Pharmacology Basics Quiz

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Questions and Answers

What is a primary disadvantage of intravenous parenteral administration?

Requires a trained professional for administration (correct)

Slower absorption compared to intramuscular injection

Higher risk of first-pass metabolism

Limited control over drug dosage

Why are drugs administered via the sublingual route more effective than oral administration?

They require food for enhanced absorption

They are less sensitive to gastric acid degradation

They bypass the intestinal and hepatic metabolic processes (correct)

They are absorbed more slowly in the bloodstream

Which statement best describes the absorption characteristics of intramuscular injections?

They are absorbed more rapidly than intravenous injections

Absorption is consistent regardless of the drug's formulation

Drugs in aqueous solutions are absorbed quickly (correct)

They provide immediate access to systemic circulation

What occurs to insulin when taken orally?

It is destroyed by gastric acid and enzymes Signup and view all the answers

What advantage does rectal administration have over oral administration?

It directly delivers drugs to the bloodstream without metabolic inactivation Signup and view all the answers

What limitation do unconscious patients impose on drug administration?

They may not be able to receive sublingual medications Signup and view all the answers

Which route of drug administration avoids both first-pass metabolism and gastric degradation?

Sublingual Signup and view all the answers

What is a disadvantage of parenteral drug administration compared to oral administration?

Requires careful dosing due to rapid onset of effects Signup and view all the answers

What term describes the study of the effects of drugs on behavior and the functioning of the nervous system?

Neuro- and psychopharmacology Signup and view all the answers

Which process is primarily involved in pharmacokinetics?

The body's absorption and elimination of drugs Signup and view all the answers

What is the main focus of pharmacogenomics?

Utilizing genomic technologies for drug discovery Signup and view all the answers

Which route of drug administration is described as the most commonly used?

Oral Signup and view all the answers

What does toxicology study primarily focus on?

The harmful effects and treatment of toxins Signup and view all the answers

Which of the following is NOT a focus of pharmacodynamics?

Effects of drugs in large populations Signup and view all the answers

What does the term 'ADME' stand for in pharmacokinetics?

Absorption, Distribution, Metabolism, Excretion Signup and view all the answers

Which aspect is NOT typically considered when determining the route of drug administration?

The patient's age Signup and view all the answers

What is the main factor driving passive absorption of a drug across the GI tract?

Concentration gradient Signup and view all the answers

Which of the following statements about active transport is true?

It can move drugs against the concentration gradient. Signup and view all the answers

How does pH affect weak acids and weak bases during drug absorption?

Weak acids are more permeable in their uncharged, protonated form. Signup and view all the answers

What does pKa indicate about a compound?

The strength of the interaction with a proton. Signup and view all the answers

At what pH level will a drug with a pKa of 5 be 50% protonated and 50% nonprotonated?

At pH 5 Signup and view all the answers

When a weak base loses a proton, which form penetrates through the cell membrane more effectively?

The uncharged form (B) Signup and view all the answers

Which of the following factors influences the relative concentrations of charged and uncharged forms of a drug?

The pH at the absorption site Signup and view all the answers

What is a key characteristic of the uncharged form of acidic drugs during absorption?

It enhances permeability through cell membranes. Signup and view all the answers

Which of the following describes Phase II drug metabolism?

Involves conjugation reactions to form polar compounds Signup and view all the answers

What is the most common conjugation reaction in drug metabolism?

Glucuronidation Signup and view all the answers

In drug elimination, which route is primarily responsible for the removal of drugs from the body?

Renal excretion into urine Signup and view all the answers

What distinguishes neonates regarding drug metabolism compared to adults?

Deficiency in conjugation systems Signup and view all the answers

What does the extraction ratio of a drug signify?

The ratio of the drug concentration exiting to entering the kidneys Signup and view all the answers

Which of the following processes is NOT part of renal elimination?

Excretion through bile ducts Signup and view all the answers

In first order kinetics, how does the concentration of the drug in plasma change over time?

It drops exponentially with time Signup and view all the answers

What factor is inversely related to the half-life of a drug?

Clearance Signup and view all the answers

How is the glomerular filtration rate (GFR) related to renal plasma flow (RPF)?

GFR is approximately 20% of RPF Signup and view all the answers

Which of the following is true regarding total body clearance (CLtotal)?

It is the sum of clearances from all drug-eliminating organs Signup and view all the answers

Which drug is known to undergo a Phase II reaction before a Phase I reaction?

Isoniazid Signup and view all the answers

What clinical situation might lead to an increased half-life of a drug?

Renal failure, affecting drug excretion Signup and view all the answers

Which factor determines how well blood is filtered by the kidneys?

Glomerular filtration rate (GFR) Signup and view all the answers

What may prolong the half-life of certain drugs in the body?

Increased enterohepatic circulation of drugs Signup and view all the answers

What characterizes first-order kinetics in drug metabolism?

A constant fraction of drug is metabolized per unit time. Signup and view all the answers

In which situation does zero-order kinetics occur during drug metabolism?

When the enzyme is saturated with free-drug concentration. Signup and view all the answers

How is total clearance (Cltotal) calculated using K and Vd?

Cltotal = Ke * Vd Signup and view all the answers

What is the role of the cytochrome P-450 system in drug metabolism?

It catalyzes phase I reactions that convert lipophilic drugs into more polar molecules. Signup and view all the answers

Which statement best describes the relationship between volume of distribution and half-life?

An increased volume of distribution leads to a prolonged half-life Signup and view all the answers

What effect do phase I reactions have on drug metabolism?

