Article date: March 2010
By: Kwang‐Hee Shin, Yong‐ju Chung, Bo‐Hyung Kim, Tae‐Eun Kim, Hwa‐Sook Kim, Joo‐Youn Cho, In‐Jin Jang, Sang‐Goo Shin, Kyung‐Sang Yu, in Volume 69, Issue 3, pages 307-310
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT
• Udenafil is a phosphodiesterase 5 inhibitor used for the treatment of erectile dysfunction.
• Udenafil is safe and well tolerated in healthy subjects, and effective as treatment for erectile dysfunction.
• In vitro studies have demonstrated that CYP3A4 is the major enzyme responsible for the metabolism of udenafil.
WHAT THIS STUDY ADDS
• The pharmacokinetic characteristics of udenafil in the presence of ketoconazole, a potent CYP3A4 inhibitor, were determined in healthy Korean volunteers.
• Systemic exposure of udenafil was significantly increased when it was administered with ketoconazole.
AIMS Udenafil is a phosphodiesterase 5 inhibitor used for the treatment of erectile dysfunction. It is metabolized to DA‐8164, a major metabolite, by CYP3A4. This study was performed to investigate the effect of ketoconazole, a known CYP3A4 inhibitor, on the pharmacokinetics of udenafil.
METHODS An open‐label, two‐period, fixed‐sequence crossover study was performed in 12 healthy male volunteers. They received a single 100‐mg oral dose of udenafil. Following a 5‐day interval, 400 mg of ketoconazole was administered once a day for three consecutive days. On day 3 of ketoconazole treatment, a second 100 mg of udenafil was dosed concomitantly. Blood samples were collected at time points up to 48 h without ketoconazole treatment and up to 72 h with ketoconazole co‐administration. The plasma concentration of udenafil was determined using liquid chromatography–tandem mass spectrometry.
RESULTS Following ketoconazole co‐administration, the mean Cmax and AUClast of udenafil (95% confidence interval) increased 1.9‐fold (1.60, 2.27) and 3.2‐fold (2.82, 3.63), respectively. The median time to reach the Cmax was delayed in the co‐administrated treatment, while the mean terminal elimination half‐life (t1/2) remained relatively unchanged regardless of ketoconazole co‐administration. The metabolic AUC ratio (AUClast of DA‐8164/AUClast of udenafil) was 1.71 when udenafil was administered alone, and the value decreased to 0.19 when udenafil was dosed in the presence of ketoconazole. Regarding safety assessments, no clinically significant difference or serious adverse event was observed.
CONCLUSIONS The systemic exposure of udenafil increased significantly when it was administered with ketoconazole. Dose adjustment may be required when these drugs are used together.
DOI: 10.1111/j.1365-2125.2009.03601.x
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