Bioavailability measures how much of a substance (drug, phytoactive compound, etc.) enters the circulation to reach the target cells and tissues. In simple terms, it refers to the fraction of an administered substance that reaches the bloodstream.
A Bioenhancer or Bioavailability enhancer is an agent that is combined with a substance (drug, phytoactive compound, etc.) to enhance the substance’s bioavailability and bioefficacy. Other than this, the agent itself does not have any therapeutic activity of its own.