Final answer:
The antidepressant that can function as an antipruritic agent and treat gastric ulcers through histamine blockade is amitriptyline, a tricyclic antidepressant also used for various other conditions such as anxiety and insomnia.
Step-by-step explanation:
The antidepressant that can be used as an antipruritic agent and for the treatment of gastric ulcers due to its potent histamine blockade is amitriptyline. Amitriptyline is a tricyclic antidepressant that has antihistaminic properties which can block H1 and H2 receptors. These properties make it suitable not only for its primary use in treating depression but also for providing relief from itching (antipruritic) and reducing stomach acid production in gastric ulcers.
Amitriptyline's ability to attenuate the activity of the hypothalamic-pituitary-adrenocortical system and its effects on neurotransmitter reuptake facilitate a broad range of therapeutic effects. This includes potential use in the treatment of anxiety and insomnia, conditions sometimes associated with depressive states. Despite these benefits, caution is advised due to potential side effects and interactions with other medications.