Long Term Effectiveness and Safety of Intracavernosal Botulinum Toxin A as an Add-on Therapy to Phosphosdiesterase Type 5 Inhibitors or Prostaglandin E1 Injections for Erectile Dysfunction.

Background: Some evidence suggests that intracavernosal botulinum toxin A (BTX-A IC) injections administered in addition to phosphodiesterase type 5 inhibitors (PDE5-Is) or prostaglandin E1 intracavernosal injections (PGE1 ICI) could effectively treat erectile dysfunction (ED) in non-responders, or insufficient responders to these pharmacologic treatments.

Aim: To determine the long-term effectiveness and safety of combined treatment involving a single injection of BTX-A IC as an add on therapy to PDE5-Is or PGE1-ICI for the treatment of ED of different etiologies.

Methods: A retrospective, uncontrolled, single center study was conducted. Data from 123 consecutive patients with ED who were insufficient responders to PDE5-Is or PGE1-ICI and who received onabotulinumtoxinA 100 U, abobotulinumtoxinA 250 U or 500 U IC as an add on to their current pharmacologic treatment were analyzed. All analyses were exploratory. Qualitative data were compared using the Fisher's exact test. Univariate and multivariate analysis were performed using logistic regression with Odds Ratios (OR). Only variables with P < .05 in the univariate analysis were selected for multivariate analysis.

Results: The minimally clinically important difference (relative to baseline severity of ED) in the International Index of Erectile Function-Erectile function domain (IIEF-EF) score was achieved in 50% of patients at 34 (27-42) days and in 41% at 5.9 (3.9 - 8.1) months following BTX-A IC in combination with PDE5-Is or PGE1 ICI. The severity of ED influenced response to BTX-A IC according to the multivariate analysis (OR = 0.3, IC(95%]) = (0.16 - 0.56). Neither being post prostatectomy nor the type of BTX-A affected the response. Effectiveness tended to decrease more over time with abobotulinumtoxinA 250 U than 500 U. The only side-effects were mild penile pain on injection (n = 1) and mild penile pain for 3 days following injection (n = 1); no systemic effects were reported.

Clinical Implications: BTX-A IC (all types) administered as an add on to registered pharmacologic treatments improved erectile function for at least 6 months in 41% of patients with ED of varying etiologies, and was safe.

Strengths & Limitations: A relatively large cohort of patients with ED was included, with a long follow-up period, however the study was retrospective, and uncontrolled.

Conclusion: This study provides preliminary evidence that BTX-A IC administered as an add-on therapy for ED that is insufficiently responsive to standard therapy is effective for at least 6 months, and is safe. Randomized clinical trials are now needed to fully confirm these results. Giuliano F, Joussain C, Denys P, Long Term Effectiveness and Safety of Intracavernosal Botulinum Toxin A as an Add-on Therapy to Phosphosdiesterase Type 5 Inhibitors or Prostaglandin E1 Injections for Erectile Dysfunction. J Sex Med 2022;19:83-89.