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What is a pharmaceutical drug?
What is a pharmaceutical drug?
Any substance used in the diagnosis, treatment, or prevention of a disease.
All drugs must be applied directly at their site of action.
All drugs must be applied directly at their site of action.
False
What is the site of action of a drug?
What is the site of action of a drug?
The location in the body where the drug performs its desired function.
What is the common analogy used to describe drug-target interactions?
What is the common analogy used to describe drug-target interactions?
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What does the acronym ADME stand for?
What does the acronym ADME stand for?
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Oral administration is the least preferred route by patients.
Oral administration is the least preferred route by patients.
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Most drugs are small enough to cross the capillary endothelium readily by __________.
Most drugs are small enough to cross the capillary endothelium readily by __________.
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What is the rectal route of drug administration?
What is the rectal route of drug administration?
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Match the following drug administration routes with their descriptions:
Match the following drug administration routes with their descriptions:
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What are the two ways a drug can enter the vascular space?
What are the two ways a drug can enter the vascular space?
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What is distribution in pharmacology?
What is distribution in pharmacology?
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What does apparent volume of distribution (Vd) represent?
What does apparent volume of distribution (Vd) represent?
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How does the body eliminate a drug from plasma?
How does the body eliminate a drug from plasma?
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What is clearance (Cl) in pharmacology?
What is clearance (Cl) in pharmacology?
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Which of the following processes allows for drug elimination unchanged from the body?
Which of the following processes allows for drug elimination unchanged from the body?
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What role does the liver play in drug elimination?
What role does the liver play in drug elimination?
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How are drugs eliminated in sweat?
How are drugs eliminated in sweat?
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What is first pass metabolism?
What is first pass metabolism?
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What does Cmax represent?
What does Cmax represent?
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What is the significance of Tmax?
What is the significance of Tmax?
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What is the role of the kidneys in drug elimination?
What is the role of the kidneys in drug elimination?
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Study Notes
Pharmaceutical Sciences Overview
- Encompasses interdisciplinary studies related to medicines including design, action, delivery, disposition, and use.
- Integrates principles from chemistry, biology, mathematics, physics, and chemical engineering.
Key Subfields
- Pharmacology: Study of drug action.
- Pharmacodynamics: Examines the effects of drugs on biological systems.
- Pharmacokinetics: Focuses on how drugs move through the body.
- Pharmaceutical Toxicology: Investigates drug toxicity and adverse effects.
- Medicinal Chemistry: Involves the design and development of pharmaceutical agents.
- Pharmaceutics: Concerned with drug formulation and delivery.
- Pharmacogenomics: Studies genetic influence on drug response.
Definitions and Drug Action
- Pharmaceutical Drug: Any substance for disease diagnosis, treatment, or prevention; can be synthetic, semi-synthetic, or natural.
- Most drugs alter physiological or biochemical processes by interacting with specific body parts (organs, tissues, cells).
Drug Target Interaction
- Site of Action: Where the drug performs its intended effect.
- Drug targets are usually biomolecules such as proteins or nucleic acids involved in disease processes.
- Drug action often requires binding to the target, akin to a lock and key mechanism.
Drug Administration and Delivery
- Drugs often need to be administered at a distance from the site of action due to practicality.
- Dosage Forms: Incorporated into systems like tablets or patches for controlled release.
- Administration methods are influenced by drug properties, physiological factors, and patient preferences.
Absorption and Distribution
- Absorption: Drug enters the bloodstream from the administration site.
- Drug absorption involves crossing epithelial membranes, critical for reaching systemic circulation.
- Distribution: Describes how the drug spreads throughout body tissues after absorption.
- ADME: Acronym representing Absorption, Distribution, Metabolism, Excretion which outlines drug behavior in the body.
Mechanisms of Membrane Transport
- Epithelial Tissue: Acts as a barrier that drugs must cross, often primarily by transcellular mechanisms.
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Transport Mechanisms:
- Passive Diffusion: Small molecule transport without energy.
- Carrier-mediated Transport: Utilizes proteins to transport larger molecules.
- Endocytosis/Exocytosis: Mechanisms for transporting macromolecules.
Systemic vs. Localized Administration
- Topical Administration: Applied directly to the target area for localized effect (e.g., creams).
- Systemic Administration: Drug absorbed into the bloodstream to reach distant sites; necessary when the target is hard to access.
Routes of Administration
- Oral: Preferred route; drug absorbed through the GI tract into the bloodstream.
- Parenteral: Involves injections and bypasses gastrointestinal barriers; includes intravenous (IV) and intramuscular (IM).
- Alternative routes include rectal, transdermal, pulmonary, and nasal, depending on clinical needs and drug characteristics.
Drug Distribution Dynamics
- Factors affecting drug distribution include blood flow to tissues, tissue permeability, and binding to proteins in blood.
- Volume of Distribution (Vd): A measure indicating the extent of drug distribution throughout body tissues relative to blood concentration.
Epithelial Barriers
- Epithelial tissues line internal cavities and surfaces of the body, acting as barriers for drug absorption.
- Endothelial Tissue: Specialized epithelial lining blood vessels, facilitating drug transport via paracellular pathways where junctions are looser.
These notes outline essential concepts in the pharmaceutical sciences, highlighting interactions, absorption processes, and the importance of drug delivery systems in achieving therapeutic outcomes.### Drug Elimination and Clearance
- Drugs are eliminated from the plasma primarily through excretion (urine, bile) or metabolism (conversion to metabolites).
- Physicochemical properties influence drug elimination: lipophilicity, ionization, protein binding, and molecular weight.
- Polar compounds favor excretion, while lipophilic compounds are typically metabolized.
- Clearance (Cl) is calculated as: Cl (mL/min) = drug elimination rate (mg/min) / drug plasma concentration (mg/mL).
Excretion Processes
- Excretion occurs without chemical change; drugs leave the body unchanged or as parent compounds.
- Major excretion routes include urine, bile, saliva, sweat, breast milk, and exhaled air, with urine being the primary pathway.
- Kidneys play a crucial role in regulating blood composition and excreting drugs and metabolites.
Liver's Role in Drug Elimination
- Liver metabolizes drugs and secretes bile, which may facilitate biliary excretion.
- Biliary excretion involves the removal of drugs via bile into the duodenum for fecal elimination.
- Metabolism typically produces more polar and less biologically active metabolites than the parent drug.
Excretion in Various Fluids
- Saliva: Limited excretion route; however, it can be used for monitoring drug levels.
- Breast Milk: Many drugs can pass into breast milk, posing risks to infants.
- Sweat: Minimal excretion; primarily relevant for environmental conditions and testing for illegal drugs.
- Expired Air: Volatile drugs and anesthetics are excreted, detectable via breathalyzers.
Metabolism (Biotransformation)
- Involves enzyme-catalyzed reactions that convert drugs into metabolites.
- Drug properties dictate metabolism; polar drugs can be readily excreted, while lipophilic drugs generally require conversion to polar forms.
- Biliary excretion depends on molecular weight; compounds >500 Da are mainly excreted via bile.
Pharmacokinetics Terms
- Cmax: Peak concentration of the drug in plasma.
- Tmax: Time to reach Cmax.
- AUC: Total drug exposure over time.
- t1/2 (half-life): Time for drug concentration to decline to half its peak level.
- Cmin: Minimum concentration (trough level) of the drug in plasma.
Enzymatic Drug Metabolism
- Enzymes metabolizing drugs exist in many tissues, but significant metabolism occurs mainly in high-enzyme concentration organs like the liver.
- First-pass metabolism can activate prodrugs into pharmacologically effective forms after liver metabolism.
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