Pharma - Berto - L5 part 1

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Questions and Answers

What is the primary disadvantage of the oral route of administration?

Invasive nature of administration

Slow onset of action

Reduced bioavailability due to first-pass metabolism (correct)

High peak concentration achieved

Which parenteral route is particularly important for diabetic patients?

Subcutaneous route (correct)

Intramuscular route

Inhalatory route

Intravenous route

What is a significant effect of intravenous drug administration compared to other routes?

Immediate peak concentration followed by rapid decline (correct)

Higher risk of first-pass metabolism

Prolonged therapeutic effect

Lower toxicity risk overall

Why is it essential to control the administration rate of intravenous drugs?

To avoid damage to blood and tissues Signup and view all the answers

How can the cutaneous route of administration be characterized?

Important for diagnostic purposes Signup and view all the answers

What factor drastically affects the absorption through inhalatory routes?

Particle size of the drug Signup and view all the answers

What distinguishes transmucosal routes from other routes of administration?

Efficient for local therapeutic effects Signup and view all the answers

What is implied about elimination curves across different routes of administration?

They are consistent among all the routes Signup and view all the answers

Which feature of the drug significantly influences its administration route?

Partition coefficient Signup and view all the answers

What is one of the main benefits of using enteral routes for medication delivery?

Ease of self-administration Signup and view all the answers

What best describes the role of the partition coefficient (Kp) in drug distribution?

It represents the ratio of drug concentration in the tissue to that in the plasma. Signup and view all the answers

Which factor does NOT influence the binding of drugs to plasma proteins?

The molecular weight of the drug. Signup and view all the answers

In what circumstance can the displacement of the bound fraction of drugs lead to toxic effects?

When drug concentration exceeds the binding capacity of plasma proteins. Signup and view all the answers

What is the primary purpose of drug metabolism in the body?

To facilitate the elimination of both drugs and endogenous substances. Signup and view all the answers

Which phase of drug distribution is characterized by the rapid transfer to highly perfused organs?

First phase of distribution. Signup and view all the answers

What happens to the apparent volume of distribution (Vd) if Kp is low?

It suggests the plasma concentration is higher than the tissue concentration. Signup and view all the answers

How do physiological factors impact plasma protein concentrations?

They can alter concentrations, affecting drug binding and actions. Signup and view all the answers

Which statement about highly lipophilic drugs is true?

They can accumulate in poorly perfused fat tissues due to their properties. Signup and view all the answers

Which process can lead to a slower decay of the free drug concentration in plasma?

Increased binding to plasma proteins. Signup and view all the answers

Which enzyme is primarily responsible for the metabolism of ethanol?

Alcohol dehydrogenase Signup and view all the answers

What type of enzymes are monoamine oxidases classified as?

Oxidoreductases Signup and view all the answers

Where are the enzymes responsible for hydrolysis reactions predominantly located?

Endoplasmic reticulum Signup and view all the answers

Which neurotransmitters are significantly metabolized by monoamine oxidases?

Catecholamine and Serotonin Signup and view all the answers

What is the primary function of aldehyde dehydrogenase in the metabolism process?

Detoxification of acetaldehyde Signup and view all the answers

What do hydrolysis reactions primarily do to substrates?

Unmask functional groups Signup and view all the answers

Which enzyme is known for its role in the metabolism of purines?

Xanthine oxidase Signup and view all the answers

Which of the following is NOT a type of enzyme mentioned in the context of catalyzing hydrolysis reactions?

Dehydrogenases Signup and view all the answers

What type of enzyme is diamine oxidase categorized as?

Hydrolase Signup and view all the answers

Which of the following statements about alcohol and aldehyde dehydrogenase is correct?

They play roles in the cytoplasm of cells. Signup and view all the answers

What is one consequence of the metabolism of paracetamol at high doses?

It leads to the accumulation of parabenzoquinone in hepatocytes. Signup and view all the answers

Which of the following best describes phase I metabolic reactions?

They primarily involve oxidation, reduction, and hydrolysis processes. Signup and view all the answers

What role do cytochrome P450 enzymes play in drug metabolism?

They are the first mechanism to detoxify xenobiotic substances. Signup and view all the answers

Which is a function of NADPH reductase in the cytochrome P450 complex?

