Which pharmacokinetic property is associated with barbiturates?

Barbiturates are known to induce hepatic microsomal enzymes, which leads to an increased metabolism of various drugs, including oral contraceptives. This induction can potentially decrease the effectiveness of oral contraceptives, resulting in unintended pregnancies. The mechanism behind this involves barbiturates enhancing the activity of cytochrome P450 enzymes in the liver, which are responsible for the metabolism of many substances. Therefore, understanding this interaction is crucial in clinical settings, especially for patients taking oral contraceptive medications while being prescribed barbiturates.

The other options do not accurately describe the characteristics of barbiturates. For example, barbiturates are not substrates of lipase; instead, they are primarily metabolized in the liver. Additionally, they do not act as competitive antagonists in the liver; rather, they can enhance the effects of certain neurotransmitters like GABA. Lastly, barbiturates actually increase GABA receptor sensitivity rather than decrease it, leading to their sedative and anxiolytic effects.