There are various ways you can absorb a molecule into the body such as the transdermal or topical application on the skin, applying through the rectum, injecting through the skin, applying through the vagina, or applying through the skin inside the mouth. These are skin surfaces that can absorb the molecules of peptides just like swallowing into the stomach where they get absorbed through the stomach lining. Here are some advantages and disadvantages of each method:


Using a little pointy needle to pass molecules into your body is one of the most effective methods of absorption because the molecule bypasses any potential barriers that may prevent easy and fast absorption. The needle will pass the molecule into the body where it will be distributed through the lymph system and through the blood to all body cells. It’s effective because everything that you want will be passed into your body system. However, depending on the size of the needle that you’re using, it may or may not hurt. If the molecule is an oil base, you may require a needle with a large diameter in order to pass the fat molecule effectively into the body. But if what you’re using is in fluid form, then using a thin insulin needle that doesn’t hurt is a good option.


You can apply the molecule on different parts of the body to experience different effects. Depending on the solubility and size of the molecule that you’re applying, it will be absorbed into your body system. You can mix it with a gel or cream for effective application. For example, people who are struggling with nicotine withdrawal symptoms can apply nicotine on the skin. Growth hormone secreting peptides can also be applied and absorbed through the skin. The disadvantage of transdermal application is that the bioavailability and absorption of the cream vary from one person to another because skin types have different absorption capabilities. Furthermore, there is no way you can predict how well someone can absorb a cream. About 10-20 percent of people don’t absorb creams well, and thus the bio-availability of this method is low.


The skin membrane in your mouth is much thinner and highly absorbent as compared to the skin on the outside of your body. You can spray the molecules in your mouth for absorption as long as you don’t swallow them. You’ll experience disadvantages of some of the peptides that are not swallowed if you swallow the molecules.


The work of your gut is to break down the peptides into their smaller amino acid constituents for absorption. There are certain peptides that your body cannot break, and hence you should swallow them. Unlike the other methods discussed in the top article, the oral delivery method has a high bioavailability similar to that of an injection. The molecules that you swallow in a troche form will not be active in your body since most peptides used for hormone secretion are broken down. Therefore, when using a peptide as lozenges or troche, ensure that you keep it in the mouth for as long as you can without mixing it with saliva so as to ensure that it has been absorbed through the lining of the mouth as an intact molecule.

Rectal and vaginal

There are different cultures in the world that don’t encourage this type of application for medication. However, it’s good to use these two options when the patient has problems like vomiting where he or she can’t manage an oral application effectively.