They may increase, decrease, or have no effect on pharmacologic activity. Signup and view all the answers

What happens to lipophilic drugs in the kidney?

They are readily reabsorbed due to their ability to cross cell membranes. Signup and view all the answers

What does the Michaelis-Menten constant (Km) signify in drug metabolism?

The substrate concentration at which the reaction rate is half of Vmax. Signup and view all the answers

Which statement about drug metabolism is true?

Phase I metabolism primarily involves the introduction of polar functional groups. Signup and view all the answers

What is the primary distinction between first-order and zero-order drug kinetics?

First-order kinetics are dependent on drug concentration while zero-order are not. Signup and view all the answers

Study Notes

General Pharmacology

Pharmacology is the study of how living organisms interact with chemicals that change normal biochemical function.
Pharmaceuticals are substances with medicinal properties.
A drug is a chemical substance used to treat, diagnose, or prevent diseases.
Pharmacology is subdivided into various branches including clinical pharmacology, neuro- and psychopharmacology, pharmacogenetics, pharmacogenomics, and pharmacoepidemiology.
Toxicology is the study of the harmful effects of drugs and toxins, and involves diagnosing and treating exposures.

Introduction

Pharmacology includes two main aspects: pharmacokinetics (what the body does to the drug, or ADME - Absorption, Distribution, Metabolism, and Excretion), and pharmacodynamics (what the drug does to the body, including the pharmacological action and mechanism).
Different routes of drug delivery have different properties for administration.

Routes of Drug Administration

The therapeutic objectives and the need for long-term administration or restriction of a drug to a specific site determine the best route of administration.
Enteral routes (oral, sublingual, and rectal) are common.
- Oral administration is the most common. Drugs are absorbed through the gastrointestinal tract and may encounter the liver (first-pass effect). Food can affect absorption.
- Sublingual administration avoids first-pass effect and allows direct absorption into the bloodstream.
- Rectal administration bypasses the liver to some extent.
Parenteral routes include intravenous (IV), intramuscular (IM), subcutaneous (SC), intradermal (ID), intraarticular, and intracardiac, are used for poorly absorbed drugs, agents that are unstable in the GI tract, unconscious patients, and for rapid onset of action.
- IV avoids first-pass metabolism and allows for rapid onset of action.
- IM administration involves drug injection into muscle, has a faster absorption when in aqueous solution versus depot preparations.
- SC involves injection under the skin, minimizing intravascular risks. Epinephrine is sometimes combined with the drug to restrict the absorption area, acting as a local vasoconstrictor to reduce removal.
Other routes include inhalation (e.g., anesthetics, bronchodilators) and intranasal (e.g., desmopressin).
Intrathecal/Intraventricular administration is used to directly introduce drugs into the cerebrospinal fluid.
Topical administration is used for local effects (e.g., creams, eye drops).
Transdermal administration delivers drugs through the skin using transdermal patches for sustained release.

Absorption of Drugs

Absorption is the transfer of a drug from the site of administration to the blood stream.
Factors like passive diffusion, active transport, pH, and drug properties influence rate and extent of absorption.
Passive diffusion is the driving force across a concentration gradient.
Active transport is energy dependent, and moves the drug against a concentration gradient.
The pH of the absorption site affects the degree of ionization of weak acids and bases. These forms of drugs have different permeability.
Physical factors of the absorption site like blood flow to the intestine is greater than stomach, which affects absorption rate.

Bioavailability

Bioavailability is the fraction of a drug that reaches the systemic circulation in its unchanged form.
Factors affecting bioavailability include the rate of absorption, first-pass metabolism, drug solubility, drug stability, and the nature of the drug formulation.
First-pass effect influences bioavailability greatly when drugs are administered orally.
Drug solubility matters: drugs must dissolve; if not they can't be absorbed.
Different drug forms can influence bioavailability.

Drug Distribution

Distribution is the movement of a drug from the bloodstream to the tissues.
Factors that determine distribution include blood flow to tissues, capillary permeability, drug binding to plasma proteins, and the drug's ability to cross membranes.
Blood-brain barrier restricts drugs.
Some drugs can bind with plasma proteins, thus slowing the distribution and action of the drug.

Volume of Distribution

Volume of distribution (Vd) is a theoretical volume that represents the apparent space where drug is distributed.
Vd varies based on the drug and patient factors.
Vd calculation includes the relationship between the dose and the concentration of the drug in the body.

Drug Metabolism

Metabolism is the enzymatic process of transforming the drug molecules.
Liver is the major site for drug metabolism. Other locations include the kidneys, intestines, and lungs.
Two main phase types for drug metabolism: - Phase I reactions involve the introduction or unmasking of polar functional groups to a drug to enhance its water-solubility to get rid of it. - Phase II reactions involve conjugations to further enhance drug solubility to be secreted from the body.
Kinetics of metabolism can have first order kinetics in low doses or zero order kinetics at high doses (when drug reactions are saturated).

Drug Elimination

Elimination refers to the removal of the drug from the body.
Renal elimination is the most important route of drug excretion, involving glomerular filtration, active tubular secretion, and passive tubular reabsorption.
Extraction ratio: the proportion of the drug extracted during passing through the kidney.
Factors affecting elimination rate include hepatic or biliary clearance or elimination, or extracorporeal dialysis in cases of renal failure.
Total body clearance is the sum of clearances from different organs of elimination,.

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Description

Test your knowledge on drug administration methods, their advantages and disadvantages, and key pharmacological concepts. This quiz covers various routes of drug delivery and their impacts on drug efficacy and metabolism. Perfect for students or professionals in the field of medicine and pharmacology.