The following approach has not been proved effective but may be used: If hepatotoxicity is possible (if aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels are normal and acetaminophen level is initially elevated), N - acetylcysteine is given 140 mg / kg orally loading dose and 70 mg / kg orally every 4 hours for the first 24 hours.