The Efficacy of Combination Treatment with Injectable Testosterone Undecanoate and Daily Tadalafil for Erectile Dysfunction with Testosterone Deficiency Syndrome

Abstract

Both testosterone therapy and chronic treatment with phosphodiesterase type 5 inhibitors (PDE5Is) have positive effects on the histology of penile corpora and erectile function. However, few clinical studies have evaluated the efficacy of combination therapy with both testosterone replacement and chronic PDE5Is. This study was designed to evaluate the efficacy and safety of combination treatment with long-acting injectable testosterone undecanoate (TU) and a once-daily tadalafil 5 mg for erectile dysfunction with testosterone deficiency syndrome. Sixty patients were consecutively enrolled and followed for 36 weeks. Thirty patients were randomly assigned to group I and received 1,000 mg of parenteral TU on day 1, followed by additional injections at weeks 6 and 18 with on-demand tadalafil 10-20 mg during the 30 weeks of treatment. The remaining 30 patients received the same dose and schedule of TU as group I, and were prescribed once-daily tadalafil 5 mg during 30 weeks. Serological tests were performed, and the International Index of Erectile Function (IIEF), Aging Males' Symptoms (AMS) questionnaires, and Global Assessment Question (GAQ) were administered to the patients. Total IIEF and AMS scores were significantly improved during the 30 weeks of treatment in both groups. When IIEF scores were compared between the two groups, group II showed better symptom scores than group I at weeks 6 and 30. A similar pattern was observed when comparing AMS scores between the groups. At week 36, changes in IIEF and AMS scores that indicated worsened symptoms compared with week 30 were observed in both groups; group II showed better symptom scores than group I. On the GAQ, the ratio of patients reporting improvement in erectile function was significantly higher in group II than group I. The combination of long-acting injectable TU and once-daily tadalafil 5 mg produced a significant improvement in erectile function. Moreover, the improvement in erectile function was well maintained, even after the cessation of treatment.