To control the sugar level in blood, diabetics
have to take injections regularly, up to several
times a day, which makes their life more difficult.
The lack of timely injection may result in a
fatal outcome. Chemists have developed polymeric
capsules to protect insulin from destructive
effect of digestive juices. The pills would
significantly simplify their life. However,
the fact that insulin gets quickly destroyed
when it appears in acid medium of the stomach
does not exclude, but significantly creates
problems for insulin in the pill form. Researchers
of the Chemical Faculty, Lomonosov Moscow State
University have found the way to protect insulin
from the destructive effects of the digestive
juices and to preserve the ability to perform
its function.
To introduce insulin in the organism, the Russian
chemists have used multi-layer polymeric capsules.
These polymeric capsules are stable and remain
intact in acid medium and they gradually excrete
insulin in a neutral medium. The two polymers
used are: positive protamin and negative dextransulphate.
They form layers in series one upon the other
according to the plus towards minus principle
and make a multi-layer covering around the insulin
filling, which makes up to 85% of the entire microparticle.
Insulin covered by protective capsule is stable
in acidic medium of pH from 1.7 to 5 units. When
pH increases to a level above 5units, insulin
gets released. Further pH increase of up to 8
units results in accelerated protein release rate.
Such behavior of particles occurs due to the fact
that at pH higher than 5.5 units of insulin acquires
negative charge and its bond with the negatively
charged polymer of the first layer - dextransulphate
- gets destroyed.
Such pH-dependence of protective polymeric capsules
provides fundamental capability to create insulin
in pills. In the stomach, where medium is extremely
acid, these capsules would protect the insulin
molecule and would not allow its destruction.
Having gone through the stomach and having reached
the small intestine and ileum, where pH reaches
6 to 8 units, capsules will start to excrete insulin
intensely. In thin intestines, insulin can penetrate
blood. Therefore, the capsule determines by itself
where insulin should be retained in closed form
and where it should be released.
The polymers used to create capsules belong to
natural biodegradable polymers. After utilization
they get easily destroyed by enzymes and removed
from the organism without causing any harm to
health.