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Sunday, November 29, 2009

A Tale of Two Antibiotics, Part Two

Doxycycline, often marked as vibramycin, is a semisynthetic tetracycline derivative that Pfizer has been pushing since 1967. It works by a mechanism similar to that of the macrolides such as azithromycin, but it binds to a different portion of the ribosome and inhibits a different step in protein synthesis (but with the same result). Because it has been around much longer than azithromycin and it does not have features that would prevent the development of resistance (taken twice a day for ten days; half life = 18 hours), it is no longer effective on some types of bacteria. However, it is still very potent against a broad spectrum of infections, including anthrax, black plague, Legionnaires' disease, syphilis, lime disease, and malaria. Tetracyclines must be taken a minimum of one hour before or two hours after eating to be well-absorbed, are inactivated by high blood levels of calcium, magnesium, or iron, and can cause severe photosensitivity, birth defects, and hepatotoxicity.

But it works!

And hey, that's what you get for getting sick in the first place.


  1. There is a certain irony that the antibiotic resistance that you have been complaining about for Rhodobacter, ends up being the one that cures your internal pestulance. Speaking of which, when are you going to get transformed rhoddobacter with the new plasmid!?

  2. Winter break(?)...

    It helped that I had the choice to stay out of the light!