A new Pennsylvania law allows authorities to immediately flag suspicious purchases of a common ingredient in over-the-counter sinus medications. The ingredient, pseudoephedrine, is also used to manufacture methamphetamine.

On July 9, Gov. Tom Corbett signed into law an amendment of the state's Controlled Substance, Drug, Device and Cosmetic Act.

The amendment links the state to the National Precursor Log Exchange system (NPLEx), a real-time electronic tracking system that monitors sales of the drug and allows authorities to immediately halt sales to anyone who exceeds the daily 3.6 gram, and 9 grams in 30 days, limit on pseudoephedrine purchases.

The government has for years had restrictions in place on the sale of the drug. Since 2006, federal law has required people who buy medications containing the drug, which is kept behind the counter, to present their driver's license or other identification and sign an electronic register, called the MethCheck portal, at the time of purchase. The requirements allowed authorities to match excessive pseudoephedrine purchases to meth manufacturers who travel from drugstore to drugstore in order to buy enough of the drug to make meth.

The amendment makes Pennsylvania the 29th state to join NPLEx.

According to the NPLEx website, the system is provided free of charge to police and state governments by the National Association of Drug Diversion Investigators. The system is fully paid for by manufacturers of medicines containing pseudoephedrine.

Because the NPLEx system provides real-time tracking, it stops meth manufacture in its tracks, and alerts authorities to alleged perpetrators.

Here's how it works: When a sale is entered into the system that would exceed the limit, NPLEx instantly sends the seller a message recommending denial of the sale, and law enforcement authorities are notified. However, the system does include a manual override in case the clerk feels threatened by the buyer.

The ability to instantly block sales of the drug is sorely needed, local lawmakers say. According to the U.S. Drug Enforcement Agency, the number of meth labs simple equipment and common chemicals used to make meth is increasing dramatically.

State senators David G. Argall and John Yudichak both supported the changes. State representatives Doyle Heffley, Mario Scavello, Jerry Knowles, Mike Tobash, Neal Goodman also signed on in support.

Efforts early Monday to reach Argall and Yudichak were unsuccessful.