A 55-year-old male with a history of diabetes mellitus and hypertension presents with erectile dysfunction (ED). He has tried phosphodiesterase type 5 (PDE5) inhibitors (e.g., sildenafil) but experienced minimal improvement. His physician considers alternative treatment options, including intracavernosal injections. Which of the following prostaglandins is most commonly used in intracavernosal injections for the treatment of erectile dysfunction?
