Somatropin is the active ingredient of Human Growth Hormone and it’s contained in every FDA approved brand. Injectable HGH uses this compound mixed with bacteriostatic water to dissolve and works as vehicle to transport the hormone into the body and also as preservative. The amount of water does not affect the effectiveness of the hormone and in some brands you can chose yourself how diluted or concentrated you want your hormone to be as you have to mix the product manually.
There are some studies and researches online that show a comparison between different brands so you can have a better idea of what to expect from each one. These studies are based on testimonies from people that have experience with both brands and share their insights and practical knowledge on the matter.
For new users or for people that are looking to switch from one brand to the other here are some comparisons between different brands that help you chose which way to go.
Remember that like with any other medicine the assimilation and reaction to the product can vary from one person to the other. Also the preexistence of a medical condition can affect the effectiveness or reaction of the product. In any case you can always switch to a different brand or adjust your current dose.