Medicines that must be delivered directly into the body through the skin are called injectible medication.
There are two areas medicines are placed. The subcutaneous area is just under that skin, but not in the muscle. When the needle is placed deeper, it is targeted for the muscle itself, called intramuscular.
The choice of whether the injection should be subcutaneous or intramuscular has to do with the medication being injected, and how well it is absorbed in either site.
- Insulin is perhaps the most commonly used subcutaneous injection
- Vaccinations or antibiotics are generally given intramuscularly.
Certain medications will be deactivated by the body (usually the liver) so quickly that to give them orally is worthless. These are usually given through injection
- Testosterone for replacement of male hypogonadism is given intramuscularly.