Glossary
Intramuscular
Also written IM, im injection
Into muscle rather than the fat beneath the skin. A faster and better-perfused route, needing a longer needle.
Muscle is far better supplied with blood than subcutaneous fat, so absorption is quicker. For a compound whose effect depends on reaching a level fast that can matter; for most peptides described here it changes little that has been measured.
The trade is practical. Intramuscular injection needs a longer needle, a different technique and a site with enough muscle mass, and it is more uncomfortable. That is why almost everything in this category is given subcutaneously by default.
Where a compound's sources describe both routes, our profiles say so. Where they describe only one, choosing the other is a decision without evidence behind it.
Relevant compounds
Related terms