Improving Bioavailability of Poorly Soluble Drugs
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What happens to the drug in SDDS after it comes into contact with GI fluids?

  • It remains in a supersaturated concentration
  • It forms a micelle
  • It precipitates out of the solution
  • It springs into the system and then slowly returns (correct)

    • What is the role of polymers in SDDS?

  • To form a micelle with the surfactant
  • To enhance the lipophilicity of the drug
  • To increase the viscosity of the solution
  • To prevent precipitation of the drug (correct)

    • What is the name of the cancer drug that is dissolved in PEG 400?

  • Bexarotene (correct)
  • Voriconazole
  • Etoposide
  • Ethosuximide

    • What is the purpose of cosolvents in improving bioavailability?

    <p>To dissolve the drug in a solvent</p> Signup and view all the answers

    What is the result of micellar solubilization?

    <p>An improvement in the solubility of the drug</p> Signup and view all the answers

    What is the composition of cyclodextrins?

    <p>Cyclic oligosaccharides</p> Signup and view all the answers

    What is the purpose of using surfactants in micellar solubilization?

    <p>To facilitate the formation of micelles</p> Signup and view all the answers

    What is the result of drug precipitation in SDDS?

    <p>Large variability in bioavailability</p> Signup and view all the answers

    What is the final form of the drug in SEDDS after it comes into contact with aqueous medium?

    <p>Micro-emulsion</p> Signup and view all the answers

    What is the primary purpose of BA/BE studies in drug development?

    <p>To assess the safety and efficacy of a drug product in clinical trials</p> Signup and view all the answers

    What is the primary purpose of assessing bioavailability?

    <p>To determine the rate of drug absorption</p> Signup and view all the answers

    What is the assumption made in urinary excretion curve studies?

    <p>No drug metabolism before reaching systemic circulation</p> Signup and view all the answers

    What type of studies are needed for INDs, NDAs, ANDAs, and their amendments and supplements?

    <p>BA and/or BE studies</p> Signup and view all the answers

    What is the formula to calculate absolute bioavailability?

    <p>AUCTabs / AUCTiv</p> Signup and view all the answers

    What can be estimated from BA studies?

    <p>The fraction of dose absorbed from an orally administered drug product</p> Signup and view all the answers

    What is the purpose of relative bioavailability studies?

    <p>To compare the bioavailability of a test dosage form to a standard dosage form</p> Signup and view all the answers

    What is the purpose of BE studies in ANDA submissions?

    <p>To establish bioequivalence between the test drug and the RLD</p> Signup and view all the answers

    What affects the bioavailability of a drug?

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

    When are BE studies necessary?

    <p>When there are changes in the manufacturing or formulation of a drug product</p> Signup and view all the answers

    What is the purpose of bioequivalence studies?

    <p>To compare the bioavailability of different dosage forms</p> Signup and view all the answers

    What is the recommended approach for bioequivalence studies as per FDA guidelines?

    <p>Accurate, sensitive, and reproducible approaches</p> Signup and view all the answers

    What is the purpose of documenting BE?

    <p>To ensure product quality throughout the shelf life of a drug product</p> Signup and view all the answers

    What is the assumption made in plasma concentration-time curve studies?

    <p>No residual concentration and residual effects</p> Signup and view all the answers

    When is a BE study required?

    <p>When there are changes in the manufacturing or formulation of a drug product</p> Signup and view all the answers

    What is the purpose of assessing the urinary excretion curve?

    <p>To determine the rate and extent of drug absorption</p> Signup and view all the answers

    What is the classification of drugs based on?

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

    What is the primary focus of BA studies?

    <p>Pharmacokinetic information related to drug ADME in vivo</p> Signup and view all the answers

    Which of the following conditions may waive the requirement for in vivo BA or BE?

    <p>Solutions that are self-evident in their bioavailability</p> Signup and view all the answers

    What is the main requirement for a solution to be considered self-evident in its bioavailability?

    <p>It contains the active ingredient in the same concentration and dosage form as another approved drug product</p> Signup and view all the answers

    What is the purpose of referencing 21 CFR 320.21 in regulatory requirements?

    <p>To outline the general considerations for bioequivalence testing</p> Signup and view all the answers

    What type of drug product may be considered self-evident in its bioavailability based on its route of administration?

    <p>Parenteral solutions administered by injection</p> Signup and view all the answers

    What is a key consideration for a solution to be considered self-evident in its bioavailability?

    <p>It contains no inactive ingredients that may affect absorption</p> Signup and view all the answers

    What type of evidence may be relied upon for certain drug products according to 21 CFR 320.22?

    <p>In vitro evidence</p> Signup and view all the answers

    What is the purpose of referencing 21 CFR 320.22 in considerations for bioequivalence?

