Background: Tadalafil is a PDE-5 (phosphodiesterase inhibitor) inhibitor that supports endogenous nitric oxide's vasodilatory actions and aids in erection maintenance. The penile duplex has proven to be very useful for imaging superficial structures and for determining the reasons of erectile dysfunction (ED).
Objectives: To assess the effect of daily oral tadalafil 5mg for 3 months on penile duplex parameters in erectile dysfunction patients.
Patients and Methods: A case control study involved 30 Egyptian patients ED. Appropriate clinical history and penile duplex examination before and after treatment with daily oral tadalafil mg for 3 months were performed.
Results: The mean age of the patients was 53.17 ± 7.8 years. We founded that  there was significant (p < 0.001) improvement in the level of erection after treatment. The rate of erection E1 and E2 was decreased from 53.3% to 3.3%. Likewise, the rate of E3-E5 was increased from 46.7% to 96.7%. Moreover, the mean duration of erection was elongated from 24.7 ± 5.3 to become 37.4 ± 3.8 and this was statistically significant (p < 0.001). Also, the mean peak systolic volume (PSV) was significantly (p = 0.001) increased after treatment (38.4 ± 9.1 cm/s) compared with the pre-treatment levels (23.9 ± 6.1 cm/s). Unlikely, the mean end diastolic volume (EDV) was insignificantly (p = 0.340) lower in post-treatment (2.25 ± 0.5 mL) compared with pre-treatment levels (2.97 ± 0.4 mL). Likely, the mean resistant index (RI) showed insignificant difference (p = 0.965) after treatment (0.9 ± 0.02) compared with before treatment (0.9 ± 0.08). For penile artery diameter, there was significant (p = 0.009) increase in the diameter after treatment (0.9 ± 0.1 mm) compared with before treatment (0.8 ± 0.1 mm).
Conclusion: Oral daily tadalafil 5mg for 3 months is considered an effective treatment for ED according to penile duplex parameters.