To date, the US Food and Drug Association (FDA) has approved over 19,000 prescription drugs for marketing. That’s an awful lot of drugs that are circulating around in our health care facilities. 

And yet, the number is projected to grow. This is because intensive research into disease areas of interest, such as cancer and immunological diseases, continues to attract investment, allowing scientists to conduct trials that are designed with the very best methodology. 

We have never had as many medications for as many illnesses as we do today. It is truly remarkable that we now have access to thousands of drugs and know a great deal about their mechanism of action, pharmacology, pharmacokinetics, and side effects. Now, everyone can access journals, studies, and papers on available drugs for existing maladies at a click of a button. 

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It is worth spending a few moments reflecting on how drugs are usually created. Some of the most important drugs in medical history come about through unusual means, such as penicillin. Modern pharmaceutical companies develop drugs for specific diseases, often with the intent of filling in an existing gap, and they conduct clinical studies phase by phase until the drug (hopefully) receives final approval from the FDA for use in a subset of the patient population. 

Pharmaceutical companies are businesses, not charities, thus we cannot overlook the element of profit-making in their endeavors. However, without the money, enthusiasm, and innovation from these stakeholders, medicine would not have been able to progress as quickly. 

What about the diseases, like Alagille syndrome (ALGS), that still do not have enough high-quality drugs that can considerably alter disease progression and improve outcomes? Pharmaceutical companies may have once decided to test out a few drugs, to no avail. Hence, patients are left with having to make do with whatever is left in the therapeutic arsenal. 

The Needs of the Rare Disease Community  

“Currently, there are about 7000 identified rare diseases, together affecting 10% of the population,” Roessler and et al write in Trends in Pharmacological Sciences. “However, fewer than 6% of all rare diseases have an approved treatment option, highlighting their tremendous unmet needs in drug development.”

Let that sink in—just 6% of rare diseases even have an approved treatment option. 

Collectively, rare diseases affect around 300 million people around the world. In addition, some rare diseases are rarer than others: Hutchinson-Gilford progeria syndrome, a disease that causes premature aging, has an incidence of 1 in 8 million live births; Huntington’s disease, on the other hand, affects around 3 to 7 per 100,000 people of European ancestry. 

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Nonetheless, rare diseases tend to share a few similarities. First, many rare diseases are multisystemic, affecting various organs in the body. This is especially true if the disease, through one mechanism or another, results in end organ failure. 

Second, they tend to be misdiagnosed initially. This could be due to a variety of factors: an inexperienced physician, vague clinical presentation (such as in the case of Lyme disease), or signs and symptoms that typically suggest a more common disease that protocol dictates should be ruled out before rarer ones are suspected. This means that patients with rare diseases often do not get diagnosed and treated promptly, if at all. 

The worry and anxiety that this generates among patients add a psychiatric element to their suffering. So what strategies do we have to ensure that we get the right drug to the right patient in a way that is timely, efficient, and innovative? 

Drug Repurposing as Strategy

“Drug repurposing (also known as drug repositioning or drug reprofiling) is the process of redeveloping a compound for use in a different disease,” Roessler and colleagues write. “It is now becoming an increasingly important strategy for researchers in industry and academia.” 

The fundamental belief driving drug repurposing is that the current drugs that we do have may yet possess therapeutic aspects we aren’t fully aware of unless they are re-explored from an entirely different angle. 

And this strategy has shown some success. Studies demonstrate that repurposed drugs can reach the market in only a few years. The success rate of drug repurposing ranges between 30% and 75%. 

Fortuitously, we do have a means of sorting through large quantities of data and finding patterns that may bring about renewed perspectives on the data studied: artificial intelligence (AI). Some scientists are convinced that AI will play a central role in revolutionizing drug repurposing. 

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Because AI can process vast amounts of data within a short period of time, it is best positioned to suggest drugs for repurposing that have the highest chance for success. AI absorbs data and “learns,” meaning that no input is wasted. AI is this century’s wild wild West in terms of the incredible frontiers it opens up, for drug repurposing and beyond. 

“To date, AI’s potential ability to identify new candidate therapies that can be made available for clinical trials rapidly and, if approved, merged into health care is unparalleled, making AI a centrepiece of advanced technologies,” Zhou and colleagues write in the Lancet Digital Health. ”Because of this, AI is a promising method for accelerating drug repurposing for human diseases, especially emerging diseases, such as COVID-19.”


Roessler HI, Knoers NVAM, van Haelst MM, van Haaften G. Drug repurposing for rare diseasesTrends Pharmacol Sci. 2021;42(4):255-267. doi:10.1016/

Zhou Y, Wang F, Tang J, Nussinov R, Cheng F. Artificial intelligence in COVID-19 drug repurposingLancet Digit Health. 2020;2(12):e667-e676. doi:10.1016/S2589-7500(20)30192-8

US Food and Drug Association. Regulated products and facilities. August 2018. Accessed December 8, 2022.