Controlled Drug Delivery Methods Quiz
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Questions and Answers

What is a major disadvantage of current drug delivery methods?

  • Drugs can be too expensive to produce.
  • Drugs are not always delivered to the desired site of action. (correct)
  • Drugs are always metabolized too quickly.
  • Drugs can have unexpected side effects.

    • What is a key advantage of controlled drug release?

  • It reduces the risk of allergic reactions.
  • It makes drug production more cost-effective.
  • It allows for more frequent drug administration.
  • It ensures a consistent drug concentration at the target site. (correct)

    • What is a major challenge in delivering peptides and proteins as therapeutic agents?

  • Their production is expensive and time-consuming.
  • They are highly reactive and can cause allergic reactions.
  • They are easily degraded in the body, leading to poor bioavailability. (correct)
  • These molecules are often too large to be absorbed by the body.

    • Which of the following is a potential application for controlled release technology?

    <p>All of the above. (D)</p> Signup and view all the answers

    What is the primary function of polymers in drug delivery?

    <p>To prevent the breakdown of drugs in the body. (D)</p> Signup and view all the answers

    What is a major factor that determines the function of a polymer in drug delivery?

    <p>All of the above. (D)</p> Signup and view all the answers

    Which of the following is an example of a natural polymer used in drug delivery?

    <p>Alginates (B)</p> Signup and view all the answers

    Which of the following is an example of a synthetic polymer used in drug delivery?

    <p>Both B and C (B)</p> Signup and view all the answers

    Which of the following is NOT required for intracytoplasmic delivery of a therapeutic agent?

    <p>Ability to target specific organs (D)</p> Signup and view all the answers

    What is the primary function of the Enhanced Permeability and Retention (EPR) effect in drug delivery?

    <p>Enhancing the uptake of drugs by target cells (B)</p> Signup and view all the answers

    What is the main advantage of using thermosensitive hydrogels in drug delivery?

    <p>They can release drugs in response to temperature changes (A)</p> Signup and view all the answers

    What is the purpose of 'protection against biodegradation/metabolism prior to site delivery' in intracytoplasmic delivery?

    <p>To prevent the drug from being broken down by the body's natural defenses before reaching the target cells (D)</p> Signup and view all the answers

    Which of the following is NOT a requirement for a polymer-drug conjugate to be effectively used for intracytoplasmic delivery?

    <p>Ability to exit the cytosol (D)</p> Signup and view all the answers

    Fick's First Law of diffusion describes the relationship between which two factors?

    <p>The flux of a component and the concentration differential across a membrane (C)</p> Signup and view all the answers

    What is the main purpose of lysosomal enzymes in the context of drug delivery using polymer-drug conjugates?

    <p>To degrade and break down the polymer-drug conjugate (D)</p> Signup and view all the answers

    Which of the following is a key challenge faced in using polymers for drug delivery?

    <p>All of the above (D)</p> Signup and view all the answers

    Which of the following polymers is a common biodegradable polymer used in drug delivery?

    <p>Poly(lactide-co-glycolide) (PLGA) (C)</p> Signup and view all the answers

    What factor determines the swelling and gel flexibility in three-dimensional hydrogels?

    <p>Cross-linking between polymer chains (D)</p> Signup and view all the answers

    Which mode of drug release is characteristic of hydrogels?

    <p>Diffusion of drug from gel (B)</p> Signup and view all the answers

    Which functional groups are primarily involved in the adhesion of mucoadhesive polymers to mucosal surfaces?

    <p>Hydrogen-bonding functional groups (B)</p> Signup and view all the answers

    What is a common example of a polymer used for mucoadhesive drug delivery?

    <p>Polyethylene oxide (C)</p> Signup and view all the answers

    What is a primary medical reason for needing controlled drug delivery?

    <p>To ensure optimal dosing at the correct time and location (D)</p> Signup and view all the answers

    What is a societal benefit of controlled drug delivery systems?

    <p>Improved patient comfort and standard of living (B)</p> Signup and view all the answers

    Which of the following accurately describes lithium ion therapy for manic depression?

    <p>It poses a risk of toxicity due to a narrow therapeutic window (A)</p> Signup and view all the answers

    What is a potential disadvantage of current drug delivery methods that controlled drug delivery aims to improve?

    <p>They may involve inefficient use of active ingredients (A)</p> Signup and view all the answers

    What is one characteristic of 'smart' or responsive polymers in drug delivery?

    <p>They react to stimuli to enable dynamic release of drugs (C)</p> Signup and view all the answers

    What characterizes monolithic devices in drug delivery?

    <p>They are typically made by mixing polymer and drug. (C)</p> Signup and view all the answers

    How is the drug release controlled in reservoir devices?

    <p>By diffusion control. (D)</p> Signup and view all the answers

    What is the primary role of leachable additives in polymer drug delivery systems?

    <p>To render the polymer porous for drug diffusion. (D)</p> Signup and view all the answers

    What distinguishes polymer drug conjugates in drug delivery?

    <p>They use a polymer attached to the drug through a covalent bond. (D)</p> Signup and view all the answers

    Which method is used to create microencapsulated polymers?

