Video summary

Week 01: Lecture 02: Fundamentals of Drug Delivery Systems-II

Main summary

Key takeaways

Educational

Main Ideas, Concepts, and Lessons

Purpose of the Course/Lecture

  • Recap (from the previous lecture): Novel drug delivery systems
    • Definitions
    • Conventional vs. novel differences
    • Evaluation methods and terminology
  • Today’s focus:
    • Additional drug delivery terminologies
    • Advantages and limitations
    • Generations of drug delivery systems

Key Drug Delivery Terminology Mentioned

1) Therapeutic Range

  • Drug concentrations must be kept within an effective concentration range to achieve the desired therapeutic effect.

2) Control Release / Sustained / Extended Release Concepts

  • Core goal: maintain drug action at the right level over time.
  • The lecture references converting formulations so the drug shows controlled release behavior (including a “zero order” concept).
  • In practical settings, extended release and related terms are commonly used.

3) Nanocarrier Systems

  • Presented as another major terminology, with dedicated future coverage.
  • Definition/role:
    • Nanocarriers (also called vehicles) use nano-scale materials to transport drug molecules:
      • from the administration site
      • to the disease site
  • Types/categories:
    • Polymer-based
    • Lipid-based, including:
      • liposomes
      • solid lipid nanoparticles
      • vesicular systems
    • Inorganic/metal nanoparticle–based
    • Hybrid systems combining polymer + lipid
  • Size concept:
    • Typically in the 1 to 1,000 nanometer range.
  • Benefits claimed:
    • Higher drug loading
    • Improved penetration/permeability
    • Delivery to the “right site”
  • Related term:
    • “Nano medicines” is used interchangeably in this context.
  • Examples mentioned:
    • Liposomes
    • Dendrimers
    • Micelles (prepared using surfactants and/or polymers)

Targeted Drug Delivery Systems

Why Targeting Is Needed

  • Conventional delivery is largely non-specific: drugs reach normal cells as well.
  • This is especially problematic for chemotherapy, since anti-cancer drugs are toxic and may damage healthy cells too.

Targeting Strategies

  • Active targeting
  • Passive targeting

Intended Outcome

Deliver the drug moiety to:

  • a specific organ
  • a specific tumor
  • specific cells
  • potentially subcellular levels / even organelles

Result: reduce non-specific toxicity.

Examples of Chemotherapy Side Effects Listed

  • Bone marrow depression
  • Alopecia (hair loss)
  • Anorexia (loss of appetite)

EPR Effect (Enhanced Permeability and Retention)

  • Tumors often have:
    • leaky vasculature
    • reduced lymphatic drainage
  • Nano-range carriers can:
    • enter tumor tissue
    • remain and accumulate
  • This is a tumor microenvironment–driven phenomenon supporting targeted delivery.

Advantages of Novel Drug Delivery Systems vs. Conventional Systems

  • Improved therapeutic efficacy
    • Depends on formulation strategy.
    • For water-insoluble or low-permeable drugs, novel systems can improve:
      • solubility
      • permeability
      • bioavailability
    • Targeting can further improve delivery to the target site.
  • Reduced degradation
    • Encapsulation/coating can protect drugs from degradation.
  • Time-based and prolonged/modified release
    • Polymers can enable controlled/prolonged release.
  • Reduced dose frequency
    • Long-acting formulations may reduce how often patients take doses (illustrated by comparison with twice-daily dosing in a diabetes scenario).
    • Goal: improved patient compliance.
  • Reduced side effects
    • Achieved via targeting, controlled release, and optimized drug exposure.
  • Improved pharmacokinetic profile / bioavailability
    • Relates to ADME:
      • Absorption, Distribution, Metabolism, Excretion
    • Improved absorption generally improves bioavailability.
  • Protection under harsh conditions
    • pH-sensitive and temperature-sensitive polymers can prevent premature drug release.
    • Example: avoid release in stomach acidic conditions and shift release toward intestinal/colonic pH.

