Yes, that is rather old now.
I have been trying to find info. on a small trial I think in Germany ................Ah, David must have read my mind and phoned me up! He says it involved three people who were to undergo a brain operation and allowed a sample to be taken to biopsy. They were given roxithromycin for a few days previously. To great surprise it was found in very large amounts in the brain tissue, which is far more important than the surrounding fluid.
Anyway, I have been taking it since two weeks into starting the treatment. After six months I changed from doxycycline to rifampicin, but wished I hadn't really, because my walking really went off for a couple of weeks. Now that I am on intermittent treatment, I am taking doxycycline and roxithromycin, which I find by far the best option. I mean, it enables me to walk in a straight line!
I would say that you are having such a hard time of it anyway, that you need as much immunomodulation as possible: you don't get any from rifampicin.