Pharmacology 1 - Drug Absorption

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a significant advantage of using non-gastrointestinal routes for drug administration?

They avoid the effects of gastrointestinal factors and first pass metabolism. (correct)

They ensure that all drugs are absorbed equally well.

They allow for slower absorption into the bloodstream.

They are generally less invasive than oral administration.

Which of the following best describes the first pass metabolism effect?

Has no impact on drugs administered via non-oral routes.

Is necessary to activate certain prodrugs for their therapeutic effects.

Refers to the metabolism of a drug before it enters the systemic circulation. (correct)

Enhances the bioavailability of drugs taken orally.

When might sublingual drug administration be preferred over oral administration?

When there is a need for drug delivery in large volumes.

When a rapid onset of action is required and swallowing is difficult. (correct)

When the drug is known to cause severe gastrointestinal irritation.

When drug absorption through the gastrointestinal tract is significantly enhanced.

What is a potential risk of increased intestinal permeability, often referred to as 'leaky gut syndrome'?

Decreased absorption of essential nutrients. Signup and view all the answers

Which of the following statements about intravenous drug administration is correct?

It allows for immediate effects and rapid titration of dosage. Signup and view all the answers

What is primarily responsible for the rapid absorption of inhaled medications?

Large surface area and rich blood supply of the lungs Signup and view all the answers

Which of the following routes bypasses first pass metabolism?

Sublingual administration Signup and view all the answers

How does first pass metabolism affect drug bioavailability?

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

What is a characteristic of intravenous drug administration?

It ensures 100% bioavailability directly into the bloodstream. Signup and view all the answers

What is a potential disadvantage of using inhalational routes for drug delivery?

Patients must be conscious to use inhalation devices. Signup and view all the answers

What is a key factor that affects the absorption rate of drugs administered via the intramuscular route?

Blood flow to the site Signup and view all the answers

Which of the following statements about subcutaneous administration is true?

Absorption is faster than through the intradermal route. Signup and view all the answers

Why might a drug administered sublingually lead to a faster systemic effect compared to oral administration?

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

Which of the following drugs is most commonly used in a dental emergency and can be administered by the intramuscular route?

Epinephrine Signup and view all the answers

What is the importance of varying injection sites for subcutaneous drug administration?

To prevent tissue damage and lipodystrophy. Signup and view all the answers

Which of the following drugs can be effectively administered via the buccal route for rapid absorption during a dental emergency?

Nitroglycerin tablets Signup and view all the answers

How does the skin’s barrier affect the absorption of topically applied drugs compared to those applied to the oral mucosa?

Skin is less permeable than oral mucosa. Signup and view all the answers

Which factor does NOT contribute to the decreased absorption rate of an intramuscularly administered drug?

High blood flow Signup and view all the answers

Which type of molecule can diffuse freely across cellular membranes due to lipid solubility?

Non-polar molecules Signup and view all the answers

How does the pH of the environment affect the absorption of weakly acidic medications?

More ionised in acidic environments Signup and view all the answers

What happens to penicillin G when exposed to the acidic conditions of the stomach?

It undergoes hydrolysis and loses antibiotic activity Signup and view all the answers

Why are weakly basic medications better absorbed in an alkaline environment?

They become more lipid soluble Signup and view all the answers

What mechanism is primarily responsible for the movement of polar molecules across cellular membranes?

Solute carriers Signup and view all the answers

What is a primary reason for using intravenous drug administration in clinical settings?

To ensure rapid drug absorption into the bloodstream Signup and view all the answers

Which scenario is least likely to necessitate the use of parenteral drug administration?

When a patient prefers taking a tablet for convenience Signup and view all the answers

Which of the following routes is primarily associated with avoiding the risks of tissue damage related to drug delivery?

Intravenous route Signup and view all the answers

What characteristic of intravenous administration allows for continuous drug delivery?

Use of infusion pumps Signup and view all the answers

What is a potential implication of increased intestinal permeability due to gastrointestinal diseases?

Potential bacterial entry into the bloodstream Signup and view all the answers

What is one characteristic of inhalational anesthetics like sevoflurane and isoflurane?

They can be delivered via a face mask using a vaporizer. Signup and view all the answers

Which delivery device uses the patient's inspiration to deliver medication?

