William is a 62-year-old male who is requesting a prescription for sildenafil (Viagra). He should be screened for ______ before receiving a prescription for sildenafil.

Erectile dysfunction is commonly treated with phosphodiesterase-5 (PDE-5) inhibitors such as Sildenafil (Viagra), which work by enhancing nitric oxide–mediated vasodilation in the corpus cavernosum to improve penile blood flow. Because these medications also cause systemic vasodilation, they can significantly lower blood pressure. Careful screening for contraindications is essential before prescribing to prevent life-threatening hypotension. Patient safety depends on identifying high-risk drug interactions and cardiovascular risks. Rationale: A. Androgen use is not a contraindication to Sildenafil (Viagra) therapy. Although testosterone levels may influence libido and erectile function, concurrent androgen therapy does not create a dangerous pharmacologic interaction with PDE-5 inhibitors. Screening for androgen use may be clinically relevant in evaluating erectile dysfunction causes, but it is not a safety exclusion criterion. B. Prostate cancer is not an absolute contraindication to sildenafil use. Patients with prostate cancer may experience erectile dysfunction due to surgery, radiation, or hormonal therapy, and PDE-5 inhibitors are often used to manage this condition. However, sildenafil does not treat cancer itself and should be used cautiously based on overall health status, not as a strict contraindication. C. Renal dysfunction may require dose adjustment of Sildenafil (Viagra) due to altered drug clearance, but it is not an absolute contraindication. Patients with mild to moderate renal impairment can still safely use the medication with appropriate dosing modifications. Screening is important, but the primary life-threatening concern is not renal impairment alone. D. Nitrate use is an absolute contraindication because combining nitrates with Sildenafil (Viagra) can cause severe and potentially fatal hypotension. Both drugs increase nitric oxide-mediated vasodilation, leading to a synergistic drop in blood pressure. This interaction can result in syncope, myocardial ischemia, or cardiovascular collapse, making it the most critical screening factor before prescribing sildenafil.