A 60-year-old man comes to the office due to erectile dysfunction that has progressed slowly over the last year. He finds it difficult to attain an erection and has noted a decrease in nocturnal erections. Medical history is significant for type 2 diabetes mellitus and benign prostatic hyperplasia. Ophthalmologic evaluation 6 months ago revealed diabetic retinopathy that was treated with photocoagulation. The patient also had a negative treadmill cardiac stress test 4 months ago after presenting with atypical chest discomfort. Current medications include metformin, sitagliptin, rosuvastatin, and doxazosin. Blood pressure is 122/70 mm Hg and pulse is 76/min. Cardiopulmonary examination is unremarkable except for mildly decreased pedal pulses on the right. There is decreased vibration sensation in both feet. Hemoglobin A1c measured 2 weeks ago was 8%. The patient requests a prescription for sildenafil. Which of the following is the most important concern in prescribing sildenafil to this patient?

Question

A 60-year-old man comes to the office due to erectile dysfunction that has progressed slowly over the last year.  He finds it difficult to attain an erection and has noted a decrease in nocturnal erections.  Medical history is significant for type 2 diabetes mellitus and benign prostatic hyperplasia.  Ophthalmologic evaluation 6 months ago revealed diabetic retinopathy that was treated with photocoagulation.  The patient also had a negative treadmill cardiac stress test 4 months ago after presenting with atypical chest discomfort.  Current medications include metformin, sitagliptin, rosuvastatin, and doxazosin.  Blood pressure is 122/70 mm Hg and pulse is 76/min.  Cardiopulmonary examination is unremarkable except for mildly decreased pedal pulses on the right.  There is decreased vibration sensation in both feet.  Hemoglobin A1c measured 2 weeks ago was 8%.  The patient requests a prescription for sildenafil.  Which of the following is the most important concern in prescribing sildenafil to this patient?

Quizplus · Accepted Answer

11ec25c8_d28e_2383_bc81_d31643681ba9_MD0003_00 Patients with diabetes have a high risk for erectile dysfunction (ED), and the risk increases with age and duration of diabetes. Contributing factors include arterial disease, autonomic neuropathy, and multiple potential comorbid conditions and concurrent medications. First-line treatment for most patients with ED consists of phosphodiesterase-5 (PDE-5) inhibitors (eg, sildenafil), which have vasodilatory effects. However, PDE-5 inhibitors should be used with caution due to risk of adverse effects and drug interactions. In this patient, giving sildenafil along with an alpha blocker (doxazosin) can lead to severe hypotension. To reduce this risk, patients should be prescribed the lowest effective doses of both medications, with careful dose titration. In addition, these 2 drug classes should be taken at least 4 hours apart to minimize the interaction. Like with alpha blockers, PDE-5 inhibitors can interact with nitrates to cause severe hypotension. Antihypertensives generally should be used with caution with PDE-5 inhibitors. (Choice A) Diabetic retinopathy is not a contraindication to PDE-5 inhibitor use. PDE-5 inhibitors can cause a temporary bluish visual discoloration due to cross-reactivity with phosphodiesterase-6 inhibitors involved in color vision in the retina. Nonarteritic ischemic optic neuropathy (NAION) has been noted with PDE-5 inhibitor use, but it is unclear whether this reflects a causal relationship or shared underlying risk factors between NAION and ED (eg, age, hypertension, diabetes). (Choice C) There is no significant interaction between PDE-5 inhibitors and metformin. (Choices D and E) Peripheral neuropathy and peripheral artery disease are not contraindications to PDE-5 use, and some studies have found that PDE-5 inhibitors may actually decrease symptoms in diabetic peripheral neuropathy and peripheral artery disease. Educational objective: First-line treatment for erectile dysfunction in diabetic patients consists of phosphodiesterase-5 inhibitors (eg, sildenafil). However, these medications can cause hypotension, especially in patients who are taking alpha blockers or nitrates. References: Phosphodiesterase-5 inhibitors for erectile dysfunction in patients with diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials. (http://www.ncbi.nlm.nih.gov/pubmed/26180759)

A 60-Year-Old Man Comes to the Office Due to Erectile