Pharmacists in Missouri have kept paper records each time someone buys cold medicines containing pseudoephedrine since a law limited purchases of the medicine in 2005.

Blunt, in a written statement, called the electronic tracking an important new tool for law enforcement to attack meth. The Republican governor ceremonially signed the bill on Tuesday at the Joplin Police Department and in Jackson, Palmyra and suburban St. Louis.

Missouri has regularly led the country in meth busts, though it started dropping off immediately after the law was effective in 2005. That measure capped how much of the pseudoephedrine-based medicines people could buy and required pharmacists to ask buyers to show a photo identification.

The Highway Patrol said meth lab incidents started increasing last year. The patrol said part of the problem is that meth producers have been going to multiple pharmacies and buying the maximum amount at each.

Republican House sponsor Kenny Jones, a former county sheriff, said last month when the bill passed that most of the people buying the cold medicines at several pharmacies are doing it to feed their personal addictions.

Besides going after meth, the legislation also gives specially trained nurses more power. Advanced practice nurses will be able to write their own prescriptions for some controlled substances, including nausea and cough medicines and pain relievers like Vicodin.

Supporters of that provision said it might increase health care access, especially in rural areas where there are few doctors. The prescription authority would apply only to advanced-practice registered nurses who have agreements with doctors.

Nurses with advanced training have been allowed to prescribe some medicines in Missouri since 1993 but not those deemed to be controlled substances. According to the state nurses association, only Alabama, Florida and Missouri had barred such nurses from prescribing controlled substances.