drugs 'effective' in the treatment of a disease = drugs 'effective' in treating a disease = drugs 'effective' against a disease
The law becomes 'effective' [=the law takes effect; the law will start to be used] next year.
the 'effective date' of the law [=the day when the law starts to be used]
(..) and a share. He became morose and isolated, began to drink heavily. On September , , he was fired... effective in two weeks. The news was broken to him by Max Schumacher... who was the president of the News Division at UBS. The two old friends (..)1976 Network