Pharma - Berto - L6 part 2

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Questions and Answers

What is the primary method to determine the absolute bioavailability of a drug?

Comparing it with an oral dose of the drug

Assessing the speed of drug metabolism

Comparing it with an intravenous dose of the drug in the same subject (correct)

Evaluating the drug's therapeutic index

Which statement accurately describes bioavailability?

It is a qualitative measure of the drug's application in various settings.

It refers only to the speed at which a drug is eliminated from the body.

It solely represents the total amount of drug administered.

It indicates the degree and speed at which a drug reaches unchanged systemic circulation. (correct)

What would indicate a steady state plasma concentration (Cp ss) during repetitive administration of a drug?

The drug is only administered once.

The dosage of the drug is significantly reduced.

The drug concentration continuously increases over time.

The concentration of the drug elimination equals the concentration of the drug administered. (correct)

What aspect is essential for two drugs to be considered bioequivalent?

Their AUC values must be equivalent, regardless of their Cmax and Tmax. Signup and view all the answers

How does continuous infusion impact the plasma concentration (Cp) of a drug?

It increases due to constant administration of the drug. Signup and view all the answers

Which of the following conditions could increase drug concentration at steady state (Cp ss)?

Having liver or kidney diseases which decrease drug clearance. Signup and view all the answers

What is meant by the term Cmax in pharmacokinetics?

The maximum concentration of the drug reached in the bloodstream. Signup and view all the answers

What does Tmax represent in the context of drug administration?

The time it takes to reach maximum plasma concentration. Signup and view all the answers

What does the term 'relative bioavailability' refer to?

Comparing the bioavailability of different pharmaceutical preparations of the same drug. Signup and view all the answers

What happens when the interval between doses is too high in a repetitive administration therapy?

There won't be an accumulation between subsequent doses. Signup and view all the answers

What is the relationship between the dose and the time required to reach the plateau in drug therapy?

The dose does not affect the time necessary to reach the plateau. Signup and view all the answers

What is the likely consequence of a shorter interval between doses during drug administration?

Increased fluctuations between maximum and minimum drug concentrations. Signup and view all the answers

What does the maintenance dose formula (Maintenance dose = Cl × Cp ss × T) indicate?

It maintains drug levels at steady state based on clearance and desired concentration. Signup and view all the answers

Which of the following correctly defines the plateau phase in drug administration?

It occurs when the drug elimination equals the dosage administration. Signup and view all the answers

How does the volume of distribution (Vd) influence the height of the plateau concentration?

Lower Vd results in a lower plateau concentration. Signup and view all the answers

What characterizes the accumulation phase of a drug?

It is marked by exponential growth in drug levels until plateau is achieved. Signup and view all the answers

What is the primary purpose of administering a loading dose?

To reach the desired drug concentration quickly when the accumulation phase is too long. Signup and view all the answers

What best describes adverse effects associated with drug use?

They can be classified based on their frequency of occurrence. Signup and view all the answers

Which factor does NOT influence the size of the maintenance dose required?

Duration of acute therapy. Signup and view all the answers

Study Notes

Absolute Bioavailability

Absolute bioavailability (F) measures the fraction of a drug that reaches systemic circulation.
Determined by comparing AUC (Area Under Curve) of a drug administered orally versus intravenously.
An AUC ratio of 1 (or 100%) indicates complete absorption via intravenous administration.

Relative Bioavailability

Compares the bioavailability of different pharmaceutical preparations of the same drug.
Bioavailability assesses the speed and degree of unchanged drug reaching systemic circulation.
Bioequivalence exists when different formulations reach blood circulation at equal rates and extents.

Drug Preparations and Bioequivalence

Different pharmaceutical preparations can show varied maximum concentration (Cmax) and time to reach maximum concentration (Tmax).
Bioequivalence can occur even with different Cmax and Tmax as long as AUC values are equivalent.
Generic drugs must have similar bioavailability as their brand-name counterparts.

Repetitive Administration and Steady State

Goal of therapy: maintain effective drug concentration between minimum toxic and minimum efficacy concentrations.
Steady state plasma concentration (Cp ss) requires controlled dosing.
Continuous infusion achieves a constant drug concentration over time, balancing drug elimination and administration.

Factors Affecting Steady State

Infusion speed directly influences plasma concentration.
Liver or kidney diseases can increase plasma concentration due to lower clearance rates.
Dosing intervals impact drug accumulation; longer intervals reduce accumulation, while shorter intervals can lead to higher concentrations.

Accumulation Phase and Half-life

Reaching the plateau phase (steady state) typically occurs after approximately 5 half-lives of the drug.
The average plasma concentration at steady state depends on dosing frequency.
AUC at equilibrium equals Cp ss multiplied by the dosing interval.

Maintenance and Loading Dose

Maintenance dose keeps the drug concentration at steady state, calculated using clearance (Cl) and desired Cp ss.
Dose influences the height of the plateau but not the time to achieve it.
The closer the administration intervals, the smaller the fluctuations in drug concentration at steady state.
Loading dose is utilized when reaching steady state takes too long, based on volume of distribution (Vd) and desired plasma concentration (Cp ss).

Adverse Effects of Drugs

Adverse effects are harmful and unwanted outcomes from drug usage.
Classified by frequency of occurrence, ranging from common (more than 1/100) to rare (less than 1/10,000).

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Description

Explore the concept of absolute bioavailability and how it is calculated by comparing the pharmacokinetics of a drug administered via different routes. This quiz will cover both absolute and relative bioavailability, providing insights into drug absorption in the body.