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Advances likely in the delivery of currently available drugs
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 Richard L. Lindstrom |
The development of sustained-release drug delivery methods and devices is a hot area for research today. Part of this is related to need and part to the fact that it is becoming increasingly more difficult and expensive to develop a new patented proprietary drug with a unique therapeutic profile.
Generic drugs now represent nearly 70% of what is dispensed in the U.S. It is interesting that, while less profitable for the manufacturer, generic drugs generate the best profit margin for the dispensing pharmacist. Generics are also strongly preferred by third-party payers or patients personally paying for their medications for the obvious reason that they are much less expensive. Facing the daunting barrier of a 10- to 12-year approval cycle and an investment of nearly $1 billion to develop a new proprietary drug, many established and start-up entrepreneurial companies, large and small, are pursing methods to deliver current drugs more effectively.
There is clearly a need for these sustained delivery models. Many studies and all our collective clinical experience confirm that perfect compliance with a doctor-recommended therapeutic drug regimen is quite rare. As many as 30% of patients who are instructed to take a single glaucoma drop each day fail to do so reliably, and as the treatment regimen is increased to two or three medications, compliance falls to less than 50%. In addition, for one reason or another, many patients who require drug therapy are simply unable to administer it to themselves. Some have infirmities that interfere with proper use of drops, and some have issues with poor memory. One creative solution is to develop a sustained delivery device or methodology that reduces dependence on patient compliance.
We are all very excited to see more of these options become available. Disease states that seem particularly well-suited for this approach include glaucoma, chronic uveitis, chronic macular edema associated with diabetes mellitus, vein occlusion or the like, and exudative age-related macular degeneration. Prophylaxis against postsurgical infection and the treatment of postsurgical inflammation with a single application of a sustained-release drug delivery device applied or implanted at the time of surgery would be a very attractive option.
Arguably, we have been using this approach for decades through the use of depot steroids injected subconjunctivally, but much more elegant and less invasive approaches are in development. Especially interesting to me are the drug-implanted punctal plugs, the idea of impregnating IOLs and other implantable devices with antibiotics and anti-inflammatories, the concept of a drug-releasing wound sealant and the many approaches being developed for long-term therapy of chronic posterior segment pathology. It will benefit both our patients and us to have these sustained-release devices available. So, while we are likely to see fewer new pharmaceuticals approved over the next decade, we can look forward to significant advances in our ability to apply our currently approved drugs in a safer and more effective way.