What characteristic best describes partial agonists?

Partial agonists are substances that bind to receptors and activate them, but to a lesser degree than full agonists. This means that while they do initiate a response within the cell, their efficacy in stimulating the receptor is not complete—hence the term "partial." This characteristic allows them to modulate receptor activity in a way that can lead to different therapeutic effects compared to full agonists or antagonists.

In contrast to full agonists that produce a maximal response by completely stimulating the receptors, partial agonists create a submaximal response even when all available receptors are occupied. This property can be advantageous in certain clinical situations where it may be desirable to achieve a moderate level of receptor activity without the risk of overstimulation.

The other options do not accurately reflect the behavior of partial agonists. Full agonists are recognized for their ability to bind and fully stimulate receptors, antagonists block receptor activity without producing a response, and agents that increase receptor sensitivity without binding do not fit within the classification of agonists or antagonists. This distinction is crucial for understanding the pharmacodynamics of these compounds in anesthesia and pain management.