Do Efavirenz And Tenofovir Decrease The Effectiveness Of Regestrone?

Posted on Wed, 31 Dec 2014

Question: Hi,

I am taking regestrone 5mg twice a day to delay my periods for a week. But I am on efavirenz and Tenofovir so do I need to increase the dose of regestrone as efavirenz and Tenofovir decrease regestrone levels in blood.

Thanks.

Answered by Dr. Prof. Kunal Saha (1 hour later)

Brief Answer:
Dose adjustment recommended

Detailed Answer:
Hi,

Thanks for asking on HealthcareMagic.

Regestrone contains norethisterone which is basically a low dose oestrogen. Enzyme inducers like efavirenz and tenofovir may reduce the blood levels of such medicines by 40-75 %. So, dose adjustment is preferable. Ideally double the dose would be reasonable, but please go for dose adjustment only under the guidance of your treating physician.

Regards,

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Above answer was peer-reviewed by : Dr. Raju A.T