Biopharmaceutics and Kinetics

The study of how a drug's properties affect its absorption into the body.

The study of how the body processes a drug over time, including absorption, distribution, metabolism, and elimination.

The study of how a drug interacts with the body to produce its effects.

The primary way many drugs enter the body, moving from a high concentration area to a low concentration area across a membrane.

The cell's outer layer composed of a lipid bilayer, acting as a barrier to most water-soluble molecules.

A measure of how much drug reaches the bloodstream after administration, calculated by analyzing the area under the drug concentration-time curve.

The maximum concentration of a drug in the bloodstream after administration.

The time it takes for a drug to reach its maximum concentration in the bloodstream.

The range of drug concentrations in blood between the minimum effective concentration (MEC) and the maximum safe concentration (MSC).

The time it takes for the concentration of a drug in the bloodstream to decrease by half.

The tendency of a drug to move between watery environments (like blood) and fatty environments (like cell membranes). A high partition coefficient means the drug prefers to be in the lipid environment.

The state of a drug being either charged (ionized) or uncharged (unionized). Ionized drugs have trouble passing through cell membranes, which are mostly made of fat.

A measure of how acidic or basic a drug is. Important because it influences the drug's ionization state, which affects its ability to cross cell membranes.

A type of transport across cell membranes that doesn't require energy. It's influenced by concentration gradients - the drug moves from an area of high concentration to an area of low concentration.

A type of transport across cell membranes that requires energy. It allows substances to move against their concentration gradient.

A process where cells take in substances from their environment by engulfing them.

A process where cells release substances from their interior to the outside by packaging them into vesicles.

Time required for the concentration of a drug in the body to decrease by half, after absorption has stopped. This is important for determining how long a drug will stay in the body and how often it needs to be dosed.

The maximum concentration of a drug in the blood after administration. It indicates the peak level of drug in the body.

The time it takes for a drug to reach its maximum concentration in the blood. It tells us how quickly the drug is absorbed.

The amount of drug that reaches the bloodstream per unit of time after administration. It reflects both the absorption rate and the extent of absorption.

Two dosage forms of the same drug are considered bioequivalent if they are absorbed at the same rate and extent.

A state where the concentration of a drug in the body remains constant over time after repeated doses. This is achieved when the rate of drug administration equals the rate of drug elimination.

The binding of a drug to plasma proteins in the blood reduces the concentration of free (active) drug available to reach its target site. This can affect the drug's efficacy.

The process by which a drug moves from the site of administration into the systemic circulation.

The condition where the blood constantly draws in the drug from the site of absorption, ensuring a high concentration gradient for optimal absorption.

The fraction of a drug dose that reaches the systemic circulation after administration.

The process by which a drug distributes throughout the body's fluids and tissues.

The fluid component of blood, containing proteins like albumin, responsible for carrying and transporting many drugs.

The fluid that surrounds cells and acts as a medium for exchange of nutrients and waste.

The fluid found inside cells, responsible for cellular processes.

An imaginary volume of fluid that a drug appears to distribute into, calculated based on the drug's concentration in the plasma.

The volume of distribution (Vd) is a theoretical volume that represents the total amount of drug in the body at a given time, divided by the concentration of the drug in the plasma. It reflects how widely the drug distributes throughout the body.

Drugs with high lipid solubility tend to have a larger Vd because they readily distribute into tissues other than blood, like fat and muscle. This means less drug remains in the blood, leading to a higher Vd.

Drugs with high water solubility tend to have a lower Vd because they remain primarily in the blood, leading to a lower Vd.

Biotransformation is the chemical changes a drug undergoes within the body, often by enzymes.

Metabolism is the process of altering a drug's structure by chemical reactions in the body, usually to make it more water-soluble for easier removal.

The liver is a major organ responsible for drug metabolism, using enzymes like CYP450 to alter the drug's structure.

The kidneys are the main organs for drug elimination, filtering waste products, including drugs, from the bloodstream.

The half-life of a drug is the time it takes for the drug's concentration in the bloodstream to decrease by half.

Drugs with short half-lives need more frequent dosing to maintain therapeutic levels, while drugs with long half-lives require less frequent dosing.

The CYP450 enzyme system in the liver can generate active metabolites with properties different from the original drug, potentially impacting the drug's effects.