It receives electrons and reduces cytochrome P450. Signup and view all the answers

What type of reactions predominantly occur during phase I metabolism?

Oxidation and reduction reactions involving functional group modifications. Signup and view all the answers

Which metabolite is produced by the reduction of azo compounds by cytochrome P450?

Sulphonamide Signup and view all the answers

Which cytochrome P450 isoform is most abundantly expressed in the liver?

CYP3A4 Signup and view all the answers

What happens to glutathione levels at high doses of paracetamol?

They become depleted, leading to hepatotoxicity. Signup and view all the answers

What is one of the main functions of Phase II metabolic reactions?

To conjugate drug metabolites to enhance their excretion. Signup and view all the answers

How do cytochromes affect drug metabolism?

They can both activate prodrugs and inactivate active drugs. Signup and view all the answers

Study Notes

Routes of Administration

Administration routes are divided into enteral (oral, sublingual, rectal) and parenteral (intravenous, intramuscular, cutaneous, subcutaneous, inhalatory, transcutaneous, transmucosal).
Oral administration is most common but suffers from first-pass metabolism reducing bioavailability.
Sublingual and rectal routes can bypass first-pass metabolism, providing advantages.
Intravenous routes quickly achieve maximum drug concentration but require careful administration to avoid damage.
Intramuscular route, cutaneous route (for diagnostics), and subcutaneous route (for insulin delivery) are also important parenteral methods.
Inhalation can elicit systemic or local effects, influenced by particle size and delivery.

Absorption and Effects

Different administration routes lead to varying peak concentrations and therapeutic effects.
Intravenous administration results in rapid peak concentration followed by quick decline, increasing risk of toxicity.
Oral and intramuscular routes produce lower peak concentrations, allowing for prolonged therapeutic effects.
Elimination kinetics are similar across routes; differences lie in initial peak and duration of drug effect.

Distribution Factors

Distribution occurs among three fluid compartments: plasma, extracellular, intracellular.
Influential factors in drug distribution include blood flow, partition coefficient, and protein binding.
Plasma proteins, primarily albumin (acidic drugs) and alpha-1-acid glycoprotein (basic drugs), are crucial for drug binding.
Factors such as age and diseases can modify plasma protein concentrations, influencing drug actions.

Volume of Distribution

Apparent volume of distribution (Vd) indicates how a drug is distributed across body compartments, not reflecting real anatomical volumes.
High Kp (tissue concentration/plasma concentration) suggests greater drug presence in tissues; low Kp indicates the opposite.

Drug Metabolism

Drug metabolism detoxifies substances, primarily occurring in the liver through two phases: functionalization (Phase I) and conjugation (Phase II).
Phase I reactions can activate or inactivate drugs through oxidation, reduction, and hydrolysis.
Cytochrome P450 enzymes play a vital role in drug oxidation; CYP3A4 is notable for metabolizing various substances.
Phase II includes conjugation reactions, which usually convert drugs to more hydrophilic forms for easier elimination.

Toxic Metabolites

Metabolism can yield toxic metabolites; paracetamol is an example that can cause hepatotoxicity due to a reactive metabolite when overdosed, requiring antidote acetylcysteine.

Cytochrome P450 System

Cytochrome P450 complex is essential for drug metabolism, comprising multiple isoenzymes with a significant presence in the liver.
Important isoforms for drug metabolism include CYP3A4, CYP2D6, and CYP2C9.
Cytochrome P450 catalyzes reactions in a series of steps involving substrate interaction and electron transfer from NADPH.

Hydrolysis and Other Reactions

Hydrolysis reactions, catalyzed by enzymes like esterases, unmask functional groups for Phase II processing.
Non-cytochrome dependent oxidative reactions involve soluble enzymes in the cytoplasm for metabolism of certain substances, such as alcohol.

Summary

Understanding the pharmacokinetics of drug administration (routes, absorption, distribution, metabolism) is crucial for effective therapeutic interventions and minimizing adverse effects.

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Description

This quiz focuses on the advantages and disadvantages of various routes of administration in pharmacology, specifically comparing enteral and parenteral methods. It highlights the oral route's commonality and its significant drawback related to bioavailability due to first-pass metabolism. Prepare to test your understanding of these crucial concepts.