Effects of strong CYP2D6 and 3A4 inhibitors, paroxetine and ketoconazole, on the pharmacokinetics and cardiovascular safety of tamsulosin
Article first published online: 11 JUL 2011
© 2011 The Authors. British Journal of Clinical Pharmacology © 2011 The British Pharmacological Society
British Journal of Clinical Pharmacology
Special Issue: Uropharmacology Themed Section
Volume 72, Issue 2, pages 247–256, August 2011
How to Cite
Troost, J., Tatami, S., Tsuda, Y., Mattheus, M., Mehlburger, L., Wein, M. and Michel, M. C. (2011), Effects of strong CYP2D6 and 3A4 inhibitors, paroxetine and ketoconazole, on the pharmacokinetics and cardiovascular safety of tamsulosin. British Journal of Clinical Pharmacology, 72: 247–256. doi: 10.1111/j.1365-2125.2011.03988.x
- Issue published online: 11 JUL 2011
- Article first published online: 11 JUL 2011
- Accepted manuscript online: 15 APR 2011 10:00AM EST
- Received , 13 August 2010 , Accepted , 5 April 2011 , Accepted Article , 15 April 2011
- orthostatic challenge;
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT
• Tamsulosin metabolism involves both CYP2D6 and 3A4. However, data on potential drug–drug interactions between tamsulosin and inhibitors of CYP2D6 and 3A4 are limited and information on potential pharmacodynamic consequences of such pharmacokinetic interactions is missing.
WHAT THIS STUDY ADDS
• This study provides information on the drug–drug interactions of tamsulosin with strong CYP2D6 and strong CYP3A4 inhibitors after single dose administration in healthy subjects.
AIM To determine the effect of the strong CYP2D6 inhibitor paroxetine and strong CYP3A4 inhibitor ketoconazole on the pharmacokinetics and safety (orthostatic challenge) of tamsulosin.
METHODS Two open-label, randomized, two-way crossover studies were conducted in healthy male volunteers (extensive CYP2D6 metabolizers).
RESULTS Co-administration of multiple oral doses of 20 mg paroxetine once daily with a single oral dose of the 0.4 mg tamsulosin HCl capsule increased the adjusted geometric mean (gMean) values of Cmax and AUC(0,∞) of tamsulosin by factors of 1.34 (90% CI 1.21, 1.49) and 1.64 (90% CI 1.44, 1.85), respectively, and increased the terminal half-life (t1/2) of tamsulosin HCl from 11.4 h to 15.3 h. Co-administration of multiple oral doses of 400 mg ketoconazole once dailywith a single oral dose of the 0.4 mg tamsulosin increased the gMean values of Cmax and AUC(0,∞) of tamsulosin by a factor of 2.20 (90% CI 1.96, 2.45) and 2.80 (90% CI 2.56, 3.07), respectively. The terminal half-life was slightly increased from 10.5 h to 11.8 h. These pharmacokinetic changes were not accompanied by clinically significant alterations of haemodynamic responses during orthostatic stress testing.
CONCLUSION The exposure to tamsulosin is increased upon co-administration of strong CYP2D6 inhibitors and even more so of strong 3A4 inhibitors, but neither PK alteration was accompanied by clinically significant haemodynamic changes during orthostatic stress testing.