agency said it would soon publish two guidances, recommendations for drugmakers, on the issue.

One encourages the development of new, longer-acting formulations of existing drugs for opioid treatment. The other, which was described in detail to The Times, said new drugs would be eligible for approval that don’t end addiction but help with aspects of it, such as cravings, or overdoses, with the goal remaining complete abstinence.

“We will permit an endpoint that shows substantial reductions but does not require the patient to be totally clean at every visit if the measurements are fairly frequent,” a senior F.D.A. official said.

The official also said the F.D.A. was seeking medications that can help patients function better and can be helpful when used in combination with therapy and other social support, even if on their own the medications don’t completely end addiction. Under the new guidelines, patients and their families will have input in assessing how useful a drug is.

“You could envision different MATs where the different treatments are addressing different aspects of what underlies the addiction, and helping people lead productive lives free from addiction to opioids, even in situations where they still might require replacement therapy,” the official said.

Addiction experts were cautious in their praise of the plan, which should be released in March.

“The F.D.A. should keep companies focused on major clinical improvement for patients,” said Yngvild Olsen,medical director of the Institutes for Behavior Resources in Baltimore. “A more thoughtful approach to measuring meaningful clinical improvement could expand treatment options, but there is a danger; subjective outcomes that are neither here nor there could encourage the development of products of questionable value.”

And Dr. Andrew Kolodny, a director of opioid policy research at Brandeis University, said that the F.D.A. was smart to look for new treatments but that the biggest problem now in treatment wasn’t lack of effective medication, but lack of access.

“We already have an effective treatment that people aren’t getting access to,” he said. “The primary challenge is getting it to people.”