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?

<p>It is destroyed by gastric acid and enzymes (D)</p> Signup and view all the answers

What advantage does rectal administration have over oral administration?

<p>It directly delivers drugs to the bloodstream without metabolic inactivation (A)</p> Signup and view all the answers

What limitation do unconscious patients impose on drug administration?

<p>They may not be able to receive sublingual medications (D)</p> Signup and view all the answers

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

<p>Sublingual (D)</p> Signup and view all the answers

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

<p>Requires careful dosing due to rapid onset of effects (C)</p> 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?

<p>Neuro- and psychopharmacology (B)</p> Signup and view all the answers

Which process is primarily involved in pharmacokinetics?

<p>The body's absorption and elimination of drugs (C)</p> Signup and view all the answers

What is the main focus of pharmacogenomics?

<p>Utilizing genomic technologies for drug discovery (A)</p> Signup and view all the answers

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

<p>Oral (A)</p> Signup and view all the answers

What does toxicology study primarily focus on?

<p>The harmful effects and treatment of toxins (B)</p> Signup and view all the answers

Which of the following is NOT a focus of pharmacodynamics?

<p>Effects of drugs in large populations (A)</p> Signup and view all the answers

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

<p>Absorption, Distribution, Metabolism, Excretion (D)</p> Signup and view all the answers

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

<p>The patient's age (C)</p> Signup and view all the answers

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

<p>Concentration gradient (C)</p> Signup and view all the answers

Which of the following statements about active transport is true?

<p>It can move drugs against the concentration gradient. (C)</p> Signup and view all the answers

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

<p>Weak acids are more permeable in their uncharged, protonated form. (D)</p> Signup and view all the answers

What does pKa indicate about a compound?

<p>The strength of the interaction with a proton. (C)</p> Signup and view all the answers

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

<p>At pH 5 (B)</p> Signup and view all the answers

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

<p>The uncharged form (B) (A)</p> Signup and view all the answers

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

<p>The pH at the absorption site (B)</p> Signup and view all the answers

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

<p>It enhances permeability through cell membranes. (C)</p> Signup and view all the answers

Which of the following describes Phase II drug metabolism?

<p>Involves conjugation reactions to form polar compounds (D)</p> Signup and view all the answers

What is the most common conjugation reaction in drug metabolism?

<p>Glucuronidation (B)</p> Signup and view all the answers

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

<p>Renal excretion into urine (D)</p> Signup and view all the answers

What distinguishes neonates regarding drug metabolism compared to adults?

<p>Deficiency in conjugation systems (B)</p> Signup and view all the answers

What does the extraction ratio of a drug signify?

<p>The ratio of the drug concentration exiting to entering the kidneys (C)</p> Signup and view all the answers

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

<p>Excretion through bile ducts (A)</p> Signup and view all the answers

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

<p>It drops exponentially with time (A)</p> Signup and view all the answers

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

<p>Clearance (B)</p> Signup and view all the answers

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

<p>GFR is approximately 20% of RPF (C)</p> Signup and view all the answers

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

<p>It is the sum of clearances from all drug-eliminating organs (B)</p> Signup and view all the answers

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

<p>Isoniazid (C)</p> Signup and view all the answers

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

<p>Renal failure, affecting drug excretion (B)</p> Signup and view all the answers

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

<p>Glomerular filtration rate (GFR) (C)</p> Signup and view all the answers

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

<p>Increased enterohepatic circulation of drugs (D)</p> Signup and view all the answers

What characterizes first-order kinetics in drug metabolism?

<p>A constant fraction of drug is metabolized per unit time. (D)</p> Signup and view all the answers

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

<p>When the enzyme is saturated with free-drug concentration. (C)</p> Signup and view all the answers

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

<p>Cltotal = Ke * Vd (D)</p> Signup and view all the answers

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

<p>It catalyzes phase I reactions that convert lipophilic drugs into more polar molecules. (A)</p> Signup and view all the answers

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

<p>An increased volume of distribution leads to a prolonged half-life (C)</p> Signup and view all the answers

What effect do phase I reactions have on drug metabolism?

<p>They may increase, decrease, or have no effect on pharmacologic activity. (C)</p> Signup and view all the answers

What happens to lipophilic drugs in the kidney?

<p>They are readily reabsorbed due to their ability to cross cell membranes. (C)</p> Signup and view all the answers

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

<p>The substrate concentration at which the reaction rate is half of Vmax. (A)</p> Signup and view all the answers

Which statement about drug metabolism is true?

<p>Phase I metabolism primarily involves the introduction of polar functional groups. (B)</p> Signup and view all the answers

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

<p>First-order kinetics are dependent on drug concentration while zero-order are not. (A)</p> Signup and view all the answers

Flashcards

Pharmacology

The study of how living organisms interact with foreign chemicals that change normal body processes.

Drug

A substance used to treat, diagnose, or prevent a disease.

Pharmacokinetics

What the body does to a drug (absorption, distribution, metabolism, excretion).

Pharmacodynamics

What a drug does to the body.

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Oral administration

Giving a drug by mouth (most common).

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Enteral route

Drug administration using the digestive system.

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ADME

Absorption, distribution, metabolism, and excretion.

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Routes of drug administration

Different ways to give medicine to a patient.

