In which order do the parenteral methods of medication administration have onset of action from fastest to slowest?

The correct order of parenteral methods of medication administration from fastest to slowest onset of action is indeed intravenous, intramuscular, subcutaneous, and intradermal.

When medications are administered intravenously, they enter the bloodstream directly, leading to an immediate effect since there is no absorption phase. This is crucial in emergency situations where rapid drug action is needed.

Intramuscular administration follows, as the medication is injected into a muscle, where it is then absorbed into the bloodstream more rapidly than from subcutaneous tissue due to the better blood supply in muscles. This method is often used for vaccines and certain medications that need to be absorbed quickly.

Subcutaneous administration has a slower onset than intramuscular because the medication is injected into the fatty tissue just beneath the skin, which has a less extensive blood supply compared to muscles. The absorption rate can be affected by factors such as the area of injection and tissue perfusion.

Intradermal administration has the slowest onset of action, as the medication is injected into the dermis, the layer of skin below the epidermis. The absorption of drugs in this layer is slower due to minimal blood supply and is primarily used for allergy tests or vaccinations like the tuberculin test.

This precise chronology