Renal and Urinary System 1 out of 241
A 70-year-old man comes to the physician for a follow-up evaluation. Eight months ago, he presented with a 6-month history of increased urinary frequency, difficulty to initiate urination, and straining to maintain the urinary stream. Digital rectal examination showed a symmetrically enlarged, nontender prostate with a rubbery texture. Laboratory studies showed a prostate-specific antigen level of 2.1 ng/mL. Abdominal ultrasound showed a post-void residual urine volume of 250 mL and bladder wall thickening. The patient received appropriate treatment. His vital signs are within normal limits. Laboratory studies today show a PSA level of 0.9 ng/mL. Which of the following medications was most likely used to treat this patient?
Dutasteride
Five-alpha-reductase inhibitors (5-ARIs) like dutasteride are indicated in patients with BPH who present with evidence of prostate enlargement (> 30 mL on imaging), a palpable prostate enlargement on DRE, and/or PSA > 1.5 ng/dL. These agents prevent the conversion of testosterone to dihydrotestosterone, decreasing the size of the prostate and providing symptomatic relief as well as reducing the risk of acute urinary retention and the need for prostatic surgery. Patients usually experience symptomatic relief and a reduction in serum PSA (∼ 50% decrease) after 6 months of using 5-ARIs.
PSA levels must be interpreted with the proper correction factor when screening for prostate cancer in patients who have been treated with 5-ARIs because of the associated PSA level decrease. Oxybutynin
Antimuscarinic agents such as oxybutynin are used to treat the irritative symptoms of BPH (e.g., urinary urgency and urinary frequency), which are due to detrusor overactivity. By blocking the muscarinic receptors, these agents cause relaxation of the detrusor muscle within the bladder and increase the risk of urinary retention, which explains why they are contraindicated in patients with significant PRV, as seen here. Regardless, antimuscarinic agents have no effect on prostate growth and thus PSA levels. FlutamideThe antiandrogen drug flutamide is primarily a component of androgen deprivation therapy for advanced prostate cancer. It is associated with a high risk of toxicity and adverse effects and is not routinely used in the management of BPH. Terazosin
Alpha-blockers such as terazosin are the first-line pharmacotherapy in symptomatic patients with moderate to severe BPH. These agents are smooth muscle relaxants that decrease the resistance to urinary outflow by causing smooth muscle relaxation in the bladder neck and the urethra, thereby improving symptoms in patients with BPH. However, alpha-blockers have little to no effect on prostate growth and thus PSA levels. Tadalafil
Phosphodiesterase type 5 (PDE5) inhibitors (e.g., tadalafil), which are primarily used for the treatment of erectile dysfunction, may also be used to treat mild/moderate BPH with or without erectile dysfunction. Evidence regarding the effectiveness of PDE5 inhibitors is, however, limited. Furthermore, this class of drugs does not have a direct effect on prostate growth and thus PSA levels.
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