Absorption
How a swallowed drug actually gets into your blood — and what slows it.
The Drug's Journey: What Absorption Really Is, and How a Drug Crosses Your Cells
You swallow a tablet for a headache. It doesn't know where your head is. Yet 30 minutes later the pain fades. Between the swallow and the relief lies one of the most underestimated journeys in medicine — absorption. Let's follow the drug, step by step, and never forget how it works.
What Controls How Much and How Fast: pH, pKa, First-Pass and Bioavailability
In Part 1 the drug learned HOW to cross a membrane. Now the harder question: why does the same drug act in 15 minutes on an empty stomach but 45 after a meal — and why is a tiny nitroglycerin tablet placed under the tongue instead of swallowed? The answers are pH, surface area, blood flow, formulation, and the liver's first tax. Master these and you can predict a drug's behaviour before you ever prescribe it.
