Interactions : אינטראקציות

4.5   Interaction with other medicinal products and other forms of interaction
In vitro data that the main active metabolite 20α-dihydrodydrogesterone (DHD) and to less extent also dydrogesterone are primarlily metabolized by CYP3A4.
Substances that increase the clearance of progestogens (less efficacy due to enzyme induction) are for example: barbiturates, phenytoin, carbamazepine, primidone, rifampicin and HIV medication like ritonavir, neviparine and efavirenz, and possibly also products containing the herb St. John’s Worth (hypericum perforatum).
An increase in the clearance of dydrogesterone may lead to a clinical decrease of effect and changes in the bleeding pattern.

Substances with variable effects on the clearance of progestogens:
Many combinations of HIV protease inhibitors and non-nucleoside reverse-transcriptase inhibitors, including combinations with HCV inhibitors could, if concomitantly administered with progestogens, raise or lower the plasma concentrations of the progestogen. In some cases the net effect of these changes could be clinically relevant.

For this reason the product information of HIV/HCV medicines should be consulted, if they are administered concomitantly, to determine potential interactions and any associated recommendations.

Substances that decrease clearance of progestogens (enzyme inhibitors): The clinical relevance of possible interactions with enzyme inhibitors is unknown.
Concomitant use of strong CYP3A4 inhibitors may raise the plasma concentrations of progestogens.