Centrally acting adrenergic blockers are indicated in hypertensive patients when:

A) they are not taking diuretics
B) they are between 21 and 65 years old
C) they are older than 65 years old
D) they have not responded to other hypertensive therapies

D) they have not responded to other hypertensive therapies
Centrally acting adrenergic blockers are not regarded as first-line therapies in hypertension. These drugs tend to be used in cases in which the affected person has not responded to other therapies.