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First-pass metabolism

The process where a significant portion of an orally administered drug is metabolized by the liver, reducing its effectiveness.

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Sublingual administration

Drug delivery under the tongue, allowing direct absorption into the bloodstream, bypassing liver metabolism.

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Rectal administration

Drug delivery through the rectum, minimizing liver metabolism as half of the blood flow bypasses the liver.

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Parenteral administration

Drug delivery by injection, bypassing the digestive system, often used for rapidly acting drugs or those poorly absorbed by the gut.

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Intravenous (IV) injection

Drug injection directly into a vein, providing the fastest delivery and highest blood concentration.

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Intramuscular (IM) injection

Drug injection into a muscle, resulting in a faster absorption rate than subcutaneous injection and slower than IV.

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Drug efficacy

The ability of a drug to produce a desired effect.

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First-pass effect

The reduction in the bioavailability of a drug due to metabolism in the liver after oral ingestion.

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Transdermal route

A drug delivery method using a patch that adheres to the skin, allowing the drug to slowly permeate through the skin into the bloodstream. This route is ideal for sustained drug delivery over a longer period.

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Absorption

The process of a drug moving from its administration site into the bloodstream.

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Passive diffusion

A process where a drug moves from a region of high concentration to a region of low concentration, without requiring energy or carrier molecules.

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Active transport

A process that uses energy to move a drug against its concentration gradient, meaning from a low concentration area to a high concentration area. This involves specialized carrier proteins.

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pH effect on absorption

The ionization state of a drug (charged or uncharged) is affected by the pH of the environment. Only the uncharged form of a drug can easily pass through cell membranes.

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pKa

A measure of the strength of a weak acid or base. It represents the pH at which 50% of the drug is protonated (charged) and 50% is unprotonated (uncharged).

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Lower pKa

Indicates a stronger acid. A drug with a lower pKa will be predominantly uncharged at a relatively low pH.

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Why is pKa important?

Understanding pKa helps determine the drug's absorption characteristics. It predicts which form of the drug, charged or uncharged, will be more prevalent at a specific pH, influencing its ability to cross cell membranes.

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Phase I Metabolism

The first step in drug metabolism where the drug is modified by oxidation, reduction, or hydrolysis. These reactions often make the drug more water-soluble, but not always.

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Phase II Metabolism

The second step in drug metabolism where the drug is conjugated with an endogenous substrate like glucuronic acid, making it more water-soluble and easier to excrete.

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Conjugation

The process of attaching a molecule (like glucuronic acid) to a drug during Phase II metabolism, making it more water-soluble and easier to excrete.

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Glomerular Filtration

The process by which the kidneys filter blood, removing waste products and excess fluids. It is the first step in renal elimination of drugs.

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Tubular Secretion

The active transport of drugs and other molecules from the blood into the renal tubules for eventual excretion in urine.

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Tubular Reabsorption

The passive movement of drugs from the renal tubules back into the blood.

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Drug Elimination

The process by which a drug is removed from the body, primarily through the kidneys, but also via the bile, intestines, lungs, or milk in nursing mothers.

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Extracorporeal Dialysis

A procedure used to remove small molecules like drugs from the blood of patients with kidney failure.

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First-order kinetics

A constant FRACTION of drug is metabolized per unit time. This occurs when drug concentration is much lower than the Michaelis constant (Km).

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Zero-order kinetics

A constant AMOUNT of drug is metabolized per unit time. This occurs when drug concentration is much higher than the Michaelis constant (Km).

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What happens to drug metabolism when the drug concentration is much less than Km?

First-order kinetics apply, meaning a constant fraction of the drug is metabolized per unit time.

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What happens to drug metabolism when the drug concentration is much greater than Km?

Zero-order kinetics apply, meaning a constant amount of drug is metabolized per unit time.

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Phase I reactions

These introduce or unmask a polar functional group (like -OH or -NH2) to make lipophilic drugs more polar.

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P-450 system

A group of enzymes primarily responsible for catalyzing Phase I reactions, often involved in drug metabolism.

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Why is drug metabolism important?

Lipophilic drugs are easily reabsorbed in the kidney, making excretion difficult. Metabolism converts them to more polar (hydrophilic) substances, facilitating excretion.

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What's the main difference between Phase I and Phase II reactions?

Phase I introduces or unmasks polar groups, while Phase II adds a large molecule to increase polarity and water solubility.

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Extraction Ratio

The ratio of the drug concentration exiting the kidneys (C2) to the concentration entering the kidneys (C1).

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Half-life

The time it takes for the concentration of a drug in the body to decrease by half.

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Total Body Clearance

The overall rate at which a drug is removed from the body, considering all organs involved in elimination.

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Steady state equation

An equation that relates the total body clearance (Cltotal) to the elimination rate constant (ke) and volume of distribution (Vd).

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Volume of Distribution

The apparent volume in which a drug is distributed in the body. It reflects how much drug is present in the plasma compared to the rest of the body.

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Drug Half-life and Volume of Distribution

The half-life of a drug is inversely proportional to its clearance and directly proportional to its volume of distribution. This means that a larger volume of distribution increases the drug's half-life.

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Drug Half-life and Clinical Situations

When a patient has a condition that alters the drug's half-life, adjustments in dosage may be required.

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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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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.

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