Avorna Duo Drug Interactions

There have been no drug interaction studies for AVORNA-DUO. The following statements reflect the information available on the individual components.
Pharmacokinetic interactions: Interactions with CYP450 enzyme system: Dutasteride: Dutasteride is metabolized by CYP3A4. A reduction in clearance by concomitant administration of CYP3A4 inhibitors is regarded as clinically irrelevant in view of the wide therapeutic window. In vitro, dutasteride is not metabolised by CYP1A2, CYP2A6, CYP2D6, CYP2E1, CYP2C8, CYP2C9, CYP2C19 and CYP2B6. Under in vitro conditions, dutasteride has no inhibitory effect on cytochrome P450 enzymes.
Tamsulosin: Concomitant administration of tamsulosin with CYP3A4 or CYP2D6 enzyme inhibitors may lead to increased tamsulosin exposure. Concomitant administration of ketoconazole (a potent CYP3A4 inhibitor) resulted in an increase of the C_max and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively.
Concomitant administration of paroxetine (a potent CYP2D6 inhibitor) caused an increase of the C_max and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively. The effects of co-administration of both a CYP3A4 and a CYP2D6 inhibitors with tamsulosin have not been evaluated clinically, however, there is a potential for significant increase in tamsulosin exposure.
Interactions with oral anticoagulants: Dutasteride: Dutasteride did not show any interaction with the plasma protein binding of warfarin, acenocoumarol or phenprocoumon in vitro.
Tamsulosin: No study has been conducted on interactions between tamsulosin hydrochloride and warfarin. Tamsulosin has no effect on the pharmacokinetics or efficacy of acenocoumarol in healthy subjects. The effect of acenocoumarol on the pharmacokinetics of tamsulosin has not been investigated. There are no interaction studies with phenprocoumon. The INR values of patients on oral anticoagulation therapy should be closely monitored for 2-3 months when starting or stopping treatment with AVORNA-DUO.
Other pharmacokinetic interactions: Dutasteride: No clinically significant pharmacokinetic or pharmacodynamic interactions have been observed between dutasteride and tamsulosin, terazosin, warfarin, digoxin, and cholestyramine.
In vitro, dutasteride did not displace diazepam or phenytoin from plasma protein binding and in turn was not displaced by them either.
Tamsulosin: Concomitant administration of tamsulosin hydrochloride and furosemide produced an 11-12% reduction in the C_max and AUC of tamsulosin hydrochloride; however, these changes are clinically irrelevant and no dose adjustment is necessary.
Tamsulosin had no effect on the pharmacokinetics of atenolol, digoxin, enalapril, nifedipine, or theophylline.
Pharmacodynamic interactions: Tamsulosin: Based on published data, studies on hypertonic patients whose blood pressure was stable with atenolol, enalapril or nifedipine, tamsulosin did not have a relevant effect on blood pressure compared to placebo.