I saw a film back in the early 80's i think.
A guy keeps going back in time to collect a drug which the people in the future use.
He injects a drug into people and when they are high he punches a spike into their head to collect there brain fluid, and this is the drug they use in the future.
I have a vague idea Rutger Hauer was in it, but not too sure.
Any ideas?
John