Ahn TY et al. (2007) Treatment preferences in men with erectile dysfunction: an open label study in Korean men switching from sildenafil citrate to tadalafil. Asian J Androl 9: 760–770

Several oral phosphodiesterase type 5 inhibitors are available for the treatment of erectile dysfunction (ED) and a number of trials have previously identified a patient preference for tadalafil over sildenafil. Ahn and co-workers have investigated the underlying reasons for treatment preferences among Korean men with ED.

A total of 160 men with a history of sildenafil use were switched to tadalafil for 8 weeks. The median duration of sildenafil use before enrollment was 585 days (range 43–2,016 days). Four patients (2.5%) did not complete the study. Of the remainder, 115 (73.7%) opted to take tadalafil during a treatment-extension phase, whereas 41 (26.3%) opted for sildenafil (P <0.001).

Psychosocial elements of ED were examined using the validated Psychosocial and Interpersonal Relationship Scales (PAIRS). After patients switched to tadalafil, a significant decrease in the PAIRS time-concern domain score was observed (P = 0.002). The time from dose to sexual attempt also indicated a larger window of opportunity for sexual activity for men taking tadalafil (0–15 h) than for those taking sildenafil (0–6 h). Decreased concerns about time in relation to sexual activity might be a cause of the observed patient preference for tadalafil.

In contrast to previous results, including those from East Asian populations, mean PAIRS scores for spontaneity and self-confidence domains did not change when patients were switched to tadalafil, possibly, the authors suggest, owing to characteristics unique to the Korean culture.