Osmotic Pump
- S-7-NOVEL DRUG DELIVERY SYSTEMS
- Nov 15, 2024
- 2 min read
Updated: Jan 23
Osmotic Pumps
Osmotic pump systems utilize osmotic pressure to control drug release rates, offering precise and predictable drug administration.

Principle
Osmotic pumps rely on osmosis, where water enters through a semi-permeable membrane, creating pressure that pushes the drug out through a small orifice at a controlled rate.
Key Components
Semi-Permeable Membrane: Allows water entry, restricting solute passage.
Drug Reservoir: Contains the drug, often mixed with an osmotic agent.
Osmotic Agent: Increases internal pressure for drug release.
Delivery Orifice: Controls the release rate of the drug.
Mechanism:
Osmotic Gradient:
An osmotic agent within the pump draws water into the device through a semi-permeable membrane.
Drug Release:
The influx of water creates pressure that pushes the drug out through a delivery orifice at a controlled rate.
Zero-Order Kinetics:
Provides a constant drug release rate, independent of external conditions.
Types of Osmotic Pumps:
1) Push-Pull Osmotic Pump:
Structure: Contains two compartments; one with the drug and osmotic agent, and the other with a polymer.
Mechanism: The osmotic agent draws water into the drug compartment, pushing the drug out.
2) Elementary Osmotic Pump:
Structure: Simpler design with a single compartment containing the drug and osmotic agent.
Mechanism: Direct water influx drives drug release through the membrane.
3) Tablet-Based Osmotic Systems:
Structure: Incorporate osmotic agents and are coated with semi-permeable membranes.
Mechanism: Water entry and osmotic pressure facilitate drug egress at a controlled rate.
Examples
Oral Systems: OROS tablets for controlled GI drug release.
Implantable Systems: DUROS implants for long-term, localized delivery (e.g., leuprolide for cancer).
Advantages of Osmotic Pumps:
Precise Control: Achieves zero-order release kinetics, ensuring steady drug levels.
Independence from External Factors: Release rate is unaffected by environmental pH, temperature, or mechanical forces.
Predictable Performance: High reproducibility and reliability in drug release profiles.
Disadvantages of Osmotic Pumps:
Complex Manufacturing: Requires precise engineering and materials.
Limited to Certain Drugs: Primarily suitable for drugs that can be formulated within the osmotic system without instability.
Potential for Mechanical Failure: Risk of membrane rupture or blockage affecting drug release.