Alzet Pumps - Overview

ALZET® Pumps - Overview

ALZET Osmotic Pumps are miniature, implantable pumps for research in mice, rats, and other laboratory animals.

These minipumps deliver drugs, hormones, and other test agents at continuous and controlled rates, for durations ranging from one day to six weeks, without the need for external connections or frequent handling. Their unattended operation eliminates the need for repeated nighttime or weekend dosing by lab personnel.

ALZET minipumps can be used for systemic administration when implanted subcutaneously or intraperitoneally. They can be attached to a catheter for intravenous, intracerebral, or intra-arterial infusion. ALZET pumps can also be used for targeted delivery, where the effects of a drug or test agent are localized in a particular tissue or organ, by means of a catheter. 


ALZET pumps have been used to target delivery to a wide variety of sites including the spinal cord, spleen, liver, organ or tissue transplants, and wound healing sites. ALZET pumps have been used in thousands of studies on the effects of controlled delivery of a wide range of experimental agents, including peptides, growth factors, cytokines, chemotherapeutic drugs, addictive drugs, hormones, steroids, and antibodies. Due to the unique  mechanism (shown below) by which ALZET pumps operate, compounds of any molecular conformation can be delivered predictably at controlled rates, independent of their physical and chemical properties. A bibliography (external link) of pump work which has been documented in the scientific literature is available, as is information on the osmotic delivery mechanism of ALZET pumps.

ALZET pumps are intended for use in experimental animals only. They are not to be placed into animals used for food products. They are not to be used in humans.

How does it work

ALZET pumps operate because of an osmotic pressure difference between a compartment within the pump, called the salt sleeve, and the tissue environment in which the pump is implanted. The high osmolality of the salt sleeve causes water to flux into the pump through a semipermeable membrane which forms the outer surface of the pump. As the water enters the osmotic layer, it compresses the flexible reservoir, displacing the test solution from the pump at a controlled, predetermined rate. Because the compressed reservoir cannot be refilled, the pumps are designed for single-use only. The rate of delivery by an ALZET pump is controlled by the water permeability of the pump’s outer membrane. Thus, the delivery profile of the pump is independent of the drug formulation dispensed. Drugs of various molecular configurations, including ionized drugs and macromolecules, can be dispensed continuously in a variety of compatible vehicles at controlled rates. The molecular weight of a compound, or its physical and chemical properties, has no bearing on its rate of delivery by ALZET pumps.

The volume delivery rate of ALZET pumps is fixed at manufacture. ALZET Osmotic Pumps are available with a variety of delivery rates between 0.11 and 10 μL/hr and delivery durations between 1 day and 6 weeks. While the volume delivery rate of the pump is fixed, different dosing rates can be achieved by varying the concentration of agent in the solution or suspension used to fill the pump reservoir. 

A more complete and technical explanation of the operation of ALZET osmotic pumps can be found in the following reference:

Theeuwes F and Yum SI. Principles of the design and operation of generic osmotic pumps for the delivery of semisolid or liquid drug ormulations. Ann Biomed Eng 1976, 4(4):343-353.

ALZET® is a registered trademark of DURECT Corporation

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