CBE Seminar - Anuj Chauhan

Anuj Chauhan, Department Head and Professor, Chemical and Biological Engineering, Colorado School of Mines

Ophthalmic Drug Delivery By Contact Lenses

Abstract

Ophthalmic drugs are almost always delivered via eye drops in spite of many deficiencies including low bioavailability and poor compliance, particularly in patients requiring multiple eye drops daily.  Only about 1-5% of the drug in eye drops diffuses into the cornea and the remaining 95-99% enters systemic circulation through multiple pathways including tear drainage and conjunctival absorption.  Contact lenses are placed directly on the cornea with a thin 5-10 micron thick post-lens tear film (POLTF) layer in between, which makes contacts a natural choice for delivering drugs to the cornea. The drug released by the contact towards the cornea surface is trapped in the POLTF for extended duration of at least 30 min allowing transport of a large portion into the cornea. Our model predictions backed by in vivo animal data show that the bioavailability increases to about 50% with contact lenses. This realization has encouraged considerable research towards delivering ocular drugs by contact lenses. Commercial contacts are, however, not ideal for drug delivery due to the short release durations which may necessitate wearing multiple lenses each day, reducing the viability of this approach. In this talk, I will cover our efforts on designing contacts that retain all critical properties while increasing the release durations to a few hours or a few days. We have developed nanoparticle loaded lenses to increase drug release durations either by attaching drugs to particles with cleavable bonds or by designing particles with high affinity for the drugs.  Examples include microemulsions, liposomes, vesicles and polymeric particles.  These approaches are effective but suffer from some limitations including destabilization during autoclaving and potential release of drug during packaging.  Recently, we have developed an alternative approach based on incorporating vitamin E into silicone hydrogel contact lenses to create diffusion barriers.  This approach significantly increases release duration about 20 to 200-fold depending on the vitamin E loading, while retaining all key properties.  Beagle dog studies with contact lenses containing vitamin E nanobarriers to attenuate drug transport show superior reduction in intraocular pressure with lower drug payloads, and a considerably longer duration of efficacy than wear duration due to creation of drug depots.  Other studies in cornea injury model also show promising efficacy.  Preliminary human studies show safety and efficacy at glaucoma therapy including extended duration of pressure reduction beyond the wear duration. I will also touch upon some efforts to develop highly lubricious lenses to improve lens comfort and delivery of drugs to the back of the eye using contact lenses.  Time permitting, I will show some of the recent work on gold nanoparticle loaded contact lenses that can be useful in protecting eyes from laser injury as well as treating dry eyes.

Bio

Anuj Chauhan joined the Colorado School of Mines as the Department Head in August 2019.  Prior to that he was a faculty in the Chemical Engineering department at the University of Florida from 2001-2018.  Born and raised in Jaipur, India, Anuj obtained his undergraduate degree in Chemical Engineering from the Indian Institute of Technology in Delhi, after which he moved to the United States in 1993 to pursue doctoral studies at the Levich Institute for Hydrodynamics at the City College of New York.  He pursued doctoral research on hydrodynamic stability of liquid compound jets under the guidance of Charles Maldarelli and David Rumschitzki.  After finishing PhD in 1998, Anuj went to the University of California at Berkeley for post-doctoral research with Clay Radke on the movement and deformation of a contact lenses in eyes due to the blink-interblink cycle.    Anuj joined the University of Florida as an Assistant Professor in the Chemical Engineering department 2001.  He achieved the rank of professor in Florida's Department of Chemical Engineering in 2011 and served as associate department head from 2013 to 2018.  He had the honor of serving as the first Dinesh O. Shah Distinguished Faculty Fellow of Chemical Engineering.

Anuj’s research interests center around transport and interfacial phenomena in biological systems particularly focusing on drug delivery.  Fascinated by the eyes, he has been pursuing many problems in ophthalmology including developing novel contact lenses for improved comfort and also using contacts for delivering drugs to treat many ocular diseases including glaucoma, Cystinosis, dry eyes, infections, allergies, macular degeneration and diabetic retinopathy.   Other problems of interest include modeling ocular physiology, developing preservative free multidose eye-drops, and understanding tear film drainage and breakage. His work on ophthalmic drug delivery via contact lenses was named one of the Medical Breakthroughs of the Year by Readers Digest in 2004 and received media coverage in many countries.  His research goals include translating his research to commercialization, hoping to make a significant positive impact on the patients’ lives.  A start-up company is currently conducting clinical studies with technology developed in Anuj’s lab for managing glaucoma using contact lenses and another start up is focusing on developing multidose preservative free eyedrops.  He has published 140 papers and submitted 30 patent applications.  Many of these patents are licensed by large companies and startups.