Hello, My Grandmother Has Recently Been Diagnosed With SIADH. She

Hello, my grandmother has recently been diagnosed with SIADH. She is experiencing a lot of confusion as well as tremors & other symptoms because of it. Her primary doesn't think there are any underlying li ying neurological issues. She also prescribed an antidepressant called Mirtazipine. Is that pill safe for someone with her condition? Can it exacerbate her condition?
Thank you so much!