WHO ebola experimental drugs- Is it ethical?

The WHO has okayed the usage of the experimental Ebola drug zmap,
which in itself is fraught with a lot of ethical questions. According
to the WHO, the drug's benefits and side effects will have to be
explained to the patients before the drug can be administered to them.
However, this will raise a lot of ethical questions, not least if the
ebola patients are not infact being used as guinea pigs.