Parenteral Administration Quiz

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Questions and Answers

What is a key advantage of intravenous drug administration?

Allows drug removal after injection

Requires no sterile equipment

Provides the least risk of toxic reactions

Enables 100% bioavailability (correct)

What factor affects drug absorption the most in the oral route?

Gastric pH levels

Rectal mucosa condition

Drug solubility

Patient cooperation (correct)

Inhalation administration provides rapid access to systemic circulation primarily due to:

Direct blood flow from the rectum

Large surface area of the lung (correct)

Presence of fine droplets in the drug solution

Large surface area of the gastrointestinal tract

Which route of drug administration is notably affected by liver metabolism and the first-pass effect?

Oral Signup and view all the answers

What is a disadvantage of using rectal administration for drug delivery?

Erratic and incomplete absorption Signup and view all the answers

What aspect of pharmacogenomics is critical to understanding drug metabolism?

It evaluates genetic variations that influence individual's responses to medications. Signup and view all the answers

Which of the following is a characteristic of intravenous administration?

Drug must be in aqueous solution Signup and view all the answers

Which of the following is not a benefit of sublingual administration?

Does not require specific formulation Signup and view all the answers

What is the primary role of metabolism in pharmacokinetics?

To convert drugs into active or inactive products Signup and view all the answers

Which factor does NOT influence drug passage through cell membranes?

Rate of drug administration Signup and view all the answers

How does polarity affect a drug's kinetic properties?

It affects the drug’s absorption and permeability across membranes Signup and view all the answers

What mechanism primarily drives the distribution of a drug throughout body tissues?

Passive diffusion through capillary membranes Signup and view all the answers

Which statement is true regarding the absorption of drugs from the GI tract?

Only nonionized drugs can be effectively absorbed Signup and view all the answers

In the context of drug action, which property most directly affects membrane permeability?

Ionization characteristics of the drug Signup and view all the answers

Which route of administration is likely to result in the most rapid onset of drug action?

Sublingual administration Signup and view all the answers

How does the pH of the surrounding environment impact weak acid drugs?

It decreases the proportion of ionized drug at low pH Signup and view all the answers

Which mechanism allows drugs to be absorbed against their concentration gradient?

Active Transport Signup and view all the answers

What characterizes facilitated diffusion in drug absorption?

Involves saturable carrier proteins Signup and view all the answers

What primarily determines the rate of drug absorption following oral administration?

Concentration gradient of the drug Signup and view all the answers

Which route of administration is least influenced by the first-pass metabolism?

Intravenous Signup and view all the answers

In which of the following mechanisms are large drug molecules absorbed?

Endocytosis Signup and view all the answers

What is a primary characteristic of aqueous (passive) diffusion?

Shows low structural specificity Signup and view all the answers

What factor primarily influences drug absorption through the parenteral route?

Vascularity of the injection site Signup and view all the answers

Which attribute does NOT apply to facilitated diffusion?

Occurs against a concentration gradient Signup and view all the answers

Study Notes

Parenteral Administration - Intravenous

Bioavailability achieved is 100%, bypassing first-pass metabolism.
Allows precise control of drug levels in the bloodstream.
Provides extremely rapid onset of effects.
Suitable for large volume administration, especially irritant drugs.
Immediate visible toxic reactions can occur, making it the most dangerous route.
Must ensure drug solubility in aqueous solution.
Dosing errors can lead to serious complications.
Once administered, drugs cannot be extracted from the system.

Inhalation

Rapid onset of drug action due to extensive lung surface area.
Commonly used for volatile anesthetics.
Enables management of local conditions such as bronchoconstriction or COPD.
Solutions can be converted to fine droplets via aerosols and nebulizers.

Sublingual Administration

Allows for rapid absorption through the oral mucosa.
Venous drainage from the mouth goes directly to the superior vena cava.
A common example is nitroglycerin.

Rectal Administration

Absorption can be erratic, influenced by rectal vasculature.
Useful when oral administration is impractical, as ~50% of the drug bypasses the liver's first-pass metabolism.
May irritate rectal mucosa, making it suitable for pediatric use.

Oral Administration

Most convenient route, allowing self-administration by patients.
Generally considered safe, with predictable absorption variable.
Can cause gastric irritation (e.g., Aspirin) and is ineffective during vomiting.
Risk of drug degradation by gastric acidity can affect efficacy.

Pharmacogenomics

Focuses on genetic variations affecting drug metabolism and individual responses to medications.

Mechanisms of Drug Absorption/Permeation

Aqueous (Passive) Diffusion: Driven by concentration gradient, occurs spontaneously and bidirectionally.
Facilitated Diffusion: Requires carrier proteins, can be saturated and still driven by concentration gradients.
Active Transport: Involves energy expenditure (ATP) to move drugs against concentration gradients via specific carrier proteins.
Endocytosis/Exocytosis: Engulfing of substances by cell membranes to transport larger molecules.

Therapeutic Window

Refers to the range of drug dosage which can treat disease effectively without having toxic effects.

Routes of Administration of Drugs

Drugs typically enter the body far from their target tissue and require blood transport to reach sites of action.
Absorption rate and efficiency are influenced by the chosen route based on drug properties, patient condition, and the desired therapeutic response.

Parenteral Injections

Intravenous (I.V.): Provides immediate drug action and precise dosage control.
Subcutaneous (S.C.): Useful for poorly absorbed drugs, slower onset.
Intramuscular (I.M.): Allows for rapid absorption and dosing flexibility.
The absorption rate is determined by the solubility of the drug in interstitial fluid.

Pharmacodynamics

Examines how drugs interact with the body, focusing on receptor binding and the resulting effects, including therapeutic and toxic responses.
Agonist drugs activate receptors, while antagonists block action by competing for receptor sites.

Basic Pharmacokinetic Principles

Absorption: Movement from the administration site to systemic circulation.
Distribution: Drug movement from blood to target tissues.
Metabolism: Conversion of drugs into active or inactive forms, often in hepatic tissues.
Excretion: Removal of drugs from the body, primarily through kidneys.

ADME: Drug Passage Principles

Factors influencing drug passage through membranes include molecular size, ionization degree, lipid solubility, and binding to serum or tissue components.

Physicochemical Properties of Drugs

Polarity and lipid solubility inform drug movement and absorption.
Gas exchange across membranes is influenced by partition coefficients, which compare solubility in aqueous vs. oil-like environments.
Large molecular weight often hinders membrane crossing.
Ionization impacts water solubility; uncharged drugs cross membranes more easily than charged forms.

Influence of pH

The pH of the environment can affect the ionization state of weak acids and bases, influencing drug distribution between compartments (e.g., plasma vs. gastric juice).

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Description

This quiz explores the size of molecules and the advantages and disadvantages of parenteral administration, specifically intravenous techniques. It covers key aspects such as bioavailability, dosage control, and potential risks associated with this route of administration.