Does Naltrexone cure alcoholism or opiate addiction?

No.  Alcoholism and drug addiction is a chronic, complex, and multi-factorial, life-long disease.  There is no known cure.  It should be considered a chronic brain disease.  Alcoholism, as with most addictions, is a result of psychosocial and physiological malfunctions.  BOTH the physical aspect and the psychosocial/ behavioral/emotional aspects of this disease should be addressed to have the highest chance of obtaining and maintaining, sobriety.