    <p>To outline the requirements for determining in vivo BA and BE</p> Signup and view all the answers

    What is an example of a drug product that may be considered self-evident in its bioavailability?

    <p>A solution administered through inhalation as a gas</p> Signup and view all the answers

    What is a key condition for a biowaiver based on BCS?

    <p>The drug product is a solid oral dosage form with high solubility</p> Signup and view all the answers

    What is the primary site of drug metabolism in the liver?

    <p>SER of hepatocytes</p> Signup and view all the answers

    What is the name of the largest family of membrane-bound, non-specific, multifunctional enzymes involved in drug metabolism?

    <p>P450 system</p> Signup and view all the answers

    What is the result of the action of the mono-oxygenase system in drug metabolism?

    <p>Both oxygen is reduced and substrate is oxidized</p> Signup and view all the answers

    Which phase of drug metabolism involves the passage of drugs across the plasma membrane?

    <p>Phase 0</p> Signup and view all the answers

    What is the primary function of Phase 1 reactions in drug metabolism?

    <p>To introduce a reactive group</p> Signup and view all the answers

    Which of the following enzymes is NOT involved in Phase 1 reactions?

    <p>Glucuronyl transferases</p> Signup and view all the answers

    What is the primary function of Phase 2 reactions in drug metabolism?

    <p>To transfer a polar group</p> Signup and view all the answers

    What is the role of influx transporters in drug metabolism?

    <p>To facilitate the passage of drugs across the plasma membrane</p> Signup and view all the answers

    Which of the following is NOT a type of enzyme involved in Phase 1 reactions?

    <p>Glucuronyl transferases</p> Signup and view all the answers

    Study Notes

    Improving Bioavailability of Poorly Soluble Drugs

    • Factors affecting bioavailability: lipophilicity, cosolvents, cyclodextrins, micellar solubilization, and self-emulsifying drug delivery systems (SEDDS)
    • Cosolvents: low molecular weight, e.g., PEGs, PG, Glycerol, to dissolve drugs in soft gel capsules
    • Examples of cosolvent-based formulations: Bexarotene (Targretin), Etoposide (VePesid), Ethosuximide (Zarontin)

    Cyclodextrins

    • Cyclic oligosaccharides composed of glucopyranose units
    • Lipophilic molecules trapped inside cyclodextrins to increase aqueous solubility
    • Example: Voriconazole (antifungal drug)

    Micellar Solubilization

    • Surfactants used to improve solubility of drugs, increasing bioavailability
    • Used for both liquid and solid formulations

    Self-Emulsifying Drug Delivery Systems (SEDDS)

    • Drug solubilized in oil/surfactant vehicle, filled in a soft gelatin capsule
    • Micro-emulsion or nano-emulsion results, with drug diffusing into the aqueous medium

    Biopharmaceutical Properties

    • Drug release, stability, permeability, and measurement of bioavailability
    • Factors affecting bioavailability: pre-systemic metabolism, permeability, and release of drug

    Assessment of Bioavailability

    • Plasma concentration-time curve: measures rate and extent of absorption
    • Urinary drug excretion curve: measures rate and extent of elimination
    • Bioavailability: fraction of administered dose that reaches systemic circulation
    • Absolute bioavailability: compares bioavailability of a drug via different routes of administration
    • Relative bioavailability: compares bioavailability of a drug via different formulations

    Bioequivalence Studies

    • Important for drug development and regulatory approval
    • Types of bioequivalence studies: in vivo, in vitro, and clinical trials
    • Approaches: comparative pharmacokinetic studies, pharmacodynamic studies, clinical trials, and in vitro tests

    Regulatory Requirements

    • Refer to 21 CFR 320.21 for guidelines on bioavailability and bioequivalence studies
    • Waivers: certain circumstances where bioavailability or bioequivalence studies may be waived

    Considerations

    • Self-evident bioavailability: certain drug products where bioavailability is obvious
    • Biowaivers: certain situations where bioavailability studies may not be required

    Drug Metabolism and Excretion

    • Phases of metabolism: 0, 1, 2, and 3
    • Phase 1: introduction of reactive groups, e.g., oxidation, hydrolysis
    • Phase 2: transfer of polar groups, e.g., glucuronidation, sulfation
    • Phase 3: transport outside, e.g., efflux transporters

    Phase I Reactions

    • Enzymes: oxygenases/oxidases, e.g., CYP450 isozymes, flavin-containing monooxygenases
    • Examples of Phase I reactions: hydrolysis, oxidation, reduction, and cyclization

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    Biopharmaceutics & Pharmacokinetics Lecture 6 PDF

    Description

    This quiz explores the factors affecting bioavailability of poorly soluble drugs due to lipophilicity, including SDDS and SEDDs methods.

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