(043) IS DAILY PDE5I SUPPLEMENTATION WITH TRIMIX ICI INJECTIONS BENEFICIAL IN POST-PROSTATE CANCER TREATMENT? AN EVALUATION OF EFFICACY AND SAFETY DATA

Abstract Introduction Trimix intracorporeal injections (ICI) are considered a dependable treatment option for men who have undergone radical prostatectomy, often resulting in satisfactory erections suitable for penetration. However, higher doses of Trimix ICI can cause penile pain and are linked to an increased incidence of priapism. Objective This study aimed to investigate whether daily use of Phosphodiesterase 5 Inhibitors (PDE5i) can enhance the effectiveness of ICI, enabling patients to achieve the desired response with lower Trimix ICI dosages. Methods We performed a retrospective analysis of our institutional database to identify patients experiencing erectile dysfunction following prostate cancer treatment. Data from 233 patients who underwent Ultrasound Penile Doppler (US PD), used Trimix ICI with or without daily PDE5i between 2020 and 2023, and had a follow-up period of at least one year were included. Correlation was drawn between the changes in Trimix dosage required to attain a satisfactory erection and the different variables including demographic data and ultrasound penile doppler readings. Patients were categorized into two groups according to their PDE5i usage: group 1 (no PDE5i intake, n = 128) and group 2 (PDE5i intake, n = 105). To assess the impact of PDE5i on changes in ICI dosage, a chi-squared test was utilized. Results In the overall patient cohort, 17.2% had diabetes, 51.9% had hypertension, 71.7% had undergone prostatectomy, 24.5% had a history of radiation treatment, 18.5% had received androgen deprivation therapy, and 15.9% reported using beta blockers. Additionally, 55.8% of the patients used vacuum erection devices. One observation found, most of the patients who took daily PDE5i were from the non-radiation therapy group. (P = 0.03) The correlation between changes in intracorporeal injection dosage and various parameters is detailed in Table 1. Most parameters were not statistically significant, with the exceptions of patient age (P = 0.01) and the initial prescribed Trimix injection dose, which was determined based on the patient's response to initial ICI given during penile Doppler ultrasound. A significantly higher proportion of patients in group 1 reported an increase in Trimix ICI dosage during follow-up compared to group 2 (78.4% vs. 61.9%, p = 0.01). Importantly, no cases of priapism were observed among the 233 patients throughout the follow-up period. Conclusions Although additional comprehensive follow-up is warranted, these preliminary findings suggest that regular daily administration of PDE5 inhibitors is both safe and may effectively reduce the necessity for escalating Trimix ICI dosages in this particular patient cohort. Disclosure No.