intracutaneous

Intracutaneous refers to something that occurs within the skin. Specifically, it denotes the injection or administration of a substance into the dermis, the layer of skin situated between the epidermis and the subcutaneous tissue. This method of administration is distinct from subcutaneous injections, which are given into the fatty tissue below the dermis, or intramuscular injections, which target the muscle layer.

The intracutaneous route is characterized by its slow absorption rate. This property makes it particularly useful for certain diagnostic tests and vaccinations. For example, the Mantoux test, used to screen for tuberculosis infection, involves an intracutaneous injection of tuberculin purified protein derivative (PPD). The resulting wheal or raised bump at the injection site is then observed for a reaction over a period of 48 to 72 hours. Similarly, allergy testing often utilizes intracutaneous injections of potential allergens to assess hypersensitivity.

In terms of vaccination, some vaccines are administered intracutaneously to elicit a localized immune response. The small volume of fluid typically injected intracutaneously also contributes to the slow absorption and sustained contact with the immune cells present in the dermis. This route requires precise technique to ensure accurate placement within the dermal layer, as injection too deep can lead to faster absorption and reduced efficacy for diagnostic purposes, or different immune responses.