Transport Mechanisms of Drugs Across Cell Membrane

Transport of Drugs Across Plasma Membrane

Overview

Drug transport across the plasma membrane is essential for effective drug delivery in the body. The process can be categorized into both passive and active mechanisms.

Mechanisms of Drug Transport

1. Passive Diffusion
   • Definition: Movement of drug molecules from an area of high concentration to an area of low concentration without energy usage.
   • Insights: Most common method for lipid-soluble drugs. No energy is required, making it a relatively fast process.
2. Filtration
   • Definition: Movement through membrane pores along with water molecules.
   • Insights: Depends on hydrostatic pressure or osmotic forces. Important for small, water-soluble molecules.
3. Specialized Transport
   • Involves other mechanisms requiring specific pathways or energy.

Specialized Transport Types

• Carrier Mediated
  • Facilitated Diffusion
    • Definition: Movement via specific carrier proteins without energy.
    • Insights: Used for molecules that cannot diffuse freely across the membrane.
  • Active Transport
    • Definition: Movement against a concentration gradient, requiring energy (ATP).
    • Primary Active Transport: Direct use of energy for transport.
    • Secondary Active Transport: Utilizes the energy from the electrochemical gradient built by primary active transport.
• Vascular Transport
  • Endocytosis
    • Definition: Process of cellular uptake by engulfing particles using membrane invagination.
    • Insights: Used for large molecules or particles.
  • Exocytosis
    • Definition: Process of vesicles fusing with the plasma membrane to release contents outside the cell.
    • Insights: Common in neurotransmitter release at synaptic junctions.

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Extended readings: