DRUG RE PURPOSING - MAKING MARVELLOUS OUT OF THE EXISTING

Thalidomide was once a well-known drug used for morning sickness in pregnant women,  then withdrawn in 1961 for its teratogenic effects which led to limb defects in more than 80% of children exposed in utero. And again, it regained its position in the market after a couple of years with brand new indications, as a potential remedy for the treatment of leprosy and multiple myeloma - a clear cut evidence of how drug repurposing can breathe in new life to a failed drug.

According to reports, the number of FDA approvals has been declining since 1995 with a success rate of merely 9.6% for the drug development programs from 2006-2015. In this scenario, drug repurposing or reprofiling presents as an efficient, economic and riskless innovation that can bring out promising results. Kudos to the efforts of those brilliant brains for working tirelessly on this drug development strategy, that modifies old drugs for new uses!

The basic idea behind drug repurposing is the fact that common molecular pathways contribute to many different diseases.It is indeed a consequence of the principle of polypharamacology and hence  represents a shift from the single to multiple target paradigm in drug discovery.

 While the conventional de-novo drug discovery process takes about 10-15 years for the translation of a promising molecule to an approved drug, this approach takes only about 1-2 years to identify new drug targets and an average of 8 more years to develop a repositioned drug. It is actually a boon to those with rare and neglected critical illnesses, for whom the big pharma are not willing to work due to low return on investment. Lack of activation barriers, decreased number of clinical trials, which in turn cut down time,cost and labour are the added advantages of this approach. However, lack of expertise in the legal area of drug repositioning, coupled with the complexity of pathways and mechanism of diseases makes this a cumbersome process  in the eyes of atleast a few.

Drug repurposing was sometimes just serendipitous -like those of sildenafil, originally meant for hypertension now being used to treat eretile dyfunction! But the need of the hour is the development of a deliberate systematic approach with a blend of experimental and computational aids to bring out life changing transformations.

DRUG REPURPOSING FOR COVID-A GLOBAL NEED

From the late fall of 2019, we have been witnessing the most devastating pandemic ever known. As of now, the best justified drugs for repurposing to treat covid are the host factor targeted drugs- hydroxychloroquine, azithromycin, camostat, nafamostat and the viral Rdrp targeted drugs-remdesivir and favipiravir. Additionally, phenotypic screening methods based on viral entry and replication are on development to survey more drug candidates.It has in fact become a global emergency that calls for researchers, ethics boards and regulatory bodies to come and work together on this concept to cobat the COVID!! 

Miss Rimisha Thomas IV Pharm.D