Intramuscular Injection
A method of drug administration where the compound is injected directly into a muscle. Intramuscular injection is used for certain peptide depot formulations that require slow, sustained absorption — including octreotide LAR (monthly), leuprolide depot, and triptorelin.
Technical Context
IM injection places drug within skeletal muscle tissue, which has richer blood supply than subcutaneous tissue, potentially allowing faster absorption for some formulations. However, for depot formulations, the IM route provides a large tissue volume for microsphere or gel implantation. Preferred sites: deltoid, vastus lateralis, ventrogluteal, dorsogluteal. Needles are typically 21-23 gauge, 25-38mm. Octreotide LAR (PLGA microspheres) must be administered IM in the gluteal muscle using a specific preparation technique. Leuprolide depot and triptorelin depot formulations are also IM. Healthcare professional administration is generally required for IM injections, which is a disadvantage compared to SC self-injection.