Pain associated with prostaglandin E₁-containing intracavernosal injection medication is associated with poor erectile function recovery after radical prostatectomy

Background: Intracavernosal injection therapy is often used as second-line therapy for erectile dysfunction associated with radical prostatectomy when therapy with phosphodiesterase-5 inhibitors has failed, but prostaglandin E1-containing vasoactive agents are associated with penile pain in some men.

Objectives: To define the incidence of pain with prostaglandin E1-containing intracavernosal injection mixtures for erectile dysfunction associated with radical prostatectomy when therapy with phosphodiesterase-5 inhibitors has failed, and whether pain was a predictor of erectile function recovery.

Materials and methods: Men who underwent radical prostatectomy and were commenced on intracavernosal injection within 12 months of radical prostatectomy were included. A pain visual analog scale (0-10) was used to assess the degree of pain. Erectile function recovery was defined as the International Index of Erectile Function domain score ≥24 using phosphodiesterase-5 inhibitors at 24 months.

Results: The study included 566 patients, mean age was 58 ± 14 (42-74) years. Duration post-radical prostatectomy at intracavernosal injection training was 3.5 ± 3.5 m. Nerve sparing status: bilateral 76%, unilateral 13%, and non-nerve sparing 11%. Incidence of pain with intracavernosal injection per nerve sparing status: bilateral 10% of patients, unilateral 32%, non-nerve sparing 92% (p < 0.001). Median visual analog scale in those experiencing pain: bilateral 4 (interquartile range 3, 5), unilateral 5.5 (interquartile range 3, 6), non-nerve sparing 7 (interquartile range 3, 9) (p < 0.001). Phosphodiesterase-5 inhibitors success at 24 months (no pain vs. pain): bilateral 70% vs. 40% (p < 0.001), unilateral 50% vs. 28% (p < 0.001), non-nerve sparing 10% vs. 0% (p < 0.001). On multivariate analysis, predictors of failure to respond to phosphodiesterase-5 inhibitors at 24 months post-radical prostatectomy included baseline erectile function, increasing age, incomplete nerve-sparing surgery, and presence of pain.

Discussion: The presence of penile pain with intracavernosal injection is associated with poorer erectile function recovery post-radical prostatectomy.

Conclusions: Incidence of pain is high in men with non-nerve sparing radical prostatectomy; older patient age, poorer nerve sparing, poor baseline erectile function, and the presence of penile pain with prostaglandin E1-containing intracavernosal injection medication, were predictive of poor erectile function recovery using phosphodiesterase-5 inhibitors at 24 months.