Dry powder inhaler Signup and view all the answers

What is a significant reason inhaled medications have rapid absorption compared to other routes?

The lungs have a large surface area and rich blood supply. Signup and view all the answers

Which factor is NOT true regarding the use of inhalational medications?

They act only locally and do not have systematic effects. Signup and view all the answers

What practice is common for enhancing the effectiveness of a metered dose inhaler?

Using it with a spacer device. Signup and view all the answers

What is the primary purpose of enteric coatings on tablets?

To prevent dissolution in the stomach and promote release in the intestines Signup and view all the answers

Which of the following drugs used in dentistry is affected by first pass metabolism, making it unsuitable for oral administration?

Lidocaine Signup and view all the answers

How does sublingual administration improve drug absorption compared to oral administration?

It avoids first pass metabolism and allows direct entry into circulation Signup and view all the answers

Which statement is true about the hepatic portal system's role in drug metabolism?

It metabolizes many drugs before they enter the general circulation Signup and view all the answers

Which type of material is commonly used for modern enteric coatings?

Synthetic polymeric materials and polyacids Signup and view all the answers

What physiological factor can impede drug absorption via oral administration?

Presence of acidic foods in the stomach Signup and view all the answers

Which of the following conditions may lead to delayed gastric emptying?

Opioid use and certain GI diseases Signup and view all the answers

What is a significant disadvantage of administering an acid-labile drug orally?

It could lead to incomplete absorption due to degradation in the stomach Signup and view all the answers

What factor could lead to a decrease in the absorption rate of a drug administered by the intramuscular route?

Addition of adrenaline Signup and view all the answers

Which of the following sites is NOT typically used for intramuscular injections?

Inguinal region Signup and view all the answers

Why is the absorption rate of drugs greater via the sublingual/buccal route compared to the oral route?

Direct access to systemic circulation Signup and view all the answers

Which of the following drugs would likely be administered subcutaneously for diabetes management?

Insulin Signup and view all the answers

What complication can arise from not varying injection sites during subcutaneous drug administration?

Subcutaneous abscess formation Signup and view all the answers

What type of formulation is NOT suitable for sublingual or buccal administration?

Ointments Signup and view all the answers

What is a significant barrier to the absorption of drugs through the skin compared to the oral mucosa?

Tight layers of skin Signup and view all the answers

Which of the following measures can enhance the absorption rate of intramuscularly administered drugs?

Increasing local blood flow Signup and view all the answers

What does pharmacokinetics primarily focus on in relation to drug administration?

The body’s interaction and processing of drugs over time Signup and view all the answers

Which route of drug administration is least likely to be affected by first pass metabolism?

Sublingual route Signup and view all the answers

Which factor is least likely to influence the bioavailability of an orally administered drug?

The age of the patient Signup and view all the answers

What is the primary disadvantage associated with the oral route of drug administration?

Bioavailability can be significantly altered by first pass metabolism Signup and view all the answers

Which of the following best describes the term 'bioavailability'?

The extent and rate at which the active ingredient or active moiety is absorbed from a drug product Signup and view all the answers

What is a common characteristic of drugs administered via the parenteral route?

They usually have higher bioavailability than oral administration Signup and view all the answers

In terms of drug formulation, which characteristic can impact the absorption of orally administered drugs?

The drug's coating and formulation Signup and view all the answers

Regarding the enteral administration of drugs, which of the following statements is most accurate?

Sublingual administration is effective due to minimal first pass metabolism Signup and view all the answers

Which physiological factor can affect the absorption of drugs administered via the intramuscular route?

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

Study Notes

Pharmacology 1 - Absorption

The presentation covers how drugs enter the body.
Learning objectives: define pharmacokinetics and pharmacodynamics, understand different drug administration routes (parenteral and enteral), discuss issues with skin and oral mucosa, and understand first pass metabolism.
The spiral learning module in pharmacology 1 covers how drugs enter the body, which is later compared to understanding how drugs act (pharmacology 2).
Pharmacokinetics is the body's actions on the drug, over time.
This lecture focuses on routes of administration.
The session will focus on absorption.
The following session will cover distribution.
Absorption is how drugs enter the body.

