What is the function of hydrocholorothiazide in these combinations?

Hydrochlorothiazide functions primarily as a diuretic, which means it helps the body eliminate excess sodium and water through urine. This action reduces blood volume, which ultimately lowers blood pressure, making hydrochlorothiazide effective in treating hypertension. In combination therapies, it often enhances the efficacy of other antihypertensive medications by helping to mitigate fluid retention that may occur as a side effect of those medications. Its diuretic properties are a key component in managing conditions such as heart failure and hypertension.

While it's true that hydrochlorothiazide contributes to antihypertensive effects, its classification as a diuretic is what distinctly describes its primary role in these combinations. Other options like anticoagulants and beta-blockers do not accurately reflect the function of hydrochlorothiazide.