Drugs can be administered through various routes, such as enteral, parenteral, and topical. The route choice depends on the drug's properties and the therapeutic aim. Enteral administration delivers a drug through the gastrointestinal or GI tract. The drug can be administered perorally, or swallowed by mouth, sublingually or placed under the tongue, or buccally, that is placed on the cheeks' inner lining. Perorally administered drugs take time to get absorbed and reach the systemic circulation. So they usually have the slowest onset of action. Parenteral administration delivers the drug directly into the circulation. It can be injected intravenously or through the veins, intramuscularly or through the muscles, or subcutaneously under the skin. Intravenous drugs have high bioavailability and rapid onset of action. This route is often used during emergencies. In topical administration, the drug is applied directly to an area of the skin or mucous membrane through ointments or sprays. The absorption of the drug depends on its properties and the vascularity of the local tissue.