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Questions and Answers
What is a major disadvantage of oral drug administration?
What is a major disadvantage of oral drug administration?
What is a disadvantage of sublingual administration?
What is a disadvantage of sublingual administration?
Which of the following is NOT a characteristic of inhalation administration?
Which of the following is NOT a characteristic of inhalation administration?
Which administration route is most suitable for patients who are vomiting?
Which administration route is most suitable for patients who are vomiting?
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What is a primary advantage of parenteral administration?
What is a primary advantage of parenteral administration?
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Which statement about rectal administration is correct?
Which statement about rectal administration is correct?
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What does the term 'low bioavailability' imply in drug administration?
What does the term 'low bioavailability' imply in drug administration?
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Which type of diffusion does not require energy and occurs along a concentration gradient?
Which type of diffusion does not require energy and occurs along a concentration gradient?
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What factor primarily influences the ionization and absorption of weak acids?
What factor primarily influences the ionization and absorption of weak acids?
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Why are weak bases better absorbed in the intestine than in the stomach?
Why are weak bases better absorbed in the intestine than in the stomach?
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What role does pKa play in drug absorption?
What role does pKa play in drug absorption?
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Which type of transport requires energy to move substances against a concentration gradient?
Which type of transport requires energy to move substances against a concentration gradient?
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How does blood flow affect drug absorption?
How does blood flow affect drug absorption?
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What process involves the uptake of membrane-bound particles?
What process involves the uptake of membrane-bound particles?
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What form do drugs typically take when they are ionized?
What form do drugs typically take when they are ionized?
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What is a primary advantage of transdermal administration of drugs?
What is a primary advantage of transdermal administration of drugs?
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Which route of drug administration is associated with less first-pass metabolism?
Which route of drug administration is associated with less first-pass metabolism?
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Which mechanism of drug absorption occurs against a concentration gradient and requires energy?
Which mechanism of drug absorption occurs against a concentration gradient and requires energy?
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What characteristic must a drug have to be ideal for transdermal delivery?
What characteristic must a drug have to be ideal for transdermal delivery?
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What is a significant disadvantage of using topical applications for drug delivery?
What is a significant disadvantage of using topical applications for drug delivery?
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Which statement is true regarding the cell membrane and drug absorption?
Which statement is true regarding the cell membrane and drug absorption?
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What determines the ability of water-soluble drugs to be absorbed through the cell membrane?
What determines the ability of water-soluble drugs to be absorbed through the cell membrane?
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The topical application is ideal for delivering medications that target which of the following?
The topical application is ideal for delivering medications that target which of the following?
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What properties must a drug possess to effectively interact with its receptor?
What properties must a drug possess to effectively interact with its receptor?
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Which of the following accurately describes pharmacokinetics?
Which of the following accurately describes pharmacokinetics?
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What is a key disadvantage of the oral route of drug administration?
What is a key disadvantage of the oral route of drug administration?
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What are the four main processes included in pharmacokinetics?
What are the four main processes included in pharmacokinetics?
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Which form of drug administration is known for being self-administered and easy?
Which form of drug administration is known for being self-administered and easy?
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What is an essential characteristic of a practical drug in relation to its duration of action?
What is an essential characteristic of a practical drug in relation to its duration of action?
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Which type of drug administration involves delivering medication directly into the bloodstream?
Which type of drug administration involves delivering medication directly into the bloodstream?
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What aspect of a drug's delivery system does the term 'bioavailability' refer to?
What aspect of a drug's delivery system does the term 'bioavailability' refer to?
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Study Notes
Introduction to Pharmacology
- Galala University, powered by Arizona State University
- Pharmacology I, taught by Assoc. Prof. Mohamed Hamzawy
Nature of Drugs
- To interact chemically with its receptor, a drug molecule must have appropriate size, electrical charge, shape, and atomic composition.
- A diagram illustrates the drug interacting with the receptor to form a drug-receptor complex, triggering a response or pharmacological effect.
Drug Action and Distance
- Drugs are often administered at a location distant from their intended site of action.
- Examples include oral medication to relieve headaches.
- A useful drug must possess properties enabling transport from the site of administration to its targeted site of action.
- This process is described as Pharmacokinetics, which includes the processes of absorption, distribution, metabolism (and excretion) of a drug.
Drug Action and Practical Considerations
- A practical drug should be inactivated or excreted by the body at a rate appropriate for maintaining a needed duration of action.
Divisions of Pharmacology
- Two main divisions of pharmacology are: pharmacokinetics and pharmacodynamics.
- Pharmacokinetics describes what the body does to the drug (ADME)
- Pharmacodynamics describes what the drug does to the body.
Pharmacokinetics (ADME)
- Absorption: How the drug moves from the administration site to the bloodstream.
- Distribution: How the drug moves to various body tissues and organs.
- Metabolism: How the drug is altered or broken down.
