Well, its an approved drug, so they are using 505(2)(b). We don't have any visibility on how far along they are into the clinic with perfecting the formulation and animal testing, etc., so it's impossible to say when they might be ready to file an IND application.
Once in clinical trials, I assume they will go for a Phase 1/2 combined study. I don't know anything about Vivitrol...are their multiple dosages? The scope of the Phase 1/2 will depend on how many dosages are being tested (e.g., ropinirole is taking longer because four separate dosages are being tested).
If the Phase 1/2 is successful, I assume it will be outlicensed at that point.
If not, need at least one Phase III efficacy and one Phase III safety study.
If they are fast, they could get it done in three years or less.