On Sun, 10 Feb 2019 13:37:55 +1100, "Rod Speed"
wrote:

There are drugs that have been out there for decades and they
make some insignificant change that allows a whole new patent
to be issued without giving up the right to the old one.

But other drug companys are free to do that with your original drug too.

I don't know about OZ but in the US, the original
drug's patent gets extended, it isn't a new patent.

You were there one the claimed a whole new patent.

The drop dead date looks like a new patent but it is really just an
extension on the old one. The original drug is still protected.