    <p>Interfacial polycondensation. (D)</p> Signup and view all the answers

    What is one common application of biodegradable polymers in drug delivery?

    <p>They degrade in vivo to release the drug. (B)</p> Signup and view all the answers

    What is a factor that complicates the use of biodegradable polymers in drug delivery?

    <p>Challenges in controlling the degradation rate. (D)</p> Signup and view all the answers

    What role does sodium alginate play in drug delivery systems?

    <p>It is used to create capsules through gelation. (B)</p> Signup and view all the answers

    Flashcards

    Controlled Drug Delivery

    A method to release drugs at specific rates and locations for optimum effect.

    Advantages of Targeted Release

    Improved therapy outcomes, reduced side effects, and increased patient comfort.

    Smart Polymers

    Polymers that respond to specific stimuli to control drug release.

    Inositol Monophosphatase in Manic Depression

    An enzyme linked to manic depression treatment via lithium ions, needing controlled delivery.

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    Lithium Ion Therapy

    Current treatment for manic depression with a narrow therapeutic window, risk of toxicity.

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    Biodegradable Polymers

    Polymers that are metabolized in the body, leaving no trace.

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    Chemical Synthesis

    Process of creating biodegradable polymers using chemical reactions.

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    Hydrogels

    Three-dimensional, hydrophilic polymeric networks used in drug delivery.

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    Mucoadhesives

    Polymers designed to adhere to mucus membranes for drug delivery.

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    Drug Release Modes

    Mechanisms include diffusion from gel and active efflux.

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    Monolithic devices

    Films with drug embedded in a polymer matrix; easy to fabricate.

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    Reservoir devices

    Drugs are contained by polymers; release is diffusion-controlled.

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    Fickian diffusion

    Model predicting how substances diffuse through membranes.

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    Leachable additives

    Polymers release drugs through hydrophilic components diffusing out.

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    Polymer drug conjugates

    Drugs bonded to a polymer via a covalent linker.

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    Microencapsulation

    Encapsulation of active therapeutics in polymer capsules.

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    Interfacial polycondensation

    Polymer forms at boundary of two phases.

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    Active site accessibility

    The location in the body where a drug exerts its effect.

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    Drug concentration issues

    Drugs may not reach the desired concentration at the active site, leading to inefficacy.

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    Controlled release benefits

    Maintaining drug levels within a desired range for efficiency and fewer doses.

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    Difficult drugs

    Drugs that are challenging to deliver effectively due to solubility issues.

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    Poorly-soluble drugs

    Drugs like Danazol that can be encapsulated to improve solubility.

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    Polymers

    Large molecules composed of sub-units that can protect therapeutic compounds.

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    Natural polymers

    Polymers derived from natural sources like seaweeds and plants.

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    Gene therapy barriers

    Challenges that nucleic acids face, such as degradation by nucleases.

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    Biocompatible vector

    A carrier that is safe for the body and can deliver drugs.

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    Endocytosis

    A process by which cells take in materials by engulfing them.

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    EPR effect

    Enhanced permeability and retention, allowing polymer-drug uptake in tumors.

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    Thermosensitive hydrogels

    Polymers that change properties with temperature for drug delivery.

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    Intracellular delivery requirements

    Features needed for effective drug delivery within cells.

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    Fick's First Law

    Flux is proportional to the concentration gradient across a membrane.

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    Fick's Second Law

    Describes how concentration changes in a membrane over time.

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    Lysosomal enzymes

    Enzymes in lysosomes that digest cellular waste and foreign material.

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    Study Notes

    Controlled and Site-Specific Drug Delivery

    • Controlled drug delivery is necessary for optimal dose, timing, and location
    • Disadvantages of current methods include drug not reaching active site, wasteful use, potential for toxic responses at other sites, inadequate drug concentration at active site, excessive cost, and/or ineffective dosage.
    • Advantages of new methods include maintaining drug levels within a range, improved efficiency, fewer administrations, and enabling delivery of "difficult" drugs. These include slow-release water-soluble drugs and fast-release low-solubility drugs.
    • Examples of poorly soluble drugs include Danazol (pituitary gonadotropin inhibitor) which can be solubilized using beta-cyclodextrin.
    • Peptides and proteins, such as insulin, require controlled delivery in vivo due to proteolysis and poor bioavailability.
    • Nucleic acids require controlled delivery due to degradation by exo- and endo nucleases (important for gene therapy).

    Polymer-based delivery systems

    • Current polymer uses include polymer therapeutics for in situ drug release.
    • "Smart" or responsive polymers allow for pharmaceutical targeting and dynamic release.
    • Imprinted polymers represent potential new release systems.

    Why controlled drug delivery is necessary?

    • Medical reasons – precise dosage at the right time and location for optimal effect.
    • Industrial reasons – efficient use of expensive ingredients to reduce production costs.
    • Societal reasons – improved patient comfort, better therapy, and overall quality of life.
    • Case Study: Inositol Monophosphatase and Manic Depression. Manic depression affects 1% of the population. Inositol Monophosphatase is an enzyme that is overactive in manic depression. Lithium ion therapy is the current treatment, but it has a narrow therapeutic window (0.8- 1.2mM). Lithium ions are extremely toxic at 2 mM. New IMPase inhibitors are being developed.

