Intramuscular injection is a parenteral route of administration of drugs, in which the drug enters the body by injecting the injection solution through a syringe into the muscle tissue. After the intramuscular injection, the drug enters the bloodstream by sucking the drug in the vascular bed of the skeletal muscle. Since the muscular system is better than the subcutaneous tissue, then, with intramuscular injection, the effect of the drug usually begins faster than with subcutaneous, but slower than intravenous.
The use of intramuscular injection is the most common form of parenteral administration of drugs due to the good vascularization of skeletal muscles, facilitates the rapid absorption of drugs; as well as in connection with the simplicity of the technique of introduction, which makes it possible to apply this method to persons without special medical training, after mastering the relevant skills.
Intramuscular injection can also be used to administer oily solutions of drugs or suspensions. Usually, the drug is administered intramuscularly, when there is no need to obtain immediate effect from the administration of the drug; when administration causes the emergence of phlebitis or thrombophlebitis, and subcutaneous administration causes the formation of infiltrates and abscesses at the site of administration.