Pharmacokinetics, Pharmacodynamics, and Prescribing Considerations

Vocabulary practice flashcards generated from the Pharmacokinetics, Pharmacodynamics, Prescribing Considerations, Lifespan Considerations, and Pharmacogenomics lecture notes.

Pharmaceutics

The study of how drug dosage forms influence drug action, focusing on formulation, solubility, rate of dissolution, and physical/chemical stability.

Pro-drug

An inactive drug formulation that must undergo biochemical alteration (metabolism) within the body to be converted into its active therapeutic form.

Bioavailability

The fraction or percentage of an administered drug dose that enters systemic circulation intact, determined by route of administration and membrane passage.

P-glycoproteins (PGPs)

Transmembrane efflux transport proteins (also known as MDR1s or ABC) that actively pump drugs out of cells, decreasing intracellular drug absorption in tissues like the GI tract, liver, and blood-brain barrier.

pH Partitioning (Ion Trapping)

The phenomenon where drugs accumulate on the side of a membrane with a pH that causes them to ionize, trapping them because ionized molecules cannot cross back through lipid membranes.

Volume of Distribution ($V_d$)

A theoretical parameter representing the total fluid volume needed to contain the total drug amount in the body at the same concentration as plasma, calculated as $\text{V}_d = \frac{\text{dose}}{\text{concentration}}$.

Cytochrome P450 (CYP450)

A major family of liver microsomal enzymes (primarily groups CYP1, CYP2, and CYP3) responsible for metabolizing drugs, with CYP3A4 metabolizing approximately $50\%$ of all clinical drugs.

Phase I Metabolism

Hepatic enzymatic reactions (oxidation, reduction, or hydrolysis) that unmask or introduce polar functional groups onto a drug molecule.

Phase II Metabolism

Conjugation reactions (such as glucuronidation by UGT enzymes) that attach a highly polar compound to a drug to increase water solubility for excretion.

First-Pass Effect

The extensive rapid hepatic metabolism of an orally ingested drug during its initial passage through the portal circulation, reducing the amount that reaches systemic circulation.

Enterohepatic Recirculation

The process in which a glucuronidated drug excreted into bile is cleaved back into free drug by intestinal $\beta\text{-glucuronidase}$ and reabsorbed across the intestinal wall back into the liver.

PS-PORCS

A mnemonic representing major hepatic CYP enzyme inducers: Phenytoin, Smoking, Phenobarbital, Oxcarbazepine, Rifampin, Carbamazepine, and St. John's Wort.

PACMAN (with Grapefruit Juice)

A mnemonic representing major hepatic CYP enzyme inhibitors: Protease inhibitors, Azole antifungals, Cimetidine, Macrolides, Amiodarone, Non-dihydropyridine CCBs, and Grapefruit Juice.

Minimum Effective Concentration (MEC)

The plasma concentration threshold below which a drug will not produce a therapeutic response.

Therapeutic Range (Index)

The concentration window between the minimum effective concentration and the level that causes toxicity.

Steady State

The physiologic state achieved after approximately 4 half-lives when the amount of drug eliminated equals the amount absorbed.

First-Order Kinetics

Linear pharmacokinetic processes where the rate of drug elimination is directly proportional to plasma drug concentration, keeping clearance and half-life constant.

Zero-Order Kinetics

Non-linear pharmacokinetic processes where a constant amount of drug is eliminated per unit of time regardless of plasma concentration due to saturable elimination mechanisms.

Agonist

A drug that displays affinity for a receptor, binds to it, and stimulates a response mimicking endogenous regulatory molecules.

Competitive Antagonist

An antagonist that binds reversibly to the same site as the agonist, whose inhibition can be overcome by increasing agonist concentration.

Noncompetitive Antagonist

An antagonist that binds irreversibly or to an allosteric site on a receptor, lowering the maximal efficacy ($\text{E}_{max}$) regardless of the agonist dose.

Potency

The dose or amount of drug required to produce a given magnitude of biological effect.

Beers Criteria

A clinical guideline listing potentially inappropriate medications to avoid or use with caution in older adult populations.

Controlled Substances Act Schedules

A classification system that categorizes controlled drugs into Schedules I through V based on abuse potential, accepted medical use, and dependency risks.

Risk Evaluation and Mitigation Strategies (REMS)

FDA-mandated safety programs required for high-risk medications to ensure therapeutic benefits outweigh serious risks.

Bioequivalence

The standard requiring a generic formulation's maximum concentration ($\text{C}_{max}$) and area under the curve (AUC) to fall within $80\%$ to $125\%$ of the reference brand-name drug.

Prescription Drug Monitoring Program (PDMP)

A state-level electronic database that tracks controlled substance prescriptions to assist prescribers and prevent medication misuse or diversion.

Side Effect

A nearly unavoidable secondary drug effect produced at therapeutic doses that is generally predictable and dose-dependent.

Toxicity

The degree of detrimental physiologic effects caused by excessive drug dosing.

Idiosyncratic Effect

An uncommon drug response resulting from a individual's specific genetic predisposition.

Paradoxical Effect

A drug reaction that is the exact opposite of the intended therapeutic response.

Iatrogenic Disease

A disease or pathological condition that occurs as a direct result of medical treatment or drug administration.

Physical Dependence

A state of physical adaptation to a drug where discontinuing drug exposure precipitates an abstinence or withdrawal syndrome.

Teratogenic Effect

A drug-induced structural or developmental birth defect resulting from fetal exposure.

Pharmacogenomics (PGx)

The study of how individual genetic variation influences patient responses to drug therapy.

Analytic Validity

The accuracy and precision with which a laboratory test detects a target genetic variant or genotype.

Clinical Validity

The strength and consistency of the relationship between a genetic variant and a specific clinical outcome.

Race-Conscious Medicine

A clinical framework that replaces race-adjusted formulas with patient genetic ancestry, specific biomarkers, and social context.

Pharmacy Deserts

Geographic regions where community residents must travel substantial distances to access pharmacy services and medications.