- Excretion: How the drug is removed from the body.
- Diagrams show the relationships between these processes, highlighting drug administration, absorption, distribution to the blood, metabolism, excretion, and the site of action.
Routes of Drug Administration
- Enteral: Oral, sublingual/buccal.
- Parenteral: Intramuscular (IM), intravenous (IV), subcutaneous (SC), Intrathecal
- Other: Oral Inhalation, Nasal inhalation, Topical, Transdermal, Rectal
Oral Route of Administration
- Advantages: Easy self-use, safe, convenient, cheap, no need for sterilization.
- Disadvantages: Slow effect, incomplete absorption (low bioavailability), destruction by gastrointestinal tract (GIT), first pass effect, GIT irritation, food-drug interactions, and drug-drug interactions. The route is not suitable for patients experiencing vomiting, unconscious, or for emergency situations.
First Pass Metabolism
- Oral drugs are first metabolized by the liver (via portal circulation) before entering the systemic circulation which significantly reduces the effective dose of the drug.
- This results in low bioavailability and short duration of action.
- The process involves the liver gut wall and gut lumen.
Sublingual Administration
- Advantages: Rapid effect (emergency), no first-pass metabolism, high bioavailability.
- Disadvantages: Not suitable for irritant drugs.
Parental Administration
- Advantages: High bioavailability, rapid action (emergency), no first-pass metabolism
- Disadvantages: Infection risk, sterilization required, pain, skill needed, anaphylaxis, and expensive.
Inhalation Administration
- Advantages: Rapid absorption, rapid effects, local action, less side effects, no first pass effect
- Disadvantages: Only a few drugs suitable for this route.
Rectal Administration
- Advantages: Suitable for vomiting or unconscious patients, irritant, and bad taste drugs.
- Disadvantages: Irregular absorption, low bioavailability, rectal mucosa irritation, not a well-accepted route.
Transdermal Administration
- Advantages: Bypasses first-pass effect, convenient, painless, ideal for lipophilic drugs.
- Disadvantages: Allergies to patches, drug must be highly lipophilic, delayed delivery, and limited to small doses.
Topical Application
- Produces local effects like topical anesthesia.
- Absorption rate varies based on skin properties and drug solubility.
Absorption
- Absorption is the drug transfer from the administration site to the bloodstream.
- The process involves cell membranes containing water-loving and/or water-fearing regions and interspersed transport proteins.
Mechanisms of Drug Absorption
- Simple diffusion
- Active transport
- Facilitated diffusion
- Pinocytosis (endocytosis).
Characteristics of Simple Diffusion
- It follows a concentration gradient.
- It is non-selective.
- It is not saturable.
- It does not require energy.
- There is no need for a carrier protein.
- It depends on the drug's lipid solubility.
Water vs Liquid Soluble Drug Absorption
- Water-soluble drugs are absorbed through aqueous channels.
- Lipid-soluble drugs are absorbed through the lipid cell membrane.
Active Transport
- It occurs against the concentration gradient.
- It requires specific carrier proteins.
- It requires energy.
Facilitated Diffusion
- It occurs along the concentration gradient.
- It requires carriers.
- It is selective.
- It is saturable.
- It does not require energy.
Phagocytosis or Pinocytosis
- Endocytosis is the uptake of membrane-bound particles (such as high-molecular-weight or lipid-insoluble drugs).
- Exocytosis is the expulsion of membrane-bound particles.
Factors influencing absorption
- Effect of pH on drug absorption
- Blood flow to the absorption site
- Total surface area available for absorption
- Contact time at the absorption surface
- Expression of P-glycoprotein.
- P-glycoprotein reduces drug absorption and involved in transportation of drugs from tissues to blood.
Effect of pH on Drug Absorption
- Drugs exist in ionized and non-ionized forms (in equilibrium).
- Non-ionized forms have better membrane permeability.
- pH affects the ionized/non-ionized ratio.
- Acidic drugs are best absorbed in the stomach, while basic drugs are best absorbed in the intestine.
Blood Flow to Absorption Site
- Intestinal blood flow is higher than stomach flow; therefore, intestinal absorption is favoured.
Total Surface Area
- Intestinal surface area is much larger than that of the stomach, leading to significantly higher absorption efficiency.
Contact Time
- Longer contact time at the absorption surface results in greater absorption.
- Conversely, rapid movement through the GI tract reduces absorption.
Expression of P-glycoprotein
- P-glycoprotein is a transmembrane transporter that reduces drug absorption, pumping drugs out of cells into the blood.
- It can be found in various tissues like the liver, kidneys, placenta, intestines and brain.
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Description
This quiz covers the fundamental principles of pharmacology, focusing on the nature of drugs, their actions, and pharmacokinetics. You will explore how drug molecules interact with receptors and the significance of drug administration methods. Test your understanding of key concepts essential for the study of pharmacology.
