During a routine checkup, a patient states that she is unable to take the prescribed antihistamine because of one of its most common adverse effects. The nurse suspects that which adverse effect has been bothering this patient?

Choice A reason: Consuming a high-fat meal does not increase the medication absorption, but rather delays it. A high-fat meal can reduce the peak plasma concentration and prolong the onset of action of sildenafil.

Choice B reason: Taking the medication 2 hours prior to sexual activity is not the optimal timing, as sildenafil has a half-life of about 4 hours and reaches its peak effect within 30 to 120 minutes. The recommended dose is 50 mg taken as needed, approximately 1 hour before sexual activity.

Choice C reason: Swallowing the medication with grapefruit juice does not improve the action, but rather inhibits it. Grapefruit juice can interfere with the metabolism of sildenafil and increase its plasma concentration and side effects.

Choice D reason: Avoiding ingestion of the medication with nitrates is the correct information, as it can cause a severe and potentially fatal drop in blood pressure. Nitrates are drugs used to treat angina and heart failure, and they can interact with sildenafil to cause vasodilation and hypotension.

Choice A reason: This is incorrect because withholding all medications may cause hyperglycemia or ketoacidosis in the patient, especially if they are taking insulin or sulfonylureas. The nurse should consult with the prescriber to adjust the dose or timing of the medications according to the patient's blood glucose level and the duration of the procedure.

Choice B reason: This is correct because contacting the prescriber to clarify orders is the best action by the nurse, as the prescriber can provide specific instructions on how to manage the patient's oral antidiabetic drugs before and after the oral endoscopy. The nurse should also monitor the patient's blood glucose level closely and report any abnormal findings to the prescriber.

Choice C reason: This is incorrect because administering half the original dose may not be appropriate for the patient, as it may cause hypoglycemia or hyperglycemia depending on the type and dose of the medication and the patient's blood glucose level. The nurse should not make any changes to the medication regimen without the prescriber's approval.

Choice D reason: This is incorrect because giving the medication with a sip of water may violate the NPO status of the patient, which is necessary to prevent aspiration or interference with the oral endoscopy. The nurse should not administer any oral medications or fluids to the patient unless the prescriber allows it.