Of all the problems that reduce quality of life for aging populations, eye diseases are certainly among the most intractable. While other illnesses have rapidly attracted a broad array of therapeutic strategies, the eyes their delicacy and complexity have stymied the development of broad advances, especially on the device side.
Now, researchers at the Georgia Institute of Technology (Georgia Tech; Atlanta) are pursuing a new method to deliver therapy to the eyes that could provide a platform for large advances in this sector. They are developing tiny needles micro-needles coated with drugs that could treat glaucoma, macular degeneration, diabetic retinopathy and other diseases leading to blindness, while avoiding the complications associated with current intraocular injections and systemic administration of drugs.
"The concept of microneedles existed a long time ago," Samirkumar Patel, a researcher at Georgia Tech, told Biomedical Business & Technology, noting that patents on these types of devices were filed in the 1970s. The patents described small needles "to create pathways into tissues to allow drugs to diffuse across a given tissue faster."
But Patel said these needle types targeted the penetration of skin.
Patel is part of a team that includes researchers from Emory University (Atlanta) who are working to exploit this concept for new therapeutic applications. "Our group at Georgia Tech designed and fabricated these microneedles in the 1990s," Patel said. "The reason they didn't exist until then is because the technology didn't exist to fabricate them at that [micro-sized] scale. We decided to branch out of transdermal delivery and started looking to deliver drugs into the eye, which is a completely new idea."
The solid metal microneedles, measuring 500 to 750 micro-millimeters in length, go only as deep as a half-millimeter into the tissue, not far enough to cause the damage — such as retinal detachment associated with traditional needles. And only local anesthetic is needed for their use.
They overcome the disadvantages of other system for delivering drugs to the eyes, according to Patel such as eye drops, that fail to reach the back of the eye; injections with standard hypodermic needles that are invasive, penetrating across eye tissues; and regular needles associated with a variety of vision complications. Invasive because the needle penetrates across eye tissues.
Patel said, "With eye drops, only 1% to 3% of the drug actually gets into the front portion of eye. It's a very low percentage for drug delivery efficiency. For older people who have serious vision issues, the drug needs to be delivered to the back of the eye and these injections are not one-time treatments. They are typically done multiple times over four to eight weeks. It's very invasive and repeated injections can cause complications."
Besides being less invasive, micro-needles are able to reduce the amount of drugs used, have fewer side effects and are likely to be less costly overall.
Whatever drug is delivered "can be designed to stay longer in the tissues and eventually diffuses into the retina," Patel said. "The microneedle has versatility to deliver drug to different parts of the eye. Now they just try to get it into the eye and hope it reaches the target. With the microneedle, you can selectively deliver to a region of the eye.
"So far, tests indicate the microneedles showed very little reaction from rabbits," he said. "In visual tests done within a matter of hours after delivery, you couldn't tell that anything happened."
Research on this method of ocular drug delivery is at a very early stage, the team so far working with eyes from cadavers and rabbits. Thus, Patel predicted that it could be at least five years until they enter clinical trial status.
Diabetes continuing rapid increase
For those looking to put their medical investment chips on the fastest-growing categories of disease, the best bet would appear to be diabetes. Nearly 24 million people in the U.S. have diabetes, an increase of more than 3 million over the past two years, according to new 2007 prevalence data estimates for 2007 released in late June by the Centers for Disease Control and Prevention (CDC; Atlanta). This means that nearly 8% of the U.S. population has diabetes.
In addition to the 24 million with diabetes, another 57 million people are estimated to have pre-diabetes, a condition that puts people at increased risk for diabetes. Among people with diabetes, those who do not know they have the disease decreased from 30% to 25% over a two-year period.
Dr. Ann Albright, director of the CDC's Division of Diabetes Translation, called the agency's estimates "good news and bad news." He said, "It is concerning to know that we have more people developing diabetes, and these data are a reminder of the importance of increasing awareness of this condition, especially among people who are at high risk.
