Oral Tadalafil Administration Plus Low Dose Vasodilator Injection: A Novel Approach to Erection Induction for Penile Color Duplex Ultrasound

Abstract

We prospectively compared clinical response and penile color duplex ultrasound results of oral tadalafil 20 mg plus low dose intracavernous injection of vasoactive agents with those of intracavernous injection and oral tadalafil 20 mg alone. We also observed the best approach to facilitate penile color duplex ultrasound and that most preferred by patients. All 56 patients with erectile dysfunction underwent penile color duplex ultrasound 3 times at an interval of at least 1 week using different pharmacological induction methods, including tadalafil mode (20 mg tadalafil), intracavernous injection mode (30 to 60 mg papaverine) and mixed mode (15 mg papaverine plus 20 mg tadalafil). Ultrasound parameters included peak systolic and end diastolic velocity, resistance index and acceleration time. Clinical response was assessed by the erection hardness score. Patient preference was determined when all tests were finished. For penile color duplex ultrasound parameters no significant difference was observed between intracavernous injection and mixed modes. However, for tadalafil mode peak systolic velocity of the 2 cavernous arteries measured 15 minutes after induction were significantly lower than for intracavernous injection and mixed modes. Also, acceleration time of the right cavernous artery measured 5 minutes after induction and left cavernous artery measured 15 minutes after induction in tadalafil mode were significantly shorter than those in intracavernous injection and mixed modes. No severe side effect occurred in tadalafil and mixed modes but 2 patients experienced priapism in intracavernous injection mode. Of the patients 55.4% preferred tadalafil mode, an incidence significantly higher than intracavernous injection (16.1%) and mixed (28.5%) modes. Oral tadalafil plus low dose vasodilator led to a significantly better clinical response than high dose vasodilator. Penile color duplex ultrasound parameters showed no difference between the 2 modes. Thus, this mixed mode emerges as a possible alternative to high dose vasodilator injection.