Phyllanthus niruri (chanca piedra) and phylanthus amarus are in fact two different species. Chanca piedra is more used for kidney stones.
All of the information on the net is wrong about amarus and niruri, they group them indiscriminantly together as the same plant - error.
Amarus is what you want for the liver, it can eradicate certain forms of hep virus, and it will break stones in the liver and it will strengthen the liver system. It has similar but not as strong properties as guduchi (heartleaf moonseed - much better herb than milk thistle btw).