Question

1. State 10 concepts in "PHARMACOKINETICS" clearly described/defined each concept and provide 1 multiple choice question (5 option choices) on each concept. Provide the answer (clearly highlighted) for each question, and also provide your reasoning/calculations for each choice option.

Answer 1

Pharmacokinetics is the study of the time course of drug absorption, distribution, metabolism and excretion. A drugs effect is often related to its concentration at site of action.

Concepts in pharmacokinetics

• Therapeutic drug monitoring : Throughout drug development process researchers investigate drug deposition to understand pharmacokinetics relation.This allows healthcare expert to adjust dose to achieve optimal drug concentrations in body ,based up on assumptions that there is a correlation between therapeutic effect and plasma concentrations.
• Distribution phenomena : to understand how and why a drug distributed throughout body.The apparent volume of distribution is a measure of where drug is located predominantly in blood, extracellular space or out in tissue.
• Clearance concepts: to understand how and why a drug is cleared from body.Clearance is the volume of blood removed of drug per unit time.It is primary pharmacokinetic parameter along with volume of distribution. The total body clearance is sum of all clearance processes.Clearance and volume together determine drugs half life.
• Intravenous bolus : to understand one compartment body model and how it is used to predict drug concentrations in body over time, after an intravenous bolus dose.The initial concentration at IV bolus administrations is a function of dose and volume of distribution. Knowing initial concentration and drugs half life one can estimate any concentration at any time point.
• Extravascular administration : To understand the effect, on drug concentrations resulting from extravascular drug administration. In this administration drug takes time to enter systemic circulation and some drug may be lost during absorption. It is the most common route of administration.
• Bioavailability : It refers to the rate and extent to which a drug is absorbed and available at site of action.Absorption rates can be zero order ,first order ,second order.Absorption rate will depend on factors such as dosage form and physiologic parameters.
• Intravenous infusion : to understand one compartment model and how it is used to predict drug concentrations in the body over time after intravenous infusion.In this drug is given as a mass over time to vein.In this one can know time to achieve steady state,where concentration do not fluctuate over time.the concentrations achieved at a constant infusion rate, etc.
• Multiple dosing : to understand effect on drug levels of multiple doses of a drug and how dose amount , dosing interval, clearance and volume will affect steady state drug concentrations.
• Hepatic clearance: to understand how drug deposition is impacted by hepatic clearance.Liver is most important organ in body related to clearance of drug or toxin.Variables which affect hepatic clearance like hepatic blood flow, BMI binding, efficiency of an enzyme to metabolize a drug.
• Metabolite Kinetics : to understand how drug deposition is impacted by hepatic clearance.Formation of drug metabolite is an important part of patient care because metabolite can have therapeutic activity or be toxic.q