Medical Design Briefs - September 2023 - 21

A more targeted approach would be
the controlled degradation of the hydrogel
to release the medicine.2 Ultrasound
has been proven effective at breaking
down a hydrogel and allowing the release
of drugs. This method allows for
noninvasive, targeted delivery of a drug
to a specific site in the body.
Oral Delivery of Delicate Medications
Hydrogels can unlock the ability to administer
drugs that would not normally
survive the process orally. Certain drugs
need to pass through the stomach to be
effective but are unable to withstand the
acidic pH conditions of the stomach. In
one such case, it was found that encapsulating
Amifostine (a chemotherapy
drug) in a hydrogel allowed it to safely
pass through the stomach to be delivered
into the intestines.3
Allowing oral administration of certain
drugs can improve a patient's ability
to administer treatments at home and
make it safer and easier to undergo certain
treatments. Encapsulating drugs in
this way can also improve the shelf life of
certain medications, as the hydrogel provides
additional stability.
Stimuli-Responsive Hydrogels
While gel degradation can be used to release
medication, sometimes developers
want even more control of a drug's release.
For this, stimuli-responsive hydrogels provide
a solution. These are gels that change
their absorption capacity based on the environment
that they are in. Hydrogels can
be formulated to be light-sensitive, temperature-sensitive,
electrically sensitive, etc.
The idea of stimuli-responsive hydrogels
is to use a multistep process. First,
the gel is swollen with a medicated solution.
The swollen gel is then transferred
to the target area within the body. Then
the conditions are changed. This can be
any number of factors depending on the
area that is getting targeted. This change
in conditions reduces the gel's swelling
capacity, and the medication is released
to the targeted area.
The advantage of stimuli-responsive
hydrogels is the ultimate control of
where the active ingredient is dosed and
how quickly the dose is administered.
Conditions can be changed suddenly to
release a drug all at once or slowly to enable
fine control of the release rate.
These hydrogels also allow for fine
control of where a drug is released. HyMedical
Design Briefs, September 2023
Hydrogels can unlock the ability to administer drugs that would not normally survive the process orally. (Credit:
edwardolive/iStock)
drogels can be designed to do this if developers
want to efficiently target a certain
organ of the body or even certain
types of cells.
Managing Diabetes
For diabetes, pH-responsive hydrogels
with the enzymes glucose oxidase and
catalase incorporated into their network
will swell in the presence of glucose. Insulin
can be encapsulated within these
hydrogels, with the gel acting as a barrier
between the insulin and the body.4
When higher glucose concentrations
are present in a user's blood, the hydrogel
will swell, allowing the insulin to migrate
out of the device. As the insulin
takes effect, glucose levels will drop, and
the hydrogel will shrink, cutting off the
supply of insulin. Effectively, the system
is a closed loop, self-regulating the blood
glucose to within optimal levels.
A hydrogel loaded with drugs can be injected into a cancer site, targeting the release of the drugs toward cancerous
cells, leaving healthy ones unharmed. (Credit: Henadzi Pechan/iStock)
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Medical Design Briefs - September 2023

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