What is the slowest method of drug administration?

The oral route of drug administration is considered the slowest method due to several factors that influence the absorption and onset of action. When a medication is taken orally, it first travels through the gastrointestinal (GI) tract. It must then be absorbed through the intestinal wall into the bloodstream. This process can be significantly affected by various factors, including the presence of food, the formulation of the medication (e.g., tablet or liquid), and the overall health of the digestive system.

In contrast, intravenous administration delivers medication directly into the bloodstream, allowing for immediate effects. Subcutaneous and intramuscular routes also provide faster absorption than oral administration, as they bypass much of the digestive process and allow the drug to enter systemic circulation more quickly. The oral route's reliance on digestion and metabolism before reaching the systemic circulation inherently makes it slower compared to the other methods mentioned.