Ivabradine is a heart medicine used to treat stable angina pectoris where beta-blockers are not suitable and I understand that it has a half-life of 12 hours.

How therefore could it, when taken o.m., cause severe headaches 18 to 24 hours after taking it?

And why, if taken b.d., does it only cause headaches first thing in the morning?

I have no idea about the first question, but I'm wondering if the second is answered by the fact(?) that ivabradine dilates the bllodvessels in the brain and that that, and a combination of lying down sleeping, causes the bllod to go to the head - resulting in the headache.

Or is the timing of introduction of the new tablet just an unfortunate coincidence?

Thanks.