Pharmacology and Pharmacokinetics Overview

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Questions and Answers

What is a primary advantage of enteric-coated preparations?

They protect the drug from stomach acid. (correct)

They are less expensive than other formulations.

They allow for more frequent dosing.

They have a faster absorption rate than immediate-release drugs.

What is the main purpose of extended-release (ER) formulations?

To enhance first-pass metabolism.

To reduce the frequency of doses required. (correct)

To achieve higher peaks of drug concentration.

To provide immediate relief from symptoms.

Why are sublingual and buccal routes beneficial for drug administration?

They are less effective than oral medications.

They require more complex administration techniques.

They avoid first-pass metabolism and ensure rapid absorption. (correct)

They provide the slowest drug absorption.

Which drug is commonly cited as benefiting from parenteral administration due to poor absorption in the GI tract?

Insulin Signup and view all the answers

What is a challenge associated with oral drug absorption that is highlighted in the content?

The complex pathways involved in absorption. Signup and view all the answers

How do extended-release formulations maintain therapeutic drug concentrations?

By controlling the release rate of the drug. Signup and view all the answers

What is a common example of a drug that is irritative to the stomach and may benefit from enteric-coating?

Aspirin Signup and view all the answers

In which scenario is parenteral administration most often utilized?

When quick action is required and oral medication is impractical. Signup and view all the answers

Which form of a weak base is able to permeate through cell membranes more readily?

Uncharged form (B) Signup and view all the answers

How does pH influence drug absorption in weak acids?

A higher pH decreases the proportion of uncharged forms. Signup and view all the answers

Which of the following factors enhances drug absorption through the intestine?

Greater surface area due to microvilli Signup and view all the answers

What role does P-glycoprotein play in drug absorption?

Reduces drug absorption by pumping drugs out of cells. Signup and view all the answers

What happens to drug absorption in cases of severe diarrhea?

Absorption is decreased due to rapid movement through the GI tract. Signup and view all the answers

Which property of weak bases is determined by its pKa?

The effective concentration of the uncharged and charged forms Signup and view all the answers

Which statement correctly describes the absorption from the intestines compared to the stomach?

Drug absorption is favored from the intestine due to higher blood flow. Signup and view all the answers

What is the main consequence of increased expression of P-glycoprotein at the absorption site?

Decreased drug absorption leading to lower effective doses. Signup and view all the answers

What is the significance of first-pass metabolism in orally administered drugs?

It reduces the bioavailability of the drug. Signup and view all the answers

Which factor does NOT influence the distribution of a drug from plasma to interstitium?

Drug stability in the stomach Signup and view all the answers

How does the lipophilicity of a drug affect its distribution?

It enhances the drug's ability to enter the CNS. Signup and view all the answers

What could lead to a decreased rate of absorption of a drug?

Improper salt form Signup and view all the answers

Which of the following drugs is indicated to have chemical instability in the gastric environment?

Insulin Signup and view all the answers

What factor contributes to the rapid distribution of propofol into the CNS?

High blood flow to the brain Signup and view all the answers

What is the primary determinant of capillary permeability for drug distribution?

Capillary structure and drug nature Signup and view all the answers

Which tissue type is likely to have the lowest rate of blood flow?

Skeletal muscle Signup and view all the answers

What is the primary factor that differentiates bioavailability between oral and intravenous drug administration?

First-pass hepatic metabolism Signup and view all the answers

What is meant by the term bioavailability in pharmacology?

The rate and extent to which a drug reaches systemic circulation Signup and view all the answers

Which statement correctly explains why some orally administered drugs have low bioavailability?

They are poorly absorbed across the gastrointestinal tract. Signup and view all the answers

How is bioavailability typically determined for a drug?

By comparing IV and oral administration plasma levels Signup and view all the answers

What role does first-pass hepatic metabolism play in the bioavailability of orally administered drugs?

It can significantly decrease the amount of active drug reaching systemic circulation. Signup and view all the answers

What characteristic is essential for a drug to be efficiently absorbed in the body?

The drug should be lipophilic but also have some aqueous solubility. Signup and view all the answers

Which of the following would likely lead to a decrease in the bioavailability of a drug?

Rapid first-pass metabolism by the liver Signup and view all the answers

What is the significance of the area under the curve (AUC) in determining bioavailability?

It reflects the concentration of the drug over time in the bloodstream. Signup and view all the answers

Which route of drug excretion is primarily responsible for eliminating anesthetic gases?

Lungs Signup and view all the answers

What is the equation used to calculate total body clearance?

CLtotal = CLhepatic + CLrenal + CLpulmonary + CLother Signup and view all the answers

Which condition can lead to an increase in drug half-life?