"On the other hand, it is good to see that more people are aware that they have diabetes. That is an indication that our efforts to increase awareness are working, and more importantly, that more people are better prepared to manage this disease and its complications."
Diabetes currently is considered the seventh-leading cause of death in the U.S., while associated with a variety of other serious complications.
Among adults, diabetes increased in both men and women and in all age groups, but still disproportionately affects the elderly. Almost 25% of the population 60 years and older had diabetes in 2007. And, as in previous years, disparities exist among ethnic groups and minority populations including Native Americans, blacks and Hispanics.
After adjusting for population age differences between the groups, the rate of diagnosed diabetes was highest among Native Americans and Alaska Natives (16.5%). This was followed by blacks (11.8%) and Hispanics (10.4%), which includes rates for Puerto Ricans (12.6%), Mexican Americans (11.9%), and Cubans (8.2%). By comparison, the rate for Asian Americans was 7.5% with whites at 6.6%.
The data are an update of diabetes prevalence estimates last reported two years ago and now published in the 2007 National Diabetes Fact Sheet developed by CDC in collaboration with multiple agencies under the U.S. Department of Health and Human Services and other federal agencies.
CDC also is releasing estimates of diagnosed diabetes for all counties in the U.S. Derived from the agency's Behavioral Risk Factor Surveillance Survey (BRFSS) and census data, the estimates provide a clearer picture of areas within states that have higher diabetes rates. Nationally, the data indicate increased diabetes rates in areas of the Southeast and Appalachia that have traditionally been recognized as being at higher risk for many chronic diseases, including heart disease and stroke.
"These data are an important step in identifying the places in a state that have the greatest number of people affected by diabetes," said Albright. "If states know which communities or areas have more people with diabetes, they can use that information to target their efforts or tailor them to meet the needs of specific communities."
CDC, through its Division of Diabetes Translation, funds diabetes prevention and control programs in all 50 states, as well as the District of Columbia and eight U.S. territories and island jurisdictions. The National Diabetes Education Program, co-sponsored by CDC and the National Institutes of Health, provides diabetes education to improve the treatment and outcomes for people with diabetes, promote early diagnosis, and prevent or delay the onset of diabetes.
Pneumonia top cause of hospitalizations
Heart disease (including stroke) and cancer are the top two killers in the U.S. as well as worldwide but the No. 1 reason for hospitalization in the U.S., as the result of illness, is pneumonia.
According to figures from the Agency for Healthcare Research and Quality (AHRQ; Washington), more than 1.2 million Americans were hospitalized for this lung infection often deadly for older people in 2006 (though coming in second to childbirth, which produces the largest number of hospitalizations).
That figure is considerably deceptive however, since the agency breaks out a variety of diseases that generally are placed in the general category of heart disease: hardening of the arteries, heart attack, congestive heart failure, heart rhythm problems and chest pain, some of which may be heart-related.
The figures come from AHRQ's News and Numbers report, the agency noting that the 1.2 million pneumonia admissions is roughly equivalent to the population of Dallas.
The '06 hospital bill for treating the disease was $10 billion.
That, however, turned out not to be the largest dollar figure, since four other causes of hospitalization were in the $10 billion-or more category.
Following are AHRQ's figures for 2006 hospitalizations, by hospital costs and estimated admissions, for eight other common conditions:
• Hardening of the arteries: $17 billion 1,198,000 admitted.
• Heart attack: $12 billion 675,000.
• Congestive heart failure: $11 billion 1,099,000.
• Osteoarthritis: $10 billion 735,000.
• Heart rhythm problems: 749,000 $7 billion 749,000;
• Chest pain: $4 billion 857,000.
• Complications of labor and delivery (other than injuryto mother); $3 billion 767,000.
• Injuries to mother during birth: $2 billion 818,000.
AHRQ's News and Numbers is based on 2006 data in HCUPnet, a free online query system based on data from the Healthcare Cost and Utilization Project, providing access to health statistics on hospital inpatient and emergency department utilization.