I take Vitamin C orally too. According to various things I've read, (which was 10+ years ago, so sorry if I don't explain it too well,) Vit C saturates the bodies tissues / organs better when taking intraveniously. The B vitamins are suposed to be absorbed quicker and better too especially if there's a deficiency.
I guess I should read up again so it's clear in my head! Thanks for the link (-: