Pharmacology Quiz: Key Concepts

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Questions and Answers

What does pharmacodynamics primarily focus on?

The distribution of drugs in large populations

The adverse effects of drugs

The effects of drugs on the body (correct)

The absorption of drugs in the body

Which of the following best describes pharmacogenomics?

The effects of drugs on nervous system function

The use of genomic technologies in drug discovery (correct)

The application of genetic testing for therapeutic purposes

The study of drug effects in population studies

Which component is NOT part of pharmacokinetics?

Excretion

Absorption

Pharmacological actions (correct)

Distribution

The enteral route of drug administration commonly includes which method?

Oral intake Signup and view all the answers

What is the main study focus of toxicology?

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

Which aspect does pharmacogenetics specifically address?

Clinical testing of genetic factors for therapy Signup and view all the answers

Why might a drug's route of administration be chosen specific to its properties?

To achieve optimal therapeutic outcomes Signup and view all the answers

The study of pharmacoeconomics is primarily concerned with which of the following?

The cost-effectiveness of drug therapies Signup and view all the answers

What is a characteristic benefit of subcutaneous (SC) injections?

They minimize risks associated with intravascular injection. Signup and view all the answers

What is the typical volume for an intradermal injection?

0.1 ml Signup and view all the answers

What is the purpose of epinephrine when combined with a drug in a subcutaneous injection?

To localize the drug's effects. Signup and view all the answers

Inhalation as a route of drug administration primarily relies on which feature of the lungs?

Their large surface area. Signup and view all the answers

Which route of administration is used to introduce drugs directly into the cerebrospinal fluid?

Intrathecal/lntraventricular Signup and view all the answers

What is the primary use of topical drug administration?

To provide a local effect of the drug. Signup and view all the answers

Which of the following drugs is commonly administered intranasally?

Desmopressin Signup and view all the answers

What is the main difference between transdermal and topical drug administration?

Transdermal is only for systemic effects, while topical is for local. Signup and view all the answers

Why are extremely hydrophobic drugs poorly absorbed in the body?

They cannot dissolve in aqueous body fluids. Signup and view all the answers

What percentage of body weight is approximately attributed to extracellular fluid in a 70-kg individual?

20% Signup and view all the answers

Which drug is known to be unstable in the gastric contents?

Penicillin G Signup and view all the answers

Which of the following drugs would likely have a larger volume of distribution (Vd)?

A hydrophobic drug that can cross cell membranes Signup and view all the answers

What factor unrelated to drug chemistry can influence drug absorption?

Particle size of the drug formulation Signup and view all the answers

If 25 mg of a drug is administered and the plasma concentration is 1.0 mg/L, what is the volume of distribution (Vd)?

25 L Signup and view all the answers

What does bioequivalence between two drugs imply?

They show comparable bioavailability and peak concentration times. Signup and view all the answers

What happens during the rapid distribution phase of drug distribution?

The drug is transferred from plasma to interstitium Signup and view all the answers

Which organ typically receives the greatest blood flow from cardiac output?

Liver Signup and view all the answers

Which type of drug is likely to distribute into both the extracellular fluid and the intracellular fluid?

Hydrophobic drug with low molecular weight Signup and view all the answers

What factor influences capillary permeability?

Chemical nature of the drug Signup and view all the answers

What is the primary determinant of a drug's volume of distribution (Vd)?

The drug's molecular weight and hydrophilicity Signup and view all the answers

Which of the following statements about therapeutic equivalence is true?

Therapeutic equivalence requires bioequivalence and pharmaceutical equivalence. Signup and view all the answers

Which factor related to drug formulation could slow down dissolution and absorption?

Crystallization of the drug Signup and view all the answers

How does the presence of elimination affect the observed plasma concentration versus time curve for a drug?

It exhibits two phases: distribution and elimination Signup and view all the answers

What is the typical volume of distribution for hydrophilic drugs in a 70-kg individual?

14 L Signup and view all the answers

What factor significantly influences the absorption of a drug at the intestine compared to the stomach?

Blood flow to the absorption site Signup and view all the answers

How does the surface area of the intestine contribute to drug absorption?

It is rich in microvilli, providing a larger surface area for absorption Signup and view all the answers

What effect does severe diarrhea have on drug absorption?

It reduces contact time with the absorption surface, leading to poor absorption Signup and view all the answers

What is bioavailability?

The fraction of the administered drug that reaches systemic circulation in an unchanged form Signup and view all the answers

What is the main reason for the first-pass hepatic metabolism affecting bioavailability?

It metabolizes drugs before they reach systemic circulation, reducing unchanged drug levels Signup and view all the answers

Which characteristic of a drug affects its permeability across lipid-rich cell membranes?

Hydrophilicity of the drug Signup and view all the answers

In a bioavailability study, what is an important metric used to compare drug levels from different administration routes?

Area under the curve (AUC) Signup and view all the answers

How does taking a drug with a meal generally affect its absorption?

It slows gastric emptying and dilutes the drug, leading to slower absorption Signup and view all the answers

What role does the proximal tubular secretion play in drug elimination?

It employs active transport systems for certain drug types. Signup and view all the answers

How does urine pH manipulation affect drug clearance?

It increases the ionization of weak acids for elimination. Signup and view all the answers

Which process describes the retention of certain drugs in the blood of premature infants?

Incompletely developed tubular secretory mechanism. Signup and view all the answers

What is the effect of alkalinizing the urine in a patient with phenobarbital overdose?

Increases drug ionization and decreases reabsorption. Signup and view all the answers

What happens when the concentration of a drug in the nephric lumen exceeds that of the perivascular space?

The drug diffuses out into systemic circulation if uncharged. Signup and view all the answers

Which statement describes the clearance of a drug in the renal system?

Clearance is a measure of the drug elimination rate scaled by plasma concentration. Signup and view all the answers

What is the extraction ratio in renal drug elimination?

The ratio of drug concentration in the plasma before and after kidney processing. Signup and view all the answers

What effect does acidification of urine have on weak bases?

Promotes their ionization and increases clearance. Signup and view all the answers

Study Notes

General Pharmacology

Pharmacology is the study of interactions between living organisms and external chemicals that alter natural biochemical processes.
If a substance has medicinal properties, it's considered a pharmaceutical.
A drug is a chemical substance used to treat, diagnose, or prevent (prophylaxis) diseases.
Pharmacology is a branch of chemical science practiced by pharmacologists.
It's subdivided into several subfields.
Clinical pharmacology examines the effects of medications on humans.
Neuro- and psychopharmacology studies the effects of medication on behavior and nervous system functioning.
Pharmacogenetics involves clinical testing of genes for therapeutic purposes.
Pharmacogenomics applies genomic technologies to new drug discovery.
Pharmacoepidemiology studies drug effects on large populations.
Toxicology examines the harmful effects of drugs, including adverse effects and treatments for toxin exposures.
Pharmacology can also be broken down into pharmacodynamics and pharmacokinetics.
Pharmacokinetics describes how the body processes a drug, encompassing absorption, distribution, metabolism, and excretion (ADME).
Pharmacodynamics details the effect of a drug on the body and its mechanism of action.

Routes of Drug Administration

Drug administration routes are selected based on therapeutic objectives, such as rapid onset or local action.
Enteral Routes:
- Oral: The most common route; drugs absorbed from the GI tract often go to the liver before general circulation. First-pass metabolism via the liver can significantly reduce drug efficacy. Food can affect absorption as well, some drugs are unabsorbable in the presence of food (insulin, penicillin).
- Sublingual: Placing medications under the tongue allows direct absorption into capillaries, bypassing the liver and intestines.
- Rectal: 50% of rectal drainage bypasses the liver, thus minimizing hepatic metabolism. This route is often used to administer antiemetics.
Parenteral Routes:
- Intravenous (IV): Direct injection into a vein, delivering drugs quickly into the blood, avoiding first-pass metabolism, and offering high drug concentration. High drug concentration, rapid onset, avoid gastric secretions and first pass metabolism are advantages; however, contamination and pain are disadvantages.
- Intramuscular (IM): Injection into muscle tissue; drugs in solution are absorbed quickly, while drugs in depot preparations (suspension form) have slower absorption. The absorption of a drug in solution is faster compared to the depot preparations. Pain is a disadvantage
- Subcutaneous (SC): Injection under the skin; absorption of drugs is generally slower than IM injections. Epinephrine is sometimes added to the solution to minimize the removal of the drug.
Other Routes:
- Inhalation: Absorption through the lungs is rapid due to the large surface area. Gasses like anesthetics and bronchodilators are often administered this way.
- Intranasal: Drugs delivered through the nasal passages, often as nasal sprays (e.g., desmopressin).
- Intrathecal/Intraventricular: Injection directly into cerebrospinal fluid, used for substances like methotrexate in specific cases.
- Topical: Application to the skin or other surfaces.
- Transdermal: Application via patches to achieve systemic effects, often used for sustained-release drugs like nitroglycerin.

Absorption of Drugs

Absorption is the movement of a drug from the site of administration into the bloodstream.
Absorption depends on drug transport across membranes.
Passive diffusion: drugs move down a concentration gradient (high to low).
Active transport: energy-dependent process; drugs move against the concentration gradient.
Effect of pH: Acidic drugs are better absorbed in acidic environments (uncharged), while basic drugs are better absorbed in alkaline environments.
Other factors influencing absorption include:
- Blood flow to the absorption site, since high blood flow means faster absorption. Surface area also plays a role (intestine has a much greater surface area compared to the stomach). The presence of food often slows gastric emptying and thus drug absorption. The solubility of the drug is a major factor, for example, very hydrophilic drugs are poorly absorbed. Sometimes, drugs are unstable in the gut's acidic environment, which could hinder absorption. Some drugs could interact with other compounds or substances to hinder absorption (e.g., other foods).

Bioavailability

Bioavailability is the fraction of an administered drug that reaches systemic circulation in unchanged form.
Determination of bioavailability involves comparing plasma drug levels after different administration routes (e.g., oral vs. intravenous). The area under the curve (AUC) is often used.
Factors influencing bioavailability include:
- First-pass hepatic metabolism, the degree of drug metabolism in the liver.
- Drug's solubility; very hydrophobic drugs are often poorly absorbed.
- Chemical instability, some drugs are liable to degrading/transforming before absorption, therefore, lower bioavailability.
- Nature of the drug formulation, particle size, salt form, crystal polymorphism; some of these can directly influence the absorption rate.
Bioequivalence means that two drugs have comparable bioavailability and similar peak blood concentrations.
Therapeutic equivalence means that two drugs have similar efficacy and safety, although they might have different pharmacokinetic profiles.

Drug Distribution

Distribution is the process of drug movement from the bloodstream into the tissues and other organs.
Factors affecting distribution include:
- Blood flow to tissues, capillary permeability. Capillary structure can affect drug distribution; some drugs can pass through the capillary slits in some places (e.g., brain). The lipid solubility of the drug can affect its distribution.
- Drug binding to plasma proteins, this can greatly affect distribution rate; bound drugs circulate without exerting effects.
Blood-brain barrier: the tightly connected endothelial cells in the brain limit the passage of many drugs into the brain; lipid soluble substances can readily cross.
Volume of distribution is a hypothetical volume that drug is distributed into to reflect its extent of distribution.

Drug Metabolism

Metabolism involves the biotransformation of drugs in the body, typically in the liver, but other tissues can also participate (e.g., intestinal walls).
Metabolism can either inactivate or activate a drug
Types of reactions:
- Phase I reactions (oxidation, reduction, hydrolysis) increase polarity, often to make them more readily eliminated.
- Phase II reactions (conjugation) usually produce more water-soluble compounds that are more readily excreted.
Rate of metabolism can be zero order or first order.
This system is mainly conducted by the P-450 system

Drug Elimination

Elimination is the removal of drugs from the body.
Renal elimination: Most important pathway, involving glomerular filtration, tubular secretion, and tubular reabsorption. Urine is important for removing the drug and thus it is the major route for elimination.
Other elimination methods include:
Hepatic (bile) elimination: Substances eliminated through bile, frequently metabolized in the liver first.
Pulmonary elimination: some drugs are exhaled in the form of gases.
Other routes: milk, etc.
Total clearance: is the sum of clearances from all the elimination pathways. Total clearance is often important to determining the half life of drugs in consideration.

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Test your knowledge on important pharmacology concepts such as pharmacodynamics, pharmacokinetics, and pharmacogenomics. This quiz covers various aspects of drug administration, toxicology, and the economic implications of pharmacological practices. Perfect for students studying pharmacology or related fields.