Naltrexone only removes the "high" or euphoric effects of alcohol (and opiates). It does not help with withdrawal (the effects after the "drug", in this case alcohol, leaves the body and the body no longer has them) and it does not even removes the cravings (usually habit) for it. You should think again what is the purpose of getting it and if its for the cravings then, it will not work (unless we talking about placebo effect). If you do wish to continue then make sure your liver is ok and then make an appointment with a doctor so he/she can discuss it further. And make sure you can support it as it might be a few months to a long term commitment.