phentermine under the direction of a weight loss clinic. Unfortunately, I seemed to have developed a very quick tolerance to the 37.5mg administered and feel greatly discouraged. I've noticed from a few of the comments that it appears there are different types of Phentermine? Adipex-P and also Ionamin, that has been discontinued. Also, could anyone rate the weight loss drug Meridia in comparison to Adipex-P Phentermine. I sometimes wonder if I have been duped by this weight loss clinic having really purchased a placebo?