New therapeutic uses for existing drugs
Drug repurposing can encompass any one of the following activities:
- Repositioning drug candidates that are currently in clinical development to new disease indications
- Targeting drugs that have been abandoned or failed to demonstrate efficacy for a particular indication during phase II or III trials to new disease indications
- Targeting marketed or off-patent drugs to new disease indications
- Reformulation of drugs including novel delivery systems
- Novel combination therapies
The drug Repurposing is based on knowledge of the biological and pathogenic mechanisms underlying the disease in which it is to be applied
Drug Repurposing: times and costs reduction
Through Drug Repurposing times and costs are significantly reduced since the pre-clinical costs are almost zero and the clinical phase 1, in which the safety and tolerability in the healthy volunteer is tested, is not necessary, because it is already available from the original registration documentation of the drug.
Clinical phase 2 studies, aimed at verifying safety (and, in part, effectiveness) are however facilitated, because the dosages of drug to be used and the timing of administration are well Known, while the clinical phase 3, which serves to confirm the safety and efficacy of the old drug in a larger patient population, must be carried out, but the design of the clinical study (and therefore its success) is greatly supported by the wide range of cases of patients to whom the drug has already been prescribed in its previous history.
Repurposing of existing drugs for new indications can offer a better risk-versus-reward trade-off as compared with other drug development strategies.
Repurposing: representative stories
Representative repurposing success stories include:
- Duloxetine: originally developed for depression and is now at the US FDA as a first-in-class therapy for stress urinary incontinence
- Dapoxetine: which was passed over as a follow-on to fluoxetine and is undergoing clinical trials as a first-in-class therapy for premature ejaculation
- Tiotepa: is an organophosphorus compound, analogue of N, N ‘, N’ ‘- triethylenephosphoramide, it was developed in the early 1950s
Its Massive use as an anti-tumor agent began only in the 1960s
Tiotepa was designated an orphan drug by the European Medicines Agency (EMA) on 29 January 2007 and by Food and Drug Administration (FDA) on 02 April 2007 for conditioning treatment prior to haematopoietic progenitor cell transplantation by Sponsor ADIENNE Pharma & Biotech
Repurposing is therefore an important way to revitalize drugs already in use or disused, directing them towards new diseases.