The goal of this clinical trial is to evaluate whether daily dosing with tadalafil 5 mg combined with on-demand sildenafil 100 mg can improve erectile function in men with erectile dysfunction (ED) who do not respond to PDE5 inhibitor alone.
The main questions it aims to answer are:
* Does the combination of daily tadalafil and on-demand sildenafil lead to a greater improvement in erectile function (measured by the IIEF-EF domain) compared with on-demand sildenafil alone?
* Is the combination therapy safe and well tolerated in this patient population?
Researchers will compare:
* Group A: Daily tadalafil 5 mg plus on-demand sildenafil 100 mg
* Group B: Daily placebo plus on-demand sildenafil 100 mg
to determine whether the combination regimen provides superior improvement in erectile function and patient satisfaction.
Participants will:
* Undergo baseline assessment including medical history, physical examination, and laboratory tests.
* Be randomly assigned to one of the two treatment groups.
* Take the assigned medications for 12 weeks.
* Complete follow-up evaluations at 4, 8, and 12 weeks, including:
International Index of Erectile Function (IIEF-15) questionnaire Erection Hardness Score (EHS) assessment Reporting of any adverse effects