3-Physiological Aspects of ADME: Absorption Considerations

This set of flashcards covers key concepts from the lecture on the physiological aspects of drug absorption.

Diffusion

The process by which molecules spread from areas of high concentration to areas of low concentration.

pH

A scale used to specify the acidity or basicity of an aqueous solution.

pKa

The pH value at which half of a substance is ionized.

Ionization

The process by which an atom or molecule gains or loses an electric charge.

Unionized form

The form of a drug that is not charged and can cross biological membranes.

Weak acid

An acid that does not completely dissociate into its ions in solution.

Weak base

A base that does not completely ionize in solution.

Acidic solution

A solution that has a pH less than 7.

Basic solution

A solution that has a pH greater than 7.

Drug absorption

The process by which a drug enters the bloodstream from its site of administration.

Henderson-Hasselbalch Equation

An equation used to calculate the pH of a buffer solution in relation to the concentration of its acidic and basic components.

Ion trapping

A phenomenon where drugs accumulate in body compartments where the pH favors their ionized form, making them unable to diffuse back across membranes.

Gastric acid

Hydrochloric acid in the stomach that helps in digesting food and dissolving drugs.

Drug interactions

Changes in the effect of a drug when administered in combination with another drug or substance.

Surface area of absorption

The area available for drug absorption which can affect the rate of absorption.

Electrolyte balance

The balance of ions in body fluids which can affect drug action and absorption.

Pharmacokinetics

The study of how drugs move through the body.

Bioavailability

The extent and rate at which the active ingredient or active moiety is absorbed and becomes available at the site of action.

Lipid solubility

The ability of a substance to dissolve in fats, which is essential for diffusion through cell membranes.

Stomach pH

Typically ranges from 1.0 to 3.0, affecting drug ionization and absorption.

Intestinal pH

Ranges from 7.5 to 8.0, where weak bases are better absorbed.