PT3001: Introduction to Pharmacology - Pharmacokinetics I: Drug Absorption and Distribution

Vocabulary practice cards for key terms and concepts in Pharmacokinetics Lecture 1 covering the ADME process, administration routes, membrane transport mechanisms, and tissue distribution barriers.

Pharmacokinetics

The study of how the body handles a foreign molecule, described as "what the body does to the drug" through tracking its absorption, distribution, metabolism, and excretion.

Drug Absorption

The movement of a drug from its site of administration into the bloodstream (plasma).

Bioavailability ($F$)

The fraction of administered drug that reaches the systemic circulation; equal to $1$ ($100 proposal percentage$ absorption) for intravascular administration and usually less than $1$ for all other routes.

Drug Distribution

The reversible transfer of a drug from the bloodstream/plasma into extravascular spaces, such as organs, tissues, cells, and subcellular compartments.

Drug Metabolism

The chemical modification of a drug, usually occurring in the liver, to convert compounds into more polar, water-soluble forms.

Drug Excretion

The removal of a drug and its metabolites from the body, primarily through the kidneys, but also via sweat, lungs, and other pathways.

Sublingual Administration

A route of drug administration placed under the tongue that provides fast absorption and action while bypassing gastric pH and first-pass metabolism.

Buccal Administration

A route of administration into the lining of the cheek that offers fast absorption and bypasses gastric pH and first-pass metabolism.

Intravenous (IV) Injection

The fastest route of administration that introduces a drug directly into systemic circulation, providing $100\%$ bioavailability while bypassing absorption and first-pass metabolism.

Percutaneous Administration

Transdermal drug delivery through the skin for systemic use, providing slow and sustained release.

Passive Diffusion

The predominant mechanism of drug absorption where uncharged, lipid-soluble molecules move down their concentration gradient across a lipid bilayer without external energy.

Facilitated Diffusion

A carrier-mediated passive process where specific transport proteins assist polar or charged drug molecules across cell membranes down a concentration gradient without ATP.

Active Transport

A carrier-mediated transport mechanism that utilizes ATP energy to move specific drug molecules across cell membranes against a concentration gradient.

Endocytosis

An energy-dependent mechanism where a cell membrane folds inward to engulf large molecules into vesicles and internalize them into the cytoplasm.

Phospholipid Bilayer

A $7\,\text{nm}$ structural cell membrane barrier consisting of two layers of fat molecules with hydrophobic tails facing inward and hydrophilic heads facing outward.

Albumin

The most abundant plasma protein ($50\%$ to $65\%$ of total plasma protein) that primarily binds acidic drugs such as warfarin.

Blood-Brain Barrier (BBB)

A specialized brain capillary system featuring tight junctions without pores, a continuous basement membrane, and active efflux pumps that strictly restrict drug entry into brain tissue.

P-glycoprotein

An active efflux transporter found in endothelial structures like the blood-brain barrier that actively pumps drugs and toxins back out of tissues.

Metoclopramide

A pro-kinetic drug that increases gastrointestinal motility, leading to faster transit to the small intestine and more rapid absorption of co-administered oral drugs.

Tetracycline

An antibiotic class with a high affinity for calcium that selectively accumulates in bones and teeth.