Biopharmaceutics/Pharmacokinetics Lecture 1

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Questions and Answers

Which phase directly precedes the pharmacokinetic phase?

Drug-target interaction phase

Pharmacodynamic phase

Pharmacological availability phase

Pharmaceutical phase (correct)

Which of the following best describes the main focus of biopharmaceutics?

The measurement of drug concentrations in biological fluids.

The correlation between a drug's physicochemical properties and its biological effects. (correct)

The investigation of how drugs are absorbed, distributed, metabolized, and excreted.

The study of drug-target interactions at the molecular level.

According to the content, what is an important aspect of the pharmaceutical phase?

Disintegration and Dissolution (correct)

Drug-receptor binding

Metabolism of the drug

Drug excretion from the body

Which of these is NOT explicitly identified as a factor influenced by biopharmaceutics?

Drug binding at the receptor (A) Signup and view all the answers

In the context of the chart presented, which process directly follows 'Pharmaceutical Availability'?

Absorption, Distribution, Metabolism, Excretion (D) Signup and view all the answers

Which of these best describes the function of toxicokinetics?

To apply pharmacokinetic principles to interpret toxicity data and extrapolate to humans. (A) Signup and view all the answers

What is primarily being analyzed when studying pharmacodynamics?

The relationship between drug concentration at the site of action and the pharmacologic response. (D) Signup and view all the answers

Which of the options constitutes a non-invasive method for obtaining samples for drug concentration assays?

Saliva (D) Signup and view all the answers

What does 'non-linear pharmacokinetics' at toxic doses most likely involve?

Saturation of enzymes and other molecules involved in drug processes, such as metabolism (B) Signup and view all the answers

Which analytical method is best suited for separating a drug from other substances in a biological sample?

Chromatography, such as HPLC (D) Signup and view all the answers

Which factor is NOT typically considered when evaluating formulation properties relevant to systemic absorption?

Patient's age and gender (B) Signup and view all the answers

The term 'kinetikos', as it relates to pharmacokinetics, primarily refers to the:

Motion or movement of the drug (D) Signup and view all the answers

In the context of pharmacokinetic parameters, what is the primary relationship between the rate constant for absorption and drug amount in the body?

The rate constant influences the rate at which drug enters the body, thus affecting the amount of drug (B) Signup and view all the answers

Which of these best describes a key focus of the experimental aspects of pharmacokinetics?

Developing assays for drugs and their metabolites (D) Signup and view all the answers

What is the primary goal of developing models in the theoretical aspects of pharmacokinetics?

Predicting drug disposition following administration (C) Signup and view all the answers

Therapeutic drug monitoring (TDM) is MOST critical for drugs that have a:

Narrow therapeutic index (D) Signup and view all the answers

Population pharmacokinetics focuses on studying variability in drug response due to:

Age, gender, and ethnic factors (B) Signup and view all the answers

Which of the following is the BEST description of how the different aspects of pharmacokinetics are interconnected?

Experimental data informs theoretical modeling, which then guides clinical applications. (C) Signup and view all the answers

What does the term supernatant refer to in the context of blood samples?

The liquid portion of blood obtained after centrifuging. (D) Signup and view all the answers

Which blood component is obtained after centrifuging coagulated whole blood?

Serum (D) Signup and view all the answers

What does the area under the curve (AUC) in a plasma concentration-time graph represent?

Total drug exposure over time (D) Signup and view all the answers

What is a primary use of the AUC in drug studies?

Evaluation of toxicity and bioequivalence (A) Signup and view all the answers

Why might whole blood samples be preferred over plasma or serum samples for drug assays in research settings?

Whole blood contains all drug-related components, including bound cellular elements within. (A) Signup and view all the answers

According to the provided text, which biological specimens are explicitly mentioned for drug concentration assays?

Blood, serum and plasma (D) Signup and view all the answers

Besides plasma concentrations, what other information is needed to make the most informed decisions about drug dosing?

