Approximately
90% of all ophthalmic drug formulations are now applied as eye-drops. While
eye-drops are convenient and well accepted by patients, these are very
inefficient at delivering ophthalmic drugs. Only about 1-5 % of the drug
applied as drops penetrates the cornea and the remaining leaves the eyes
through the tear drainage. The drugs then enter the systemic circulation
through absorption in the nasolacrymal duct and in some cases cause
significant side effects. Furthermore, drug delivery by drops results in a
bolus delivery rather than a uniform dosage, and this may limit the efficacy
of ophthalmic drugs.
To
reduce drug loss and the systemic side effects, and improve drug delivery
profiles, Anuj
Chauhan and his research group have proposed nanoparticle-laden
disposable soft contact lenses as a new vehicle for ophthalmic drug
delivery. The essential idea is to encapsulate the ophthalmic drug
formulations in nanoparticles, and to disperse these drug-laden particles in
the lens material. They have successfully synthesized microemulsion and
liposome-laden p-HEMA lenses that are transparent and that can deliver drugs
for a period of about 4-5 days. The animal trials of these lenses are
expected to begin in a year and a product based on this technology is
expected to be in the market in about 8 years. Their work has received much
recent attention in the popular press including CNN Headline News, Frost &
Sullivan report, BBC, USA Today, Business Week, and was named in Reader's
Digest Medical Breakthroughs 2004. This work is supported by NSF and by one
of the largest contact lens companies in the United States.