Enteral Route

Drugs are administered via the oral, sublingual, and rectal routes.
This is the most common route due to convenience ("per os" - by mouth).
Bioavailability varies when administered orally (the proportion of drug reaching systemic circulation).
Some drugs are destroyed by enzymes or acid in the gut.
First-pass metabolism can cause drugs to become inactive.

Bioavailability

Bioavailability describes the proportion of drug reaching systemic circulation after oral administration.
Factors affecting bioavailability include dissolution, gut absorption, and first-pass metabolism.
Drug breakdown in the gut and liver affects bioavailability and the proportion of drug reaching systemic circulation.

Lipid Solubility

Molecules cross cell membranes by diffusion (if lipid soluble), carrier proteins, or pores.
Non-polar/non-ionized molecules move freely (lipophilic/hydrophobic).
Polar/ionized molecules do not move across membranes (lipophobic/hydrophilic).
Most drugs are weak acids or bases; they exist in both ionized and non-ionized forms, and the ratio depends on pH and pKa.
Ionized forms are less lipid soluble.
Acidic drugs are absorbed more in acidic environments.
Basic drugs are absorbed more in basic environments.
The pKa of a drug determines the proportion of drug present in its ionized and nonionized forms at a given pH.

Stability in the Stomach

Penicillins, with a pKa of approximately 3, are unstable under acidic conditions.
Penicillin G, an intravenous penicillin, and Penicillin V, an oral one, react with water and break down in the stomach.
This breakdown creates penicilloic acid, which does not have any therapeutic value.

Homework

Why can't insulin be taken orally? (Hint: consider protein interactions in the gut).
Give examples of drugs used in dentistry that have enteric coatings.
Name two drugs used in dentistry that cannot be given orally due to first-pass metabolism.
What advantages does sublingual administration have over oral administration?
What drug for diabetes can be given subcutaneously? Why is it important to vary injection sites? What complications can occur if this isn't done?
What drug (including concentration) is used topically in the mouth?
How long does it take for absorption across skin vs oral mucosa, and why is oral quicker?
What two common drugs were delivered as aerosols to treat asthma?
What two common inhalationally-administered drugs are no longer used in dental practice?

Parenteral Route

Drugs are administered via a non-gastrointestinal route.
Includes: intravenous, intramuscular, subcutaneous, topical, inhalational, nasal, ocular, otic, and intrathecal.
- Intravenous (IV) : rapid effect, bolus dose, suitable for large volumes.
- Intramuscular (IM): faster absorption than oral, common sites are deltoid, vastus lateralis, ventrogluteal, appropriate delivery for drugs that might damage other tissues if given by other routes.
- Subcutaneous (SC): slower, more sustained absorption than IM, commonly used for injections like insulin administrations.
- Sublingual (SL): drugs dissolve under the tongue, quick delivery for urgent relief.
- Buccal: drugs placed against cheek, similar to sublingually administered drugs.
- Topical: administered directly on the skin or mucous membrane.
- Inhalational: inhaled medications.

First-pass Metabolism

Many drugs are metabolized by the liver before reaching general circulation.
Drugs are metabolized in the liver through phase I and phase II reactions.

Oral Mucosal Permeability

Disease can affect drug absorption from the oral cavity.
Inflammation and damage to the oral mucosa may reduce absorption rate.
Various diseases and conditions of the gastrintestinal tract, like IBS and Crohns can delay emptying of the stomach and reduce drug administration rates.

Increasing Bioavailability

Routes of administration are needed when patients are unable to take medications orally, need frequent administration, when dosages are precise, or absorption from the gut is poor.
Parenteral administration avoids factors affecting oral administration.

Mobility of the Gut

Increased rate of gastric emptying and motility increases the rate of absorption of drugs.
Small intestine's greater surface area promotes absorption.
Diseases can alter gastric emptying.
Food, especially fatty foods, may delay gastric emptying, reducing drug absorption.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the fundamental concepts of pharmacokinetics and pharmacodynamics, focusing on how drugs are absorbed into the body. Learn about the various routes of drug administration, including oral and sublingual methods, and understand the implications of first pass metabolism on drug effectiveness. Prepare to explore the essentials of drug absorption and its significance in pharmacology.