Other relevant pharmacokinetic information (C) Signup and view all the answers

What is a key difference between using plasma versus serum in drug concentration assays?

Plasma is obtained from non-coagulated blood unlike serum. (C) Signup and view all the answers

Why is urine concentration an indirect indication of systemic drug concentration?

Because it represents the cumulative excretion of the drug over time through the kidneys. (B) Signup and view all the answers

What does fecal drug concentration primarily indicate?

The degree of drug systemic absorption after oral administration or biliary excretion (D) Signup and view all the answers

Why are saliva concentrations useful in drug monitoring?

They approximate free drug concentrations in plasma because free drug can passively diffuse into saliva. (A) Signup and view all the answers

What is a key function of a pharmacokinetic model?

To use mathematical equations to optimize dosage regimens for individual patients. (A) Signup and view all the answers

Which is NOT a factor that a pharmacokinetic parameter's value depends on?

The individual's genetic predispositions. (C) Signup and view all the answers

What is the significance of the pharmacokinetic parameter 'ke'?

It reflects the rate at which a drug's concentration decreases. (D) Signup and view all the answers

What does the pharmacokinetic parameter t1/2 represent?

The time needed for half of the drug to be eliminated from the body. (A) Signup and view all the answers

What is the role of INR measurement in patients taking anti-coagulants?

It measures the blood's ability to clot. (C) Signup and view all the answers

Which characteristic is unique to physiologically-based models when compared to compartment-based models?

Reliance on actual anatomical and physiological data. (D) Signup and view all the answers

In a mammillary model, what is the primary characteristic of the central compartment?

It includes the plasma and highly perfused tissues such as liver and kidney. (A) Signup and view all the answers

What is a key assumption of both mammillary and catenary compartment models?

They assume an open system with drug entry and exit. (A) Signup and view all the answers

Which of the following best explains how a catenary model differs from a mammillary model?

A catenary model involves a central compartment that is sequentially connected to multiple tissue compartments, unlike a mammillary model. (C) Signup and view all the answers

What is a ‘compartment’ in the context of pharmacokinetic compartment models?

A tissue or tissue group that shares similar blood flow and drug affinity. (A) Signup and view all the answers

In pharmacokinetic modeling, what is the primary purpose of using rate constants?

To describe drug movement into and out of a compartment. (B) Signup and view all the answers

What is a key limitation of using compartment-based models for extrapolation to different species?

Their Volume of Distribution (Vd) has a limited relationship to blood flow and volume. (D) Signup and view all the answers

In a one-compartment mammillary model following intravenous drug injection, where does drug elimination occur?

Directly from the central compartment. (D) Signup and view all the answers

Which type of model relies more on direct experimental data for parameters like blood flow and tissue volume?

Physiologically-based models (A) Signup and view all the answers

Which statement best reflects the impact of pathophysiological conditions on pharmacokinetic models?

Both physiological and compartment models are influenced by pathophysiological conditions through data modification. (B) Signup and view all the answers

Study Notes

Course Information

Course title: Biopharmaceutics/Pharmacokinetics
Course code: PSW 313
Instructor: Dr. G. Acquaah-Mensah
Lecture 1: Introduction to Biopharmaceutics and Pharmacokinetics

Course Objectives

Identify the place of pharmacokinetics in pharmacotherapy
Define terms related to pharmacokinetics, biopharmaceutics, and pharmacodynamics
Discuss various methods for analyzing biological samples
Explain models used in pharmacokinetics
Distinguish between different model types used in pharmacokinetics

Overview of Biopharmaceutics and Pharmacokinetics

Biopharmaceutics: The study of the relationship between the nature and intensity of biological effects and the physicochemical properties of a drug, also includes pharmacokinetics as a branch
Some key factors of interest in biopharmaceutics include: drug stability, drug release/dissolution rate-product, release rate-absorption site, and systemic absorption
Specific formulation properties of interest include: dosage form type, pharmaceutical processes utilized in preparation, presence or absence of excipients, physical state, particle size and surface area, and chemical nature (e.g., salt, complex, ester)
Pharmacokinetics: The study of how the body handles/processes a drug, including drug absorption, distribution, metabolism, and excretion. It is also involved in drug administration, the time-course of distribution, and concentrations attained in different regions of the body
An important concept: the relationship between drug concentration and drug response. This relationship is crucial in determining therapeutic and toxic effects.