Renal disease Signup and view all the answers

What is a potential risk of drug excretion into breast milk?

Potential exposure of the infant to medications Signup and view all the answers

Which component is not included in the total body clearance equation?

CLgastrointestinal Signup and view all the answers

What might necessitate a decrease in drug dosage?

Hepatic insufficiency Signup and view all the answers

What happens when a drug undergoes decreased metabolism due to a concomitant drug?

Drug half-life increases Signup and view all the answers

What is a minor route of drug excretion compared to others?

Sweat Signup and view all the answers

What does first-order kinetics of drug elimination indicate?

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

What is the formula for calculating the volume of distribution (Vd)?

Vd = Dose / C0 Signup and view all the answers

Which method is typically used to analyze drug concentration elimination over time?

Plotting the log of plasma drug concentration versus time. Signup and view all the answers

Which of the following does NOT serve as a major route of drug elimination?

Dermal excretion Signup and view all the answers

What are phase I and phase II reactions primarily responsible for?

Making lipophilic drugs more polar for elimination. Signup and view all the answers

Why are lipophilic drugs less efficiently eliminated by the kidneys?

They are reabsorbed in the distal convoluted tubules. Signup and view all the answers

What does clearance (CL) measure in drug elimination?

The volume of plasma from which the drug is completely removed per unit of time. Signup and view all the answers

In which scenario would a drug exhibit zero-order kinetics?

When the drug is administered in high doses, such as aspirin. Signup and view all the answers

Study Notes

Pharmacology

Pharmacology is the study of substances interacting with living systems, particularly by binding to regulatory molecules, activating or inhibiting normal body processes.
Drug-body interactions are categorized into pharmacodynamic (drug on body) and pharmacokinetic (body on drug) processes.
Pharmacodynamic processes determine drug classification and appropriateness for specific symptoms/diseases.
Pharmacokinetic processes involve drug absorption, distribution, metabolism, and elimination.

Pharmacokinetics

Absorption: Drug entry into plasma (directly or indirectly) from the site of administration.
Distribution: Drug movement from bloodstream to interstitial and intracellular fluids. Reversible process.
Metabolism: Drug biotransformation primarily by the liver (or other tissues).
Elimination: Drug and metabolite removal from the body (urine, bile, feces).

Routes of Drug Administration

Enteral: Safest and most common, convenient, and economical method (e.g., oral, sublingual, buccal).
- Oral: Fast self-administration; complex absorption pathways; complications include low gastric pH.
- Enteric-coated: Protects drug from stomach acid, releases in the intestines.
- Extended-release: Controls drug release, slower absorption, prolonged action, improves patient compliance.
Parenteral: Direct drug introduction into the body via injection.
- Intravenous (IV): Rapid effect and maximum control; administered as a bolus or infusion.
- Intramuscular (IM): Rapid or sustained release; appropriate for vaccines, medications requiring slow absorption.
- Subcutaneous (SC): Slower absorption than IV; suitable for drugs needing sustained effects. Suitable for insulin or heparin.
- Intradermal: Localized effect; used for diagnostic testing, desensitization.
Other: Oral inhalation, nasal preparations, topical, intrathecal/intraventricular.
- Oral Inhalation/Nasal Preparations : Rapid delivery to mucous membranes, quick effects. Good for respiratory issues (e.g., asthma).
- Intrathecal/Intraventricular: Used for local, rapid CNS effects. Bypasses blood-brain barrier.
- Topical: Applied directly to the skin or other surface for local effect.
- Transdermal (patch): Slower, sustained release across the skin; for systemic effect.

Absorption Mechanisms

Passive Diffusion: Drugs move from high to low concentration across a membrane. Important for most drugs.
Facilitated Diffusion: Carrier proteins facilitate drug transport, not requiring energy. Dependent on concentration gradient.
Active Transport: Carrier proteins move drugs against concentration gradients, requiring energy.

Bioavailability

Bioavailability: The fraction of administered drug reaching systemic circulation unchanged.
Factors affecting bioavailability: First-pass metabolism, drug solubility, total surface area at absorption site, contact time at absorption site, drug formulation, and expression of P-glycoprotein.

Drug Distribution

Blood flow to the absorption site, total surface area for absorption, contact time at the absorption surface.
Capillary permeability: determined by capillary structure and chemical properties of the drug.
Drug binding to plasma and tissue proteins (e.g., albumin).
Lipophilicity: determines drug's ability to cross cell membranes.

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Description

This quiz explores the fundamentals of pharmacology and pharmacokinetics. It covers drug-body interactions, including pharmacodynamic and pharmacokinetic processes, as well as routes of drug administration. Understand how drugs affect the body and how the body processes drugs.