Taking pentoxifylline in combination with sildenafil does not appear to improve erectile dysfunction (ED) symptoms, according to new research in Sexual Medicine.
Pentoxifylline is a “nonspecific” phosphodiesterase type 5 (PDE5) inhibitor used to treat occlusive arterial disease, a condition that narrows blood vessels and impairs blood flow. Because ED can be linked to poor blood flow to the penis, researchers investigated whether adding pentoxifylline to ED therapy could be worthwhile.
The study involved 58 men with ED in Singapore. The men’s average age was 60 years, and they had been taking 100 mg of sildenafil (another PDE5 inhibitor) on demand for the previous three months with “suboptimal” results.
The men were randomly assigned to take 400 mg of pentoxifylline three times a day or a placebo. All of the men continued to take sildenafil on demand, as needed, for erectile function.
The study lasted for eight weeks. At baseline and again at the close of the study, the men completed the 5-item and 15-item International Index of Erectile Function assessments (IIEF-5 and IIEF-15).
“By using both the IIEF-5 and the IIEF-15, we aim to not only to assess the effects of pentoxifylline on [erectile function], but also its possible effects on other aspects of sexual function,” the authors explained.
Before treatment, the average IIEF-5 scores for the pentoxifylline and placebo groups were 12.8 and 13.1, respectively. After eight weeks, the scores rose to 14.11 for the pentoxifylline group and 14.87 for the placebo group. (IIEF scores range from 1 to 25, with higher scores indicating better erectile function.)
However, there were improvements in the overall satisfaction domain of the IIEF.
“This significant improvement in [overall satisfaction] but not in other domains may suggest other possible aspects of sexual function not clearly evaluated in the IIEF and, thus suggesting pentoxifylline improves [an] aspect of ED not fully evaluated by the IIEF,” the authors explained.
Some patients experienced gastrointestinal, neurological, musculoskeletal, and dermatological side effects. Four participants withdrew from the study as a result. There were no significant differences between the two groups in terms of side effects.
The authors noted that 33% of the participants were noncompliant with treatment, meaning they did not take 30 or more of the 168 caplets they were given. It’s possible that the frequent dosing (three times a day) played a role in noncompliance.
“Our trial suggests that the use of combination therapy does not improve the management of patients compared to monotherapy,” the researchers concluded.
Law, Yu Xi Terence, BSc (Hons.), MBBS, MRCS, et al.
“A Small Group Randomized Double-Blind Placebo-Controlled Study to Evaluate the Efficacy of Daily Pentoxifylline in the Management of Patients With Erectile Dysfunction with Suboptimal Treatment Response to Sildenafil.”
(Full-text. Published online: October 1, 2019)