Pharmacology: Drug Administration Routes

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Questions and Answers

What is the most commonly used route for drug administration?

Sublingual

Rectal

Oral (correct)

Transdermal

What is a disadvantage of the oral route of drug administration?

Poor bioavailability in some cases (correct)

Rapid onset of action

Decreased risk of drug destruction

High patient acceptability

Which of the following routes is least suitable for administration during emergencies?

Oral (correct)

Rectal

Transdermal

Sublingual

When considering drug administration, which factor primarily influences the route selected?

Drug and patient-related factors Signup and view all the answers

What form can drugs take when administered orally?

Solid or liquid forms Signup and view all the answers

What is a notable disadvantage of oral drug administration?

It's not suitable for uncooperative patients. Signup and view all the answers

What is an advantage of sublingual drug administration?

Avoids the gastrointestinal tract. Signup and view all the answers

Which of the following drugs is likely unsuitable for rectal administration?

Intravenous infusions. Signup and view all the answers

What is a major limitation of oral drug administration concerning specific drug types?

Drugs destroyed by digestive juices cannot be used. Signup and view all the answers

For which situation is rectal administration especially advantageous?

In cases where oral administration is unsuitable. Signup and view all the answers

Which of the following statements about oral administration is true?

Food content may affect drug absorption. Signup and view all the answers

Why might a healthcare provider choose sublingual administration?

It avoids first-pass metabolism. Signup and view all the answers

What is one disadvantage of rectal drug administration?

Patients may find it inconvenient. Signup and view all the answers

What is the primary advantage of the parenteral route of drug administration?

Rapid onset of action Signup and view all the answers

Which route of drug administration is least suitable for self-administration?

Intravenous infusion Signup and view all the answers

Which of the following is a disadvantage of the topical route of drug administration?

Chronic use may lead to local adverse effects Signup and view all the answers

What does the process of ADME in pharmacology stand for?

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

What is a key characteristic of the inhalation route of drug administration?

Minimized systemic effect Signup and view all the answers

Why is the rectal route considered to have limitations?

It may cause discomfort to patients Signup and view all the answers

What is one of the main reasons why not all drugs are suitable for transdermal administration?

Poor skin permeability of many drugs Signup and view all the answers

How must a drug be processed in the body to exert its pharmacological effect?

Absorbed, distributed, and then reach the target site Signup and view all the answers

What does a 50% oral bioavailability of Nifedipine indicate?

50% of the oral dose reaches systemic circulation unchanged Signup and view all the answers

Which factor does NOT affect drug distribution in the body?

Molecular weight of the drug Signup and view all the answers

What primarily determines the capability of a drug to cross cell membranes?

The free fraction of the drug in plasma Signup and view all the answers

Why might lipid-soluble drugs be retained in the body for extended periods?

They are stored in adipose tissue and released slowly Signup and view all the answers

What role does plasma protein binding play in drug action?

Free, unbound drugs are responsible for pharmacological effects Signup and view all the answers

What is the primary factor affecting drug absorption in the ileum?

Surface area Signup and view all the answers

Which statement accurately describes bioavailability?

It is defined as the fraction of the administered drug reaching the systemic circulation as an intact drug. Signup and view all the answers

Why does Tenofovir have low bioavailability when administered orally?

Negative charges on its molecules limit absorption. Signup and view all the answers

What role does cobicistat play when used with Darunavir?

It inhibits metabolism to increase the bioavailability of Darunavir. Signup and view all the answers

Which factor is NOT identified as affecting drug bioavailability?

Hydration levels in the body Signup and view all the answers

Which drug is indicated to have 100% bioavailability when administered intravenously?

Any drug administered IV Signup and view all the answers

What does high hepatic first-pass metabolism imply for a drug's bioavailability?

Lower bioavailability resulting from metabolic degradation prior to systemic circulation. Signup and view all the answers

Which physiological factor can enhance drug absorption over the stomach?

Higher surface area of the intestines Signup and view all the answers

What is the primary effect of adding glucuronic acid to a drug?

Inactivates the drug Signup and view all the answers

What is likely to happen to a patient with renal failure regarding drug elimination?

Prolonged drug action Signup and view all the answers

What is the purpose of studying drug pharmacokinetics?

To ensure drug levels remain within therapeutic range Signup and view all the answers

If a drug has a half-life of 2 hours, how much would remain after 10 hours if 20 mg was administered?

0.625 mg Signup and view all the answers

What role does the cytochrome P450 system play in drug metabolism?

It is involved in phase I metabolic reactions Signup and view all the answers

What factor primarily affects drug excretion in patients with kidney dysfunction?

