Immacula Eugène worked at the CHSLD St-Lambert-Sur-le-Golf, a private-public long-term care facility for seniors in St-Lambert.
The 342 days Eugène has already served in jail will count toward the 15 month sentence.
She was arrested along with Marie-Margaret Pétimé in December 2013 on charges of administering a noxious substance, drug trafficking and conspiracy. Eugène was also charged in connection with an armed assault involving a pillow.
Last February, she pleaded guilty to five of the six charges against her, including assault and administering a noxious substance to two people without their knowledge or consent.
Eugène hid the drugs, which she stole from another institution, in the seniors' applesauce.
A coroner's inquest into the death of one of the residents, 87-year-old Denise Beaulieu, showed her consumption of the noxious substance in question, Serax, likely contributed to the sudden deterioration of her health.