Pharmacokinetics Quiz on Drug Dosage and Dynamics

The rate constant of elimination in a patient with uremia relative to a normal patient, often expressed as a percentage. It represents the extent to which renal function affects drug elimination.

The amount of drug that should be administered at a given time interval, considering the patient's individual pharmacokinetic parameters and the desired therapeutic effect.

A mathematical approach used to analyze plasma drug concentration data over time. In this method, the data is separated into exponential components representing the different elimination phases (alpha and beta phases).

The elimination half-life of a drug in the central compartment - the time it takes for the concentration in the central compartment to decrease by half. It is related to the elimination rate constant (k) and the volume of distribution (Vd).

A model in pharmacokinetics that describes how a drug distributes in the body, with two compartments representing the central and peripheral compartments. The drug moves between these compartments until reaching an equilibrium state.

The rate constant for the transfer of drug from the central compartment to the peripheral compartment. It determines how quickly the drug moves out of the central compartment to reach the peripheral compartment.

The rate constant for the transfer of drug from the peripheral compartment to the central compartment. It determines how quickly the drug moves back from peripheral tissues to the blood.

The overall elimination rate constant of a drug, which describes how quickly the drug is removed from the body by combined processes. It is influenced by factors like renal excretion and metabolism.

A Scatchard plot with a non-linear curve indicates multiple binding sites for a drug on the target molecule. This is because the binding affinity changes with the increasing concentration of the drug due to multiple different binding sites.

The elimination half-life is the time it takes for the concentration of a drug in the body to reduce by half. It can be calculated from the elimination rate constant, which is the negative of the exponent in the exponential decay function.

The maximum plasma concentration (Cmax) of a drug is the highest concentration reached in the body after administration. For a drug that has a two-compartment model, Cmax can be calculated by finding the maximum value of the function describing its plasma concentration over time.

A prodrug is a medication that is inactive when administered but is converted to an active form in the body. Prodrugs can be used to improve drug delivery, increase bioavailability, or reduce side effects.

Creatinine clearance is a measure of kidney function. It reflects the rate at which the kidneys remove creatinine from the blood. It can be estimated using various formulas that take into account factors like age, sex, and serum creatinine levels.

Osmosis is a process where a solvent, typically water, moves across a semipermeable membrane from a region of high concentration to low concentration to equalize the concentration gradient. In drug delivery, it can be used to control the release of a drug from a formulation.

Erosion is a controlled degradation of a solid oral formulation, where the drug is released as the solid matrix gradually dissolves. This method is used to extend drug release and ensure a consistent drug concentration over time.

Leaching is a process where a drug is extracted from a solid formulation into a surrounding medium, usually an aqueous solution. This can be used to control the release of a drug from a solid matrix.

The ratio of the AUC (area under the curve) obtained after administration of a drug in its oral tablet form to that obtained after administration in its oral capsule form.

The time it takes for the plasma concentration of a drug to decrease by half during elimination.

The volume of distribution is a pharmacokinetic parameter that reflects the apparent volume into which a drug distributes in the body.

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

The rate at which a drug is eliminated from the body. It is often expressed in units of volume per unit time, for example, liters per hour.

The steady-state concentration is the average plasma concentration of a drug that is achieved after repeated dosing at a constant rate.

The process by which a drug's release rate from a formulation is controlled to achieve a specific therapeutic effect.

The amount of drug administered to achieve the desired therapeutic effect.

Polyethylene glycol (PEG) is a polymer that helps liposomes evade phagocytes, increasing their lifespan in the body. It's like a camouflage, making liposomes less visible to the immune system.

An antagonist binds to a receptor but does not activate it. It's like a key that fits the lock but doesn't turn it.

Suspending agents help keep solid particles dispersed in liquid formulations. They prevent settling and promote a uniform dose.

Grapefruit juice can inhibit the metabolism of certain drugs, like simvastatin, leading to higher plasma concentrations.

Highly plasma protein-bound drugs are primarily circulating bound to proteins, making them less readily filtered by the glomerulus. They tend to be excreted slowly.

ATP Binding Cassette (ABC) transporters are involved in active transport of drugs OUT of cells, contributing to drug elimination.

Drugs administered orally are more likely to undergo first-pass metabolism in the liver, having less bioavailability to reach the systemic circulation for biliary secretion.

A drug with low fraction unbound in tissues means it's primarily bound to tissues, limiting its ability to distribute widely. This suggests a low apparent volume of distribution.

The bioavailability of a drug is the fraction of the administered drug that reaches the systemic circulation. It describes the extent to which a drug is absorbed and available to exert its effect.

The area under the curve (AUC) is a measure of the total amount of drug exposure over time. It's calculated by integrating the concentration-time data from a plasma drug concentration profile.

Relative bioavailability is the ratio of AUCs for two different formulations of the same drug. It compares the bioavailability of one formulation to another, usually a standard.

The elimination half-life is the time it takes for the concentration of a drug in the body to decrease by half. It's a measure of how quickly a drug is eliminated from the body.

The steady-state concentration (Css) is the constant concentration of a drug in the body that is achieved after repeated dosing. It's a balance between drug input (dosing) and elimination.

The maximum plasma concentration (Cmax) is the highest concentration of a drug in the plasma that is achieved after administration. It's a measure of the peak concentration of the drug in the body.

The volume of distribution (Vd) is a theoretical volume that describes the distribution of a drug throughout the body. It's calculated as the total amount of drug in the body divided by the plasma concentration.

The Noyes-Whitney equation describes this process, where the drug dissolves from a solid form into a liquid solution. It highlights the factors that influence the rate of dissolution, such as the surface area and the difference in concentration between the solid form and the solution.

The rate constant of drug metabolism refers to the rate at which a drug is transformed into a different chemical compound. For first-order kinetics, the drug's elimination half-life is constant, meaning it takes the same amount of time to eliminate half of the drug concentration.

This equation describes the relationship between the rate of a drug's metabolism and the concentrations of the enzyme and the drug. It helps us understand how these factors affect the speed of the reaction.

When a drug's elimination rate is proportional to its concentration, it follows first-order kinetics. This means the drug is eliminated at a constant fraction per unit time.

The intrinsic clearance of a drug reflects its ability to be cleared by the liver, independent of blood flow. A drug with a higher intrinsic clearance will be metabolized faster.

Hysteresis refers to the lag between the drug's pharmacodynamic effect and its concentration in the body. It can be reduced by using a lower dose to minimize the concentration fluctuations.

Doubling the elimination half-life means it takes twice as long for the drug's concentration to decrease by half. This results in a longer duration of the drug's effect in the body.

A drug is said to be a better candidate for an oral modified-release product if its dissolution is slow compared to the drug's rate of absorption. This is because the slow dissolution rate allows for a sustained release of the drug over a longer period.