Yes. Clinically it works as usual. Unfortunately not a lot of controlled data. NIH also uninterested in funding this research and Alkermes is not doing well financially, so this issue while important won't have a lot of answers on the offing any time soon.
W.r.t. to cirrhotic patients, are you trying to do alcohol or opioids? For opioids, these types of patients likely also have Hep C and other complicating issues, so often Vivitrol is not a good first line candidate medication. For alcohol, if you are cirrhotic you should probably be on something stronger (i.e. antabuse). It's not a one-line answer.