2060 WEEK 3

Biotransformation

The chemical modification made by an organism on a chemical compound.

First Order Kinetics

When the rate of drug metabolism is directly proportional to the concentration of free drug in the body.

Zero-Order Kinetics

When the metabolic rate of a drug remains constant regardless of its concentration.

First-Pass Metabolism

The metabolism of a drug that occurs in the liver before it reaches systemic circulation.

Phase I Metabolism

Metabolic reactions that add or expose functional groups, increasing a drug's polarity.

Phase II Metabolism

Conjugation reactions that add larger chemical groups to drugs to enhance excretion.

Cytochrome P-450

A large family of enzymes primarily responsible for Phase I metabolic reactions.

UDP-glucuronosyltransferases (UGTs)

Enzymes that catalyze the transfer of glucuronic acid, increasing a drug's polarity.

Sulfotransferases (SULTs)

Enzymes that add sulfate groups to substances, increasing their polarity.

Glutathione S Transferases (GSTs)

Enzymes that transfer glutathione, reducing the toxicity of metabolites.

N-acetyltransferases (NATs)

Enzymes that transfer acetyl groups to drugs, affecting their metabolism.

Dosing Rate

The rate at which a drug needs to be administered to maintain a desired plasma concentration.

Half-Life (T1/2)

The time it takes for the concentration of a drug in the plasma to reduce by half.

Transcellular Reabsorption

Reabsorption of substances across both apical and basolateral membranes of renal tubules.

Paracellular Reabsorption

Movement of substances between renal tubule epithelial cells into surrounding capillaries.

Anion Secretion

The secretion of negatively charged organic anions into the renal tubule.

Cation Secretion

The secretion of positively charged organic cations into the renal tubule.

Biliary Excretion

Excretion of drugs through bile, usually for larger or amphipathic drugs.

Pulmonary Drug Excretion

The excretion of drugs primarily through the lungs, often for volatile substances.

Volume of Distribution (Vd)

A pharmacokinetic measurement that indicates how extensively a drug disperses in the body.

Clearance (CL)

The rate at which a drug is removed from the body, combining all elimination mechanisms.

Steady State

The condition where the overall intake of a drug is equal to the elimination, resulting in a stable concentration.

Loading Dose

A higher initial dose of a drug given to quickly achieve a therapeutic concentration.

Enterohepatic Recycling

The process where drugs secreted into bile are reabsorbed back into the circulation.

Acetaminophen Metabolite

A toxic metabolite formed from acetaminophen that can damage the liver.

Ethanol Metabolism

The elimination of alcohol from the body is characterized by zero-order kinetics due to enzyme saturation.

Prodrugs

Inactive drugs that require metabolism to convert into their active form.

Organic Anion Transporters (OATs)

Transporters responsible for moving negatively charged organic anions into renal tubules.

Organic Cation Transporters (OCTs)

Transporters that facilitate the movement of positively charged organic cations into renal tubules.

Functional Groups

Specific groups of atoms within molecules that are responsible for the characteristic chemical reactions.

Hydration Shell

Water molecules that surround a solute in solution, influencing solubility.

Renal Function

The ability of the kidneys to filter and excrete waste products and drugs.

Drug Interaction

A situation where a drug affects the activity of another drug when both are administered together. This can lead to enhanced effects, reduced efficacy, or increased toxicity.

Genetic Polymorphisms (CYP2D)

Variations in DNA that can lead to different responses to drugs among individuals.