What are the main routes of administration?

Oral (PO), Sublingual (under the tongue), and rectal (these are the digestive routes) IM, SC, IV (these are the parenteral routes) Inhalation (respiratory diseases), Topical (applied to skin/ mucus membrane for local or systematic effects), Transdermal (applied to skin for systemic effects and stay for hours (should be lipophilic in order to get behind the border of epidermis)