You read correctly. Two separate studies have shown that the antidepressant Prozac and the gas that comes out of car and truck exhausts, carbon monoxide, can be used to preserve vision.
Starting with Prozac, also known as fluoxetine, it may be effective against dry or atrophic age-related macular degeneration (AMD). Bradley D. Gelfand, PhD at the University of Virginia thinks that Prozac works against dry AMD by binding with an inflammasome NLRP3-ASC, an agent of the immune system. This inflammasome triggers the breakdown of the pigmented layer of the retina.
Researchers in his lab tested Prozac and other depression drugs in laboratory mice to see what effect they would have on dry AMD. Only Prozac slowed the progression of the dry AMD, the others did not. They also delved into insurance databases to see what affect Prozac use had on the development of dry AMD. Those who took the drug had substantially slower rates of developing dry AMD.
What makes this research so promising is that it deals with a drug that already has approval from the Food and Drug Administration (FDA) and is currently being used by millions of people. The usual approach to drug development takes over 10 years and costs over $2 billion dollars to develop. Utilizing existing FDA approved drugs by using both data mining and lab research can hasten and reduce the cost of drug development. The next step in this research is to conduct a clinical trial on patients with dry AMD.
Next comes research with carbon monoxide. Yes, carbon monoxide in large amounts is poisonous. This research deals with using carbon monoxide in small doses to preserve vision in those with Type 1 and Type 2 Diabetes.
Scientists at the Medical College of Georgia have found that an oral drug, HBI-002, developed by Hillhurst Biopharmaceuticals, can reduce oxidative stress and inflammation in the retina, which are major contributors to diabetic retinopathy.
Our cells are actively producing small amounts of carbon monoxide to protect themselves from inflammation and oxidative stress. One enzyme in particular, heme oxygenase 1 is tasked with reducing inflammation and oxidative stress. One way it does that is by releasing small amounts of carbon monoxide that is 1,000 times lower than what is found in automobile exhaust. This small and steady production of carbon monoxide means that it doesn’t accumulate in our body.
In diseases like diabetes, the body’s mechanisms fail and ways to reestablish those mechanisms need to be developed. That’s where HBI-002 comes in. Scientists are looking at the impact of the drug both when the retina is not getting enough oxygen because of oxidative stress followed by inflammation, as well as natural disease progression.
Cells in the retina generate a lot of oxidative stress, so there has to be a way to prevent damage to the retina. HBI-002 turns carbon monoxide into a gas in the intestines, where it binds to hemoglobin, the oxygen carrying part of blood. From there, it goes to the eye. Once in the retina, the small dose of carbon monoxide finds the heme oxygen’s enzyme and starts the process that leads to anti-oxidant and anti-inflammatory actions.
The transformation of HBI-002 from liquid to gas allows for targeted dosing and if approved for use in humans, it will help ensure accurate dosing. It also leaves no byproduct behind. A pill form of this drug left behind metal complexes that had to be eliminated by the kidneys, which are usually compromised in persons with diabetes.
While Prozac and carbon monoxide aren’t thought of as a means to preserve vision, these two research projects show that developing something new isn’t always necessary. Treatments can be developed from what is currently available.