Which antihistamine is administered intravenously (V) when a blood transfusion reaction causes pruritus?

A. A client with benign prostatic hyperplasia: Terazosin is an alpha-1 adrenergic blocker that relaxes smooth muscle in the prostate and bladder neck, improving urine flow and reducing symptoms of BPH such as urinary hesitancy and incomplete bladder emptying.

B. A client with a history of syncope: Terazosin can cause orthostatic hypotension, especially with the first dose, increasing the risk of dizziness and fainting. Administering it to a client prone to syncope could exacerbate this risk.

C. A client with fluid volume deficit: Hypovolemia can intensify the blood pressure–lowering effects of terazosin, increasing the likelihood of symptomatic hypotension and falls. Careful assessment and correction of fluid status are necessary before administration.

D. A client with hypotension: Terazosin lowers blood pressure by vasodilation. Administering it to a client who already has hypotension could cause severe hypotensive episodes, dizziness, or shock.

A. Fexofenadine: Fexofenadine is a second-generation antihistamine typically administered orally. It is non-sedating and not available in an intravenous form, so it is not suitable for immediate treatment of pruritus during an acute blood transfusion reaction.

B. Loratadine: Loratadine is also a second-generation oral antihistamine. It does not have an intravenous formulation and its onset is slower, making it ineffective for rapid symptom relief in acute transfusion reactions.

C. Cetirizine: Cetirizine is a second-generation antihistamine available orally. Although it is effective for allergic reactions, it does not have an IV form for rapid intervention during a transfusion-related pruritus episode.

D. Diphenhydramine: Diphenhydramine is a first-generation antihistamine that can be administered intravenously for rapid relief of pruritus during acute allergic reactions, including blood transfusion reactions. Its IV form allows immediate onset of action, which is critical in managing these acute symptoms.