I also wanted to know about the Creatine substitute, I remembered seeing it posted on the web, but they didnt say much about it. I would really appreciate a response so my mom can decide if shell buy it for me or not. In researching your question I looked for medical articles about the safety of creatine. I didn't find any. That means I didn't find any study indicating there was anything unsafe about creatine, but neither was there one establishing its safety, and most especially, I didn't find anything addressing the issue of safety in teens.
Creatine is marketed as a nutritional supplement rather than as a drug.
The FDA rules for nutritional supplements are much less stringent than for medications. That means there is much less study of safety and effectiveness required for nutritional supplements then for medications to be out on the market. There is a lot of profit to be made and the hyped advertising stays just barely within the requirements of law regarding false claims. The questions you should consider are. More isn't always better.