How much milk thistle do you take and how often? And also where do you get it at?

I have been taking MT for ages.
A friend of mine, hepatologist ( MD works with transplants etc ) at the time confirmed milk thistle is one of the safest & best liver protectors.
Beware the herb must be standardized (= HPLC or else tested to insure a given % of active chemicals ).
Cheap yet standardized you may find everywhere.
I usually buy at BAC or puritan.com
Dosages range from 2 to 6 200mg caps/day.

I got some liverX and it says that there is 100mg of milk thistle in it in 1 caps. How much do u take when on a cycle?