How Medication Absorption Varies by Application Method: A Pharmacokinetic Overview
Medication absorptionis the process by which a pharmaceutical substance travels from its site of administration into the systemic circulation. The efficiency, speed, and extent of this process—collectively known as bioavailability—are fundamentally determined by the "route of administration." Whether a substance is ingested, applied to the skin, or delivered via the respiratory tract, it must navigate distinct biological barriers and metabolic checkpoints. This article provides a neutral, science-based exploration of how different application methods influence the movement of molecules within the human body. We will examine the physiological hurdles of the gastrointestinal tract, the barrier functions of the skin, and the rapid exchange mechanisms of the pulmonary and circulatory systems. The following sections follow a structured trajectory: defining the parameters of absorption, explaining the core mechanisms of specific delivery routes, presenting a comprehensive comparison of biological trade-offs, and concluding with a technical inquiry section to address common questions regarding administration science.
By Ling Xiu Chen