medical

Absorption

the amount of medication that enters the bloodstream, or systemic circulation.

Bioavailability

the percentage of an administered dose of a medication that reaches the bloodstream.

Biopharmaceutics

the study of the manufacture of medications for effective delivery into the body. It includes the relationships between the physical and chemical properties of a drug, the dosage form in which the drug is given, the route of administration, and the effects of properties and dosage on the rate and extent of drug absorption.

Clearance

—the removal of plasma that is completely cleared of drugs per unit of time. It combines the elimination rate with the flow of a drug through the organs of elimination (ie, liver and kidneys). It is usually measured in mL/min or L/hr.

Creatinine clearance

an estimate of kidney function that is often used when determining drug doses that need to be adjusted in a patient with reduced kidney function.

Cytochrome P450 (CYP450

a group of enzymes that metabolize drugs in the human body

Disintegration

the breakdown of medication from its original solid formulation.

Dissolution

the dissolving of medication into solution, usually in the stomach and intestinal tract

Drug interaction

the impact of a drug or food product on the amount or activity of another drug in the body. This interaction can result in enhanced, reduced, or new activity of the drug in the body

Elimination

the removal of a drug from the body, mainly in the urine or feces.

Excretion

the irreversible removal of a drug or metabolite from a body fluid. The most common location of drug excretion in the body is the kidneys; the biliary tract is another important route of excretion

First-pass metabolism

the metabolism (breaking down) of orally ingested medications by the liver and small intestine before they reach the main bloodstream.

Half-life

the time that it takes for 50% of a drug to be eliminated from the body

Loading dose

a larger first dose of a drug given to quickly achieve a high drug concentration in the body

Metabolism

the breakdown of medication in the body

Metabolite

a breakdown product of a medication that has undergone metabolism.

Narrow therapeutic index (NTI)

as defined by the US FDA, narrow therapeutic index (NTI) drugs are “drugs where small differences in dose or blood concentration may lead to serious therapeutic failures and/or adverse drug reactions that are life-threatening or result in persistent or significant disability or incapacity.

Pharmacodynamics

—the study of the relationship between the concentration of a drug in the body and the response or outcome observed or measured in a patient

Pharmacogenomics

the study of how a person’s genetic makeup can impact the pharmacokinetics and pharmacodynamics of a drug.

Pharmacokinetics

the study of the movement of a drug through the body during the following phases: absorption, distribution, metabolism, and excretion

Therapeutic range

the blood levels (between maximum and minimum) at which most patients receive a medication’s desired effect with minimal side effects.

Volume of distribution

the extent of a medication’s outreach to various tissues and spaces throughout the body.

ADME

absorption, distribution, metabolism, and excretion

ORAL DRUG

Oral drug → GI tract/intestine → Portal circulation → Liver → Systemic blood → Body tissues/organs

• After a drug is swallowed, it is absorbed from the intestine into the portal circulation.

• Portal blood carries the drug to the liver first.

• The liver metabolizes (breaks down) some of the drug before it reaches the rest of the body. This is the first-pass effect.

• The unchanged drug + metabolites that remain enter the systemic blood supply.

• The systemic blood distributes the drug to body tissues and organs.

• Drug can move blood ↔ tissues: drug enters tissues from the blood, and drug can also move back from tissues into the blood.