Biomedical Engineering Reference
In-Depth Information
6 Conclusions
Effective treatment of ocular diseases is a challenging task because
of the complex nature of diseases and presence of ocular barriers
which hinder delivery of therapeutic agents in required levels. Age-
related chronic ophthalmic disorders are expected to rise dramati-
cally in the next two decades. Hence, there is an unmet need to
develop new ophthalmic formulations that meet the multi-
medication needs of the elderly patients. An ideal ophthalmic
formulation would be easy to manufacture, permit noninvasive
self-administration, and attain and sustain effective drug concen-
trations at the target site for desired time periods. It must also
produce negligible systemic exposure and afford good patient well-
being, acceptance, and compliance. Over the last two decades there
has been a significant growth in the development of formulations
which would efficiently incorporate agents and sustain release fol-
lowing topical ocular administration. But none of these formula-
tions have advanced into clinic. Eye drops still account for 90 % of
all ophthalmic formulations and are considered ideal for treating
anterior segment disorders. However, these formulations may not
be able to deliver drugs to the back of the eye. An ideal therapy
should maintain effective levels for a longer duration following a
single application. Drug delivery by intravitreal routes cannot be
particularly considered safe, effective, and patient friendly. Drug
delivery by periocular route can potentially overcome many of
these limitations and can provide sustained drug levels in ocular
pathologies affecting both segments. Nevertheless, the selection of
an administration route is also dependent on the severity of the
disease and the target ocular tissue. A clear understanding of
the complexities associated with normal and diseased conditions,
physiological barriers, and pharmacokinetics would significantly
improve drug development in this field. Currently there is no
product approved for treating back-of-the-eye diseases via nonin-
vasive topical drug administration. Much emphasis should be given
to noninvasive sustained drug delivery for both front- and back-of-
the-eye disorders. Development of noninvasive delivery techniques
will revolutionize retinal drug delivery. Advances in noninvasive
drug delivery techniques will remain in the forefront of new oph-
thalmic formulations.
Acknowledgements
This work was supported by NIH grants R01EY09171 and
R01EY010659.