    Disadvantages of current methods

    • The drug does not reach the active site, leading to waste and potential toxicity at other sites.
    • The drug does not reach the active site in the desired concentration.
    • Current methods are often expensive and/or ineffective at the applied dose.

    Advantages of new methods

    • Maintenance of drug levels within a desired range.
    • Efficient delivery with fewer administrations needed.
    • Improved delivery of "difficult" drugs, like slow-release water-soluble drugs or fast-release low-solubility drugs.

    What is a polymer and how can they help

    • A polymer is a large molecule composed of multiple sub-units (natural, e.g. alginates, or synthetic, e.g. poly(HMPA)).
    • Function is governed by the number and arrangement of constitutional repeat units (e.g. -[A-], -[A-B-], etc).
    • They are made by processing natural products (e.g., alginates from seaweeds) and by synthesis from chemical feedstocks (e.g., poly(olefins) or nylons).
    • Polymers can help by protecting therapeutic compounds during passage through the body and acting as mediators/activators for controlled release

    Examples of polymers in drug delivery

    • Monolithic devices: Films with the drug in a polymer matrix (easy to fabricate).
    • Reservoir devices: Drug is contained by the polymer (release is usually diffusion-controlled).
    • Leachable additives: Polymer contains drug and a second component. This component diffuses out, creating porosity and allowing drug release.
    • Polymer drug conjugates: Polymer attached to the drug by a linker (used for drugs needing modifications/enhancements).

    Examples of polymers in Drug delivery Microencapsulation:

    • Polymer capsules can contain active therapeutics (natural or synthetic polymers).
    • Widely used in various industries, e.g., for fragrance release, flavor masking.
    • Different encapsulation methods exist, such as interfacial polycondensation or controlled gelation in an aqueous solution.
    • Drug release can occur through physical disruption of the capsules or diffusion through porous membranes.

    Examples of biodegradable polymers

    • Biodegradable polymers degrade in vivo to release the drug.
    • Simple mechanism, but fine control over degradation is difficult.
    • These polymers don't trigger inflammatory or toxic responses.
    • Common biodegradable polymers: Poly(lactide-co-glycolide) (PLGA), Poly(hydroxybutyrate-co valerate) (Biopol)..
    • Synthesis methods: Chemical synthesis and bacterial biosynthesis (Biopol).
    • Examples in use: Dexon (poly(glycolide)), Vicryl (PLGA).

    Polymers for oral delivery - hydrogels

    • Major class of polymer drug delivery vehicles, three-dimensional, hydrophilic polymeric networks, swollen with water.
    • Cross-linking between polymer chains determines swelling behaviour and gel flexibility.
    • Natural or synthetic, with a wide range of applications.
    • Inherently biocompatible and strongly hydrated. Made e.g. with 2-hydroxyethylmethacrylate (HEMA)
    • Drug release is facilitated by diffusion from the gel or by active efflux.

    Polymers for oral delivery - mucoadhesives

    • Similar to hydrogels but are designed for localization at mucus membranes.
    • Can be used in situations requiring adhesive interactions to mucosal surfaces.
    • Inherently biocompatible and strongly hydrated. Examples are made with methacrylic acid and poly(ethylene oxide).
    • Drug release is enabled through diffusion or activation by pH or hydration changes.

    Thermosensitive hydrogels in drug delivery

    • These hydrogels alter their properties based on temperature changes.
    • Examples have a core of Calcium carbonate, drug layer, thermosensitive membrane (Ethylcellulose), and nanoparticles and voids.
    • The shape (and thus drug release) changes depending on the temperature.

    Polymers for cancer therapy

    • Biocompatible vectors are required for intracytoplasmic delivery of therapeutics.
    • Must protect against biodegradation and metabolism; avoid rapid liver uptake.
    • Need functionality for targeting appropriate cells and ability to enter cells via endocytosis, exit endosomes, traffic through cytoplasm to target organelles, and deliver drug using a suitable mechanism.

    The Enhanced Permeability and Retention (EPR) effect

    • Tumor tissues possess characteristics that enhance the delivery of targeted polymer-drug conjugates, enabling selective uptake.
    • This effect is due to enhanced permeability and retention of the polymer conjugate.

    Biomolecular recognition systems

    • Host-guest interactions are crucial in many biological systems, enabling specific recognition and binding.
    • Molecules (host) which bind and recognize other molecules (guest).
    • Examples include enzymes, antibodies, lectins, and cells interacting with their substrate, cofactors, inhibitors, antigens, sugars etc.

    "Smart" or responsive polymers

    • Macromolecule capable of a non-linear response to an external stimulus (e.g., temperature, pH, magnetic or electric fields).
    • Used for various functions in biotechnology and medicine.
    • Examples of these polymers include PEO/PPO co-polymers, PVA/PAA co-polymers, PNIPAm/PAA co-polymers.

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