New Therapeutic Applications of Old Drugs

**47**

**Chapter 3**

**Abstract**

dermatoses.

hyperpigmentation

**1. Introduction**

current strategies of drug discovery.

and errors were the main players in most of these cases.

billion dollars in the process.

Drug Repurposing in

and Omics Approach

*Farid A. Badria and Abdullah A. Elgazar*

Dermatology: Molecular Biology

The withdrawal of several blockbuster drugs due to severe adverse effects and the failure of several developed drugs in clinical trials raised questions about the efficacy of current approaches of drug discovery. Moreover, the limitation of resources and the long and costive process of drug discovery made a lot of pharmaceutical companies to employ drug repurposing strategies to get new insights about activities that were not considered during their initial discovery. The development of therapeutics for treatment of dermatological condition is not considered as priority although it affects the lifestyle of thousands of people around the world. Serendipity and observations have contributed significantly in this field but immerse efforts have been exerted to find systematic methods to identify new indications for drugs, especially with the unprecedented progress in molecular biology and omics. So, in this chapter, we will emphasize on different approaches used for drug repositioning and how it was applied to find new therapeutics for different

**Keywords:** drug repositioning, alopecia, psoriasis, acne, hirsutism,

In the early years of this century, it was expected that revolutionary development in industry and technology will allow an unprecedented opportunities for drug discovery and development; however, the disappointing rate of drug approval in the last 20 years shed the light on the urgent need to reassess the efficiency of

Despite the large amount of investment that has been put in drug development, several drug candidates fail to pass due to pharmacokinetic issues or severe side effects that mainly are not demonstrated until clinical phases, which lead to extreme economic loss to pharmaceutical companies that might spend more than

These facts were not overlooked by pharmaceutical industries or academia; so, they started to apply a new strategy that embraces new application of approved drugs rather than starting from scratch, which is known as drug repositioning. While the term was first coined in 2004, the approach has already led to the discovery of several therapeutic agents in the last century; however, serendipity, trials,
