The US state of Missouri will become the fourth US state to implement a real-time cold medicine tracking system, known as the National Precursor Log Exchange or NPLEx.

NPLEx is designed to help in the battle against illegal methadone labs without creating an unnecessary and burdensome prescription mandate for over-the-counter cold and allergy medicines containing PSE.

Under the system all retailers are required to submit over-the-counter cold and allergy medicine purchases to the national real-time tracking system through NPLEx.

A customer’s photo identification is scanned by the pharmacy and the data is entered into a secure, web-based portal, through which a message is instantly sent to the retailer when a transaction exceeds the legal limit.

By adopting NPLEx as its e-tracking programme, Missouri launches a pioneering effort to block illegal PSE purchases store by store, city by city and state by state, officials said.

The NPLEx system is now connected to nearly a third of the nation’s pharmacies and ensures that, within participating states, criminals cannot move from store to store to purchase an illegal quantity of these cold medicines.

There are two other states expected to join within the next few weeks and there are 11 states with active legislation that would connect them to Kentucky.