Having accepted the fact 

The condition is rare 

The prognosis terminal

The treatment nonexistent

A life ring rides the torrent

Of their thoughts of shortened lives

A potion fresh from the lab

In need of proof to test its power

The trial a mediaeval sort

Three doors one to open

Each contains a remedy

One is the potion full

One is  half the same elixir 

To determine its efficacy

At the lower extremity 

Of safe but subdued dose 

One is nothing a placebo

A false friend masquerading

As beneficial but of no value

Save to prove the others worth

Fate determines the choice

I determine the participants 

They accept the odds

For life or death at a toss