Background

Since the 1960's, Alza Corporation has been developing drug delivery techniques and devices that enhance the value of particular drugs by improving on their efficacy and safety.  In 1998, Alza developed a new technology around which an entire company was formed.  This device, called Duros, is a small, matchstick sized, osmotic pump that resides just underneath the patient's skin.  The size of the device and the fact that it can deliver a dose for up to 1 year after insertion, makes it an appealing device for patients and physicians alike.  Through osmotic forces, water is drawn into the device through a semi-permeable membrane into a salt engine.  Without the use of batteries or switches, the internal pressure builds in this cavity until a piston is moved, dispensing drug out the opposite end of the device.  This technology known as Duros was eventually licensed to a spin off from Alza called Durect Corporation.

Challenge

During the development of the technology, Speck Design was brought into Alza to mechanically design the device.  Speck Design worked on the geometry of the device along with its fit and finish.  Catheterized versions presented its own set of additional challenges.  The process entailed creating prototypes which were then tested.  Speck Design also participated in FMEA reviews at Alza and worked to minimize and eliminate particular failure modes.

Solution

When Durect announced the Duros System, they introduced a device that presented a slew of attractive features.  More specificaly, the device has an unmatched dose delivery precision.  As opposed to conventional dosing, there is no delivery spike.  The dose meters out in the beginning at the same rate as the very end of the dose.  The internal pressures are large enough that drugs of very high viscosity can be delivered.

Results

The end result was a device that can accurately deliver a dose as small as 0.5 microliter a day.  That is less than 1/100th the amount in a single drop of water per day.  The device was later cleared by the FDA as a treatment for prostate cancer.

PROJECT INFO

• Client:

  Durect Corporation

• Project:

  Drug Delivery Pump

• Industry:

  Medical