Biomedical Engineering Reference
In-Depth Information
Drug Delivery
One application of nanotechnology in medicine currently being developed
involves employing nanoparticles to deliver drugs, heat, light, or other substances
to specific types of cells (such as cancer cells). Particles are engineered so that they
are attracted to diseased cells, which allows direct treatment of those cells. This
technique reduces damage to healthy cells in the body and allows for earlier
detection of disease. The basic point to use drug delivery is based upon three facts:
(a) efficient encapsulation of the drugs, (b) successful delivery of the said drugs to
the targeted region of the body, and (c) successful release of that drug there.
Nanomedical approaches to drug delivery enter on developing nanoscale
particles or molecules to improve drug bioavailability. Bioavailability refers to the
presence of drug molecules where they are needed in the body and where they will
do the most good [
1
,
2
]. Drug delivery focuses on maximizing bioavailability both
at specific places in the body and over a period of time. This can potentially be
achieved by molecular targeting by nanoengineered devices. It is all about tar-
geting the molecules and delivering drugs with cell precision. More than $65
billion are wasted each year due to poor bioavailability. In vivo imaging is another
area where tools and devices are being developed. Using nanoparticle contrast
agents, images such as ultrasound and MRI have a favorable distribution and
improved contrast. The new methods of nano-engineered materials that are being
developed might be effective in treating illnesses and diseases such as cancer.
What nano-scientists will be able to achieve in the future is beyond current
imagination. This might be accomplished by self- assembled biocompatible nano-
devices
that
will
detect,
evaluate,
treat,
and
report
to
the
clinical
doctor
automatically.
Drug delivery systems, lipid- or polymer-based nanoparticles can be designed
to improve the pharmacological and therapeutic properties of drugs [
3
,
4
]. The
strength of drug delivery systems is their ability to alter the pharmacokinetics and
biodistribution of the drug. When designed to avoid the body's defence mecha-
nisms, nanoparticles have beneficial properties that can be used to improve drug
delivery. Where larger particles would have been cleared from the body, cells take
up these nanoparticles because of their size. Complex drug delivery mechanisms
are being developed, including the ability to get drugs through cell membranes and
into cell cytoplasm. Efficiency is important because many diseases depend upon
processes within the cell and can only be impeded by drugs that make their way
into the cell. Triggered response is one way for drug molecules to be used more
efficiently. Drugs are placed in the body and only activate on encountering a
particular signal. For example, a drug with poor solubility will be replaced by a
drug delivery system where both hydrophilic and hydrophobic environments exist,
improving the solubility. Also, a drug may cause tissue damage, but with drug
delivery, regulated drug release can eliminate the problem. If a drug is cleared too
quickly from the body, this could force a patient to use high doses, but with drug
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