Minocycline is more effective and much more expensive than Tetracycline, although I believe Minocycline is a form of Tetracycline. The reason it is more effective is because mincycline is better absorbed or something like that.
As far as I understand, minocycline is a tetracycline antibiotic. I believe minocycline is 'stronger' (for lack of a better word). I guess they are structurally similar yet different. In my case tetracycline didn't work, but minocycline does. Good luck. <IMG SRC="http://www.healthboards.com/ubb/smile.gif"> And to be sure, ask you DR.