A Tilton man is facing up to eight years in prison after admitting that he switched out a prescription medication meant for children. Prosecutors say 41-year-old Thomas Poirier was employed at Spaulding Academy and Family Services in Northfield when a co-worker realized Ritalin was missing from a controlled drug cart. Surveillance video showed Poirier removing the Ritalin from the cart over a period of a few days and replacing it with an unknown substance. As a result, two children who needed the pills suffered serious psychological and physical harm. Poirier pleaded guilty to multiple charges and will be sentenced at a later date.