A patient asks the nurse to tell her more about a new drug the patient has been prescribed called ranolazine (Ranexa). Which response by the nurse is accurate?

Choice A rationale

Alpha blockers primarily exert their effects on the vascular smooth muscle by blocking alpha-1 adrenergic receptors. This action leads to vasodilation, which lowers blood pressure. They do not have a direct mechanism of action that would precipitate acute renal failure upon first dose administration. Renal function, while monitored, is not the most immediate or common adverse effect to assess for.

Choice B rationale

Alpha-1 adrenergic receptors, when blocked by alpha blockers, cause vasodilation of both arteries and veins. This leads to a decrease in peripheral vascular resistance and venous return, causing a significant drop in blood pressure. This effect, known as orthostatic hypotension or "first-dose phenomenon," is a common and critical adverse effect to assess for, as it can cause dizziness and fainting.

Choice C rationale

Blood dyscrasias, or disorders involving the cellular components of blood, are not a typical or immediate adverse effect associated with the first administration of an alpha blocker. While some medications can cause these rare side effects over long-term use, the acute and most common concern with the initial dose is related to its cardiovascular effects on blood pressure.

Choice D rationale

While alpha blockers can indirectly affect the heart rate through baroreceptor reflexes in response to hypotension, they are not typically associated with the direct induction of significant dysrhythmias as a primary adverse effect upon first administration. The immediate and most profound hemodynamic effect is the peripheral vasodilation and subsequent hypotension, which takes precedence in initial assessment.

Choice A rationale

Radioactive iodine (RAI) therapy involves the administration of a radioactive isotope of iodine, I-131, which is selectively taken up by the thyroid gland to destroy overactive thyroid cells. Since the patient's body contains radioactive material, they must follow strict precautions to prevent radiation exposure to others. This includes avoiding close contact with pregnant women and young children for several days to weeks, as they are more susceptible to the harmful effects of radiation.

Choice B rationale

This is incorrect. Patients are generally advised to stop taking antithyroid medications, such as methimazole or propylthiouracil, several days before RAI therapy. These drugs prevent the thyroid gland from utilizing iodine, which would interfere with the uptake of the radioactive iodine, rendering the treatment ineffective. The goal is to maximize the absorption of the radioactive iodine by the thyroid gland.

Choice C rationale

This is incorrect. A patient preparing for radioactive iodine therapy must follow a low-iodine diet for one to two weeks before the treatment. High-iodine foods would saturate the thyroid gland with non-radioactive iodine, competing with the radioactive iodine for uptake and significantly reducing the efficacy of the therapy. Limiting iodine intake ensures the thyroid is "hungry" for the radioactive isotope.

Choice D rationale

While increasing fluid intake is generally a healthy practice, it is not a primary safety instruction for radioactive iodine therapy. The main instruction is to drink fluids and urinate frequently after the procedure. This helps to flush any unabsorbed radioactive iodine from the body more quickly, reducing radiation exposure to other parts of the body, particularly the bladder.