I am not aware of a medication called Rhovane to treat chemical dependency.
However, there is a medication named ReVia (naltrexone).This medicine is a narcotic antagonist used to treat alcohol or narcotic addiction. It may also be used to treat other conditions as determined by your doctor.
I am sure of your concern but I would recommend that you attend Al-Anon or similar support groups for family members of alcoholics and the chemical dependents, so you may have a better understanding of his condition and also learn to cope the stress of living with a person with this type of illness.
I do not believe that it is available in the US. It is available in Canada and Mexico.
In researching this drug I have seen one reference to it being an antidote to cocaine, but unfortunately I cannot quote you the reference where I saw this.
I hope that this is of some us.
p.s. Immovane is another trade name for this drug.