[Standard doses of tadalafil for different ED patients]

To observe the effects of different doses of tadalafil on ED, and to search for appropriate doses for the treatment of different ED patients.

Based on the baseline peak systolic velocity (PSV) of cavernosal arteries, 136 ED patients were divided into Groups A (PSV > 15 cm/s), B (PSV > 15 cm/s), C (PSV < 15 cm/s) and D (PSV <15 cm/s) to receive oral tadalafil at 10 mg (Groups A and C) and 5 mg (Groups B and D) on alternate days for 4 weeks. All of them were scored on IIEF-5 and detected for PSVs of the bilateral cavernosal arteries by color Doppler ultrasonography and intracavernous injection of prostaglandin E1 before and after the medication.

After 4 weeks of tadalafil treatment, IIEF-5 scores and PSVs were remarkably improved in all the four groups as compared with the baseline (P < 0.01), significantly higher in Group C than in D (P < 0.01), but with no significant differences between A and B.

Oral tadalafil can improve PSV and hence penile erection in ED patients either at a low or a high dose. To reduce side effects and drug cost, the patients with PSV >15 cm/s can be medicated at 5 mg, while those with PSV < 15 cm/s at 10 mg or more on alternate days.