Parameters of Interest

Amount of drug administered
Rate constant for absorption
Amount of drug in the body
Rate constant for elimination
Amount of drug eliminated

Pharmacokinetics - Experimental Aspects

Biologic sampling techniques development
Assay methods for drugs and metabolites development
Data collection and manipulation techniques development

Pharmacokinetics - Theoretical Aspects

Drug disposition models after administration
Classical pharmacokinetics: model development and parameter estimation (e.g., equations for volume distribution, clearance)

Pharmacokinetics - Clinical Aspects

Patient-specific considerations for drug dosing
Optimized dosing strategies
Therapeutic drug monitoring (TDM) for drugs with narrow therapeutic indices
Population pharmacokinetics (age, gender, ethnicity, genetics)

Toxicokinetics

Applies pharmacokinetic principles to toxicology
Interprets pre-clinical toxicity data and extrapolates to humans
Non-linear pharmacokinetics at toxic doses (e.g., enzyme saturation)

Pharmacodynamics

Relationship between drug concentration at the site of action and the resulting pharmacologic response
Describes how the drug affects the body

Drug Concentration Assays

Biological specimens: Blood, plasma, serum, tissue, other body fluids and urine concentrations
Methods used to obtain these specimens (e.g., invasive vs non-invasive)
Assay types: Chromatography (HPLC), Immunoassays (e.g., fluorescence), Radioactive assays (e.g., TCA-RA), Mass Spectroscopy
Use of data obtained from drug concentration assays to analyze drug dosing outcomes, metabolite formation, and drug transport.

Plasma Concentration-Time Course

AUC (Area Under the Curve): A measure of the total drug exposure in a patient
AUC is useful in toxicity profile and bioequivalence studies
Factors influencing plasma concentration-time curves (pharmacokinetic and pharmacodynamic factors)

Drug Concentration Assays - Additional Information

Plasma concentrations: optimization of drug dosage, further investigation of the relevant pharmacokinetic factors, and pharmacodynamic response (e.g., INR for anticoagulants and ECG for cardiotonic drugs.)
Tissue concentrations (e.g., biopsies and disadvantages)
Urine and Fecal concentrations (e.g., indirect indication of systemic concentration, lack of absorption post-oral administration)
Saliva concentrations ( e.g., approximating free drug in plasma)

Pharmacokinetic Models - Introduction

Model types: Physiologically-based models, empirical (compartmental models))

Pharmacokinetic Models - Physiologic Models

Based on actual anatomical and physiological data
Blood flow and drug affinity
Tissue volume considerations
Examples of application: blood flow models or perfusion models

Pharmacokinetic Models - Compartment Models

Compartments: tissues or tissue groups with similar blood flow and drug affinity
Categories: Mammillary Model, Two-compartment system
Types: Linear assumptions; rate constants; open systems; estimates for concentrations in other compartments

Comparison of Physiologic and Compartment Models

Contrast of predictive capabilities in different scenarios and conditions, and when using animal data for human estimations (e.g., extrapolations

Model Types Contrasts

Physiologic vs. Compartmental Models - characteristics and comparisons. (e.g., data requirements, extrapolations)

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Description

Test your understanding of the introduction to biopharmaceutics and pharmacokinetics. This quiz covers key concepts such as the relationship between drug properties and biological effects, as well as various methods for analyzing biological samples. Explore models and definitions commonly used in pharmacotherapy.