Digestive tract disorders such as Crohn's disease, colitis and
colon cancer are becoming increasingly common, particularly in the
western world. Crohn’s disease and colitis can be treated with
drugs, notably steroids, but many of these drugs have adverse and
unpleasant side effects for patients when administered systemically
as whole-body doses. However, by delivering the required drugs
directly to the site of disease, dose levels may be lowered and many
of these side effects could be reduced.
It is this need for accurate delivery of drugs to specific sites in
the intestinal tract that drove the development of Philips
Research’s intelligent pill “iPill” for electronically controlled
drug delivery. In addition to the potential benefits of this new
technology to improve patient therapy, the iPill promises to be a
valuable research tool for the development of any new drug that is
delivered via the intestinal tract.
Capsules containing ultra-miniature cameras are already in use as
diagnostic tools, but lack the ability to deliver drugs. The
challenge for scientists at Philips Research was to find a way of
navigating a drug-loaded pill capsule to the site of disease and
then releasing a metered amount of drug into the gut at that
location.
The mechanical design of Philips Research’s intelligent pill
(iPill). In the form of an 11 x 26 mm capsule, the iPill
incorporates a microprocessor, battery, pH sensor,
temperature sensor, RF wireless transceiver, fluid pump and
drug reservoir.
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Navigating the gut
What Philips Research has developed is a pill that can be swallowed
with food or water in the normal way and is then carried along by
the normal movement of food through the gut. Knowing where the iPill
is in the gut relies on the fact that the gut’s pH value (a measure
of acidity) rises sharply upon exiting the stomach and becomes
progressively alkaline from the upper intestine onwards. In
addition, there is typically a noticeable drop in pH between the
small intestine and the colon. Armed with pH information, which is
measured by the iPill itself, and data about typical transit times
through the gut, the iPill’s location in the gut can be determined
with good accuracy. Where greater accuracy is required, external
medical imaging equipment could be introduced. Locations where the
drug needs to be released could also be determined by medical
imaging – for example, endoscopy, MRI or CT scans.
Programmable drug release profiles
In the form of an 11 x 26 mm capsule, the iPill incorporates a
microprocessor, battery, pH sensor, temperature sensor, RF wireless
transceiver, fluid pump and drug reservoir. It communicates via its
wireless transceiver to a control unit outside the body.
Localized drug delivery is performed by the iPill’s internal pump
under the control of the microprocessor, allowing accurate control
of the drug delivery profile. Examples of possible delivery profiles
include a burst, progressive release or a multi-location dosing.
Pre-planning can be used to determine the target location for drug
delivery and hence to define a control program for the
microprocessor. This program is loaded into the iPill before it is
swallowed, where it controls execution of the drug delivery profile
in response to pH measurements taken as the iPill moves through the
gut. Further data from the iPill, such as its temperature
measurements, are reported wirelessly to an external control unit,
which records data and may also transmit additional control signals
back to the iPill.
Current status
Philips Research has constructed a prototype iPill capsule and
system. The design of iPill is suitable for serial manufacturing.
The iPill contains all the components described above and
miniaturization was made possible by advanced electronic and
mechanical integration. System functionality has been verified by
in-vitro testing. Successful programming, measurement, and reporting
functions were shown. Drug delivery was verified with model drugs
using dissolution apparatus test equipment. The accuracy of the
amount of drug dispensed versus time was measured and found to be
better than 0.8% (average deviation over 0 - 95% volume dispensed).
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