A Baxter International drug that had shown promise as an Alzheimer’s treatment failed to slow mental decline or preserve physical function in a recent trial, but the company said that setback will not affect the $1 billion manufacturing campus being built at the Newton/Walton county border.

Baxter’s Gammagard Liquid will be produced at the Covington plant and is already used to treat immune disorders, but in a small study of four Alzheimer’s patients presented in 2012, researchers said the drug could have promise in stemming the common neurodegenerative disease.

But a larger follow-up study of nearly 400 patients did not show the progress hinted at previously, as Gammagard did not significantly reduce decline over 18 months.

"Based on these results, Baxter will reconsider its current approach for its Alzheimer’s program and will determine next steps after full data analyses. The current Baxter studies of immunoglobulin in mild-to- moderate Alzheimer’s disease will be discontinued," a Baxter spokeswoman said in an email.

"Additional analyses from the study, including imaging, will be made available later this year as part of a full presentation of the Gammaglobulin Alzheimer’s Partnership study at the Alzheimer’s Association International Conference, July 13-18 in Boston."

The Covington plant will produce two drugs, Gammagard and albumin. Gammagard is a liquid blood therapy for patients with immune deficiencies and is created by taking antibodies from healthy people by filtering their donated blood plasma, according to Baxter. People who lack antibodies have trouble fighting off infections from bacteria and viruses.

The Covington plant was not dependent on the results of the Alzheimer’s study.

"The decision to build the new facility was based on the need for increased capacity across all of our plasma-based treatments globally, and the project was not dependent on the results of the Alzheimer’s studies. The Covington facility will continue to be a critical asset for our plasma business in the future," a spokesperson said by email.

In the latest study, there were sub-groups that did show progress, including moderate-stage Alzheimer’s patients and those who carry a specific genetic risk factor for Alzheimer’s, and Baxter will continue to look at the data in that area, said Ludwig Hantson, president of Baxter’s BioScience business, in a press release.

Baxter’s Covington plant will produce its products by collecting blood plasma from around the state through collection centers. The plasma then will undergo fractionation at the Covington plant, which "is the process of separating proteins out of source plasma, including albumin, immunoglobulins and clotting proteins.