The answer for this is simple ” Injections are very effective at getting a molecule into your body because you bypass any barriers or any obstructions with a little pointy needle. You inject the molecule straight into your body and then it distributes through your blood and through your lymph system throughout the body to all cells of the body. It’s very effective. Everything you inject is in your body. The bio-availability is effectively 100%, Everything you want to get in, you’ve got in. The difficulty is that it’s an injection and depending on the size of the needle they may or may not hurt. If what you are injecting is in a fluid base, you can use a very thin insulin needle and it’s painless.
Orally ( we would not recommend this )
If you swallow the peptides, the peptides are small proteins and your gut and your stomachs job is to break down any protein or peptide you eat into its small constituent amino acids so that then absorb those amino acids and build up the proteins that you need inside your body. however many of the peptides we use for growth hormone secretion, they are broken down so anything that gets into your stomach or your gut either as a tablet or as an oral spray or a troche form that you swallow will not be active in your body. (This is not effective way as it will be less than 1-2% )