JEFFERSON CITY, Mo. (AP) — U.S. Sen. Claire McCaskill of Missouri is asking Gov. Eric Greitens to bring state lawmakers back to the Capitol to pass legislation for a prescription drug monitoring program.

McCaskill said in a Wednesday letter to Greitens that he should call a special legislative session to enact a prescription database.

Missouri is the only state without a drug-tracking program. Advocates say databases help doctors and pharmacists track when patients receive numerous addictive medications, such as opioids. Then physicians can provide addiction treatment if needed.

Some Missouri lawmakers have pushed back over privacy concerns about a database of patients' prescription information.

A proposal to create a drug monitoring program failed to pass in the legislative session that ended May 12.

McCaskill says she's "bitterly disappointed."