Drug repurposing (also known as drug repositioning or DR) is a strategy for discovering new uses for FDA approved and investigational drugs. It is therefore, an effective process for identifying new therapeutic uses for old/existing and available drugs. Drug Repurposing offers several advantages over developing a novel drug for a given sign. There are examples from our past are which provide ample amount of evidence in favor of drug repurposing or drug repositioning.
Better the drugs you know than the drugs you do not know
It is a promising, fast, and cost effective method that has allowed researchers to forfeit traditional methodologies in drug discovery and development. Traditional methods of finding new drugs take a long time, and there are many regulatory barriers. It can take 9-10 years for a new medicine to come to the market through the normal method.
Some examples of drug repurposing
Drug repurposing is not a new activity. Some examples include
Aspirin is a Non-steroidal anti-inflammatory drug (NSAID) an antithrombotic medicine used for pain, fever and / or inflammation since 1899 all over the world.
Thalidomide was first introduced as an oral medication used by pregnant women to relieve morning sickness, anxiety, sleeping disorder. Now it is used as a first line treatment for multiples of cancer types including Multiple myeloma and various skin conditions such as leprosy and it is consumed orally.
Sildenafil a drug introduced initially as a reliever of heart pain but later new uses were discovered for it as a medication for erectile dysfunction which is now prescribed over 2 million times in the USA and is cited as a prime example for Drug Repositioning / Drug Repurposing.
A recent example for of drug repurposing is COVID-19 medication which utilized anti-parasitic drugs such as chloroquine and hydroxychloroquine which were repurposed for the treatment of the disease.
Although drug repurposing is an effective way of treatment it does come with limitations such as a high cost of clinical trials, lack of patent protection and commercialization, FDA offers only a period of three years exclusively for a new use of previously used drug for a new indication, which is a very short period of time to regain the invested money and in case a loss for the pharmaceutical industry.
The pharmaceutical industry has seen a lot of changes over the past few decades, Covid-19 vaccine and the case of Viagra before that has produced a whole new meaning of Drug Repurposing. It is beneficial at most times but this does not mean that they do not have any short comings.
You can read all about drug repurposing in the new book Drug Repurposing against SARS-CoV-2 (edited by Tabish Qidwai)to learn more about it.
Book link: Drug Repurposing Against SARS-CoV-2 (benthambooks.com)
Bentham Science 