"We looked at all of it and we didn't see any difference between Ampligen and placebo," he said, referring to the inactive substance.

The other volunteers in the study received an inactive substance, or placebo.

They may contain inactive substances like tap water or chalk, wrong ingredients, incorrect doses or contaminants.

The lower estimates, on the other hand, were based on studies in which some patients used an inactive substance and others used Rogaine.

Placebos are inactive substances used to compare results with active substances.

These trials compared hydrazine sulfate with a placebo (an inactive substance that looks like the treatment being tested).

It is oxidatively destroyed by the oxygen in the air and is transformed into an inactive substance under the influence of light.

In the one that received the inactive substance, it rose to 59.4 from 51.5 percent.

About half the group received Ampligen, the other half an inactive substance, or placebo.

The study was intended to compare the drug with vitamin E and, as a control, to an inactive substance.