Which routes are commonly used for parenteral drug administration?

Parenteral drug administration refers to any route of drug delivery that bypasses the gastrointestinal tract, which includes methods directly involving injections or implantations of medication. The commonly recognized routes for parenteral administration include intravenous (IV), intramuscular (IM), and subcutaneous (SC).

Intravenous administration allows for immediate delivery of medication directly into the bloodstream, offering rapid onset of action and precise control over drug levels in the body. Intramuscular injections deposit the drug into the muscle tissue, allowing for faster absorption compared to oral routes, although the onset of action is slower than intravenous methods. Subcutaneous administration involves injecting the medication into the fatty tissue beneath the skin, which provides a slow and steady absorption rate.

The other options include routes that are not categorized as parenteral. Oral, sublingual, rectal, transdermal, buccal, inhalation, and intranasal are all non-parenteral or different modes of administration where drugs are absorbed through the gastrointestinal tract, skin, or respiratory system. Therefore, the second choice clearly encompasses the primary routes that qualify as parenteral, highlighting their significance and utility in clinical settings.