A comparison of the efficacy and tolerability of tadalafil 10 mg and 20 mg in Japanese patients with severe erectile dysfunction.
BACKGROUND
Tadalafil is a phosphodiesterase type 5 inhibitor with documented efficacy in the treatment of erectile dysfunction (ED).


OBJECTIVE
To compare the efficacy and tolerability of tadalafil 10 mg and 20 mg in men with severe ED.


METHODS
A prespecified subgroup analysis was conducted to compare the efficacy of tadalafil 10 and 20 mg measured by the International Index of Erectile Function (IIEF) erectile function (EF) domain and Sexual Encounter Profile (SEP) among patients with severe ED (EF domain score = 1-10) in a Japanese placebo-controlled study (PCT). We also analyzed the efficacy of the two doses in men with severe ED post hoc by pooling data from three tadalafil clinical trials that evaluated these doses using a similar study design (three placebo-controlled trials), and evaluated (post hoc) the presence of organic comorbidities in patients with different levels of response to tadalafil 10 or 20 mg.


METHODS
Mean change in the IIEF-EF domain and mean per-patient changes in percent "yes" responses to SEP Question 2 (SEP2) and Question 3 (SEP3).


RESULTS
Patients with severe ED in the Japanese study experienced numerically greater increases (improvements) when taking tadalafil 20 mg compared with 10 mg in the IIEF-EF domain (14.3 vs. 12.4; P = 0.355), SEP2 (60% vs. 57%; P = 0.781), and SEP3 (61% vs. 49%, P = 0.196). When sufficiently powered, these observations reached statistical significance in the three PCTs: patients with severe ED experienced greater increases when taking tadalafil 20 mg compared with 10 mg in the IIEF-EF domain (13.6 vs. 10.4; P = 0.014) and SEP3 (56% vs. 43%, P = 0.019). Both doses were well tolerated.


CONCLUSIONS
Patients with severe ED, and especially those with an organic comorbidity, may derive greater clinical benefits from tadalafil 20 mg compared with 10 mg.
Marumo
Ken
K
Department of Urology, Tokyo Dental College, Ichikawa General Hospital, Chiba.
Imaoka
Takeshi
T
Lilly Research Laboratories Japan, Kobe, Japan.
Fujimoto
Kenjiro
K
Lilly Research Laboratories Japan, Kobe, Japan.
Watts
Steven
S
Lilly Research Laboratories, Indianapolis, IN, USA.
Stothard
Diane
D
Lilly Research Laboratories, Indianapolis, IN, USA.
McGill
James
J
Lilly Research Laboratories, Indianapolis, IN, USA. Electronic address: jmcgill@lilly.com.
D000328:Adult; D002243:Carbolines / Q000009:adverse effects / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D010410:Penile Erection; D010726:Phosphodiesterase Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D012107:Research Design; D012720:Severity of Illness Index; D000068581:Tadalafil; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000627:therapeutic use
D002243:Carbolines; D010726:Phosphodiesterase Inhibitors; D014665:Vasodilator Agents; D000068581:Tadalafil