Methodology / List-Style Instructions (From Subtitles)

Conceptual Steps/Considerations for Developing Novel Delivery Systems

  • Maintain drug levels within the therapeutic range.
  • Convert the formulation to achieve controlled/modified release behavior
    • (framed with “zero order” control-release ideas).
  • If targeting or improved performance is needed:
    • Consider nanocarrier selection (polymer/lipid/hybrid/inorganic)
    • Choose targeting type:
      • Active or Passive
    • For tumor accumulation, use mechanisms such as EPR (nano-size + tumor leakiness + retention).
  • For low-solubility/low-permeability drugs:
    • Improve solubility and permeability to raise bioavailability.
  • To reduce degradation:
    • Use coatings/encapsulation strategies.
  • For drugs needing longer serum/plasma presence:
    • Choose polymers enabling time-based control / prolonged release.
  • For GI/oral delivery design:
    • Study GI residence time (performance depends on how long the dosage form remains available).
  • For environment-sensitive release:
    • Use pH-sensitive / temperature-sensitive polymers to control where release happens.

Limitations (Explicitly Listed in the Subtitles)

  • Delayed onset of drug action
    • If action is delayed too much, the approach may fail to treat the disease effectively.
  • Dose dumping risk
    • Poor formulation strategy can cause rapid release of a large drug amount over a short period.
  • Dependence on GI residence time (for oral/GI-dependent delivery)
    • Efficacy may vary based on how long the dosage form stays in the GI tract.
  • Less accurate dose adjustment in some cases
    • When switching from conventional to novel/nano systems:
      • dose calculations must be accurate
      • release changes affect delivered exposure and efficacy
  • Higher cost per unit dose
    • New materials and manufacturing increase:
      • raw material cost
      • manufacturing/maintenance expenses
    • Therefore costs can exceed conventional dosing.
  • Not all drugs are suitable for extended/modified release
    • A system won’t fit every drug; properties must match the intended delivery design.
    • (The lecture notes future classes will cover properties needed for control release and formulation selection, including for nanocarriers.)

Generations of Drug Delivery Systems (5 Generations)

First Generation (Conventional Systems)

  • Includes: capsules, tablets, emulsions, suspensions
  • Characteristics/limitations mentioned:
    • Low efficacy
    • Low safety
    • Not targeted
    • Maximum side effects (as stated)

Second Generation (Modified Action Systems)

  • Examples:
    • Enteric-coated systems (release in intestinal pH)
    • Prolonged action systems
  • Rationale:
    • Protect pH-sensitive biological molecules from acidic conditions
  • Outcome:
    • Improved efficacy (as stated)

Third Generation (Control Drug Delivery Systems)

  • Examples:
    • Osmotically swelling
    • Diffusion control systems
  • Mechanistic idea:
    • Use polymers to enable controlled delivery

Fourth Generation (Targeted Delivery Systems)

  • Aim:
    • Deliver formulation to a particular site
  • Can use:
    • carriers including nano formulations
  • Claimed benefit:
    • Efficacy can improve

Fifth Generation (Advanced / Nano + Gene Therapy Systems)

  • Includes:
    • Nano-bots
    • Gene therapy
    • Long-term delivery systems
  • Long-term delivery duration stated:
    • 6 to 12 months
  • Modern biotech approaches mentioned:
    • CRISPR technology
    • Exosomes
    • mRNA vaccines
  • Framing:
    • Evolution driven by limitations of earlier generations

Speakers / Sources Featured

  • Dr. Dr. Satish Dawanapili (Asant)
    • Professor, Department of Pharmaceutical Sciences and Technology
    • Institute of Chemical Technology (ICT), Mumbai
    • Lecturer speaking throughout
  • YouTube video (course lecture): Week 01: Lecture 02: Fundamentals of Drug Delivery Systems-II
    • (Host/source implied by the NPDL online certification course context)

Original video