Renal blood flow Signup and view all the answers

How can therapeutic drug concentrations be maintained?

Employing multiple dosing regimens Signup and view all the answers

What is the minimal toxic concentration related to in pharmacokinetics?

The concentration above which adverse effects occur Signup and view all the answers

Study Notes

Handling of Drugs by the Body

Pharmacology is the science dealing with the use of drugs and its many branches, including pharmacokinetics and pharmacodynamics.
Pharmacokinetics is the study of how the body handles drugs.
The aim of the session is to distinguish pharmacokinetics from pharmacodynamics, contrast oral administration advantages and disadvantages, discuss the role of absorption, distribution, metabolism, and excretion in governing drug concentration, and appraise the role of drug half-life and therapeutic window.
This session is an introduction to pharmacokinetics and is not directly tied to any single case study.

Aim of the Session

Students will be able to differentiate pharmacokinetics from pharmacodynamics.
Students will be able to contrast the benefits and drawbacks of oral administration versus other routes, focusing on bioavailability.
Students will be able to explain the roles of absorption, distribution, metabolism, and excretion in determining drug concentration and its effects (therapeutic/toxic).
Students will be able to assess the relevance of drug half-life and therapeutic window in relation to drug dosages.

Pharmacology and Its Branches

Pharmacology encompasses many areas, key among them are pharmacokinetics and pharmacodynamics.
Pharmacokinetics looks at how drugs enter the body, spread inside it, and eventually leave the body.
Pharmacodynamics focuses on the drug's effects on the body—how it changes cellular function and/or behavior.

Routes of Drug Administration

There are several routes of drug administration, each with its pros and cons. Oral is the most common.
Rectal, sublingual, enteral, parenteral, topical, transdermal, and inhalation are other routes.
Oral administration is convenient and common, yet it may not be suitable in emergencies or for patients with severe symptoms.

Oral Route

Oral drug administration occurs via the mouth, in solid or liquid forms.
It is among the safest and easiest routes.
It typically has disadvantages such as poor absorption and drug destruction during processing through the digestive system.

Routes of Drug Administration: Advantages and Disadvantages

Different routes for drug administration provide advantages and disadvantages. These differences influence their use.

ADME Process

ADME stands for Absorption, Distribution, Metabolism, and Excretion. This summarizes the process drugs undergo in the body.

ADME Process: Absorption

Absorption is the process of transferring a drug from its administration site to the bloodstream.
Factors like drug formulation, physical and chemical properties of the drug, and host factors (e.g., pH) affect absorption.

Factors Affecting Drug Absorption

Host factors, such as pH, affect how well drugs absorb.
Drugs that are more lipid-soluble are absorbed more easily.
The size and ionization of the drug molecule also influence absorption.

ADME Process: Distribution

Distribution is the movement of a drug in the body. Factors like drug solubility and blood flow influence how quickly and to which organs a drug diffuses.
Plasma protein binding limits drug distribution to targeted tissues.

ADME Process: Metabolism

Metabolism is the modification of a drug in the body. It transforms the compound into a different chemical form.
It primarily takes place in the liver (not always exclusive to the liver).
It often inactivates or transforms the drug to be excreted.

ADME Process: Excretion

Excretion is the process of removing a drug and/or its metabolites from the body.
The kidneys are the main organs for excretion of water-soluble substances, but other organs also play a role. This process is affected by renal blood flow and urine pH.

Bioavailability

Bioavailability is the fraction of administered drug that reaches the systemic circulation.
IV administration has 100% bioavailability because the drug directly goes to systemic circulation.

Half-life

Half-life is the time required for the drug concentration in the blood to decrease by half.
Knowing the half-life is critical for dosing regimens and drug elimination.

Dosing Regimens

Dosing regimens consider factors like half-life to determine appropriate times between drug administration.
Steady state is reached when the rate of drug administration equals the rate of elimination, and the concentration remains relatively constant.

Therapeutic Window

The therapeutic window is the range of drug concentrations between minimal effective concentration and minimal toxic concentration.
Drugs with narrow therapeutic windows require careful monitoring.

Summary of Key Concepts

Understanding how the body handles drugs is essential in clinical practice.
Multiple factors affect drug action, including administration route, absorption, distribution, metabolism, and excretion.
Half-life and steady state are crucial in determining dosing regimens.
The therapeutic window helps determine appropriate doses.

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Description

Test your knowledge on the various routes of drug administration in pharmacology. This quiz covers advantages and disadvantages of oral, sublingual, rectal, and parenteral methods. Understand how route selection impacts drug efficacy and emergency situations.