Introduction

Drug repurposing, also known as drug repositioning or drug reprofiling, stands as a promising strategy for discovering new therapeutic uses for existing drugs. This approach accelerates drug development, saving valuable time, resources, and costs compared to the traditional route of creating new drugs. The realm of drug repurposing becomes even more intriguing with the integration of Computer-Aided Drug Design (CADD), a powerful tool that leverages computational methods to aid in the discovery and optimization of drug candidates.

The Role of CADD in Drug Repurposing

The complexity of drug repurposing lies in understanding the molecular mechanisms of diseases and drugs, as well as identifying and validating novel drug-target interactions. CADD, with its two main approaches—structure-based and ligand-based—plays a crucial role in overcoming these challenges.

Structure-Based CADD

In structure-based CADD, knowledge about the three-dimensional structure of the target protein or enzyme is utilized. This approach aids in the identification or design of ligands that can interact with the active or allosteric sites of the target. This method is instrumental in virtual screening and molecular dynamics simulations, evaluating the binding affinity and stability of drug-target complexes.

Ligand-Based CADD

Ligand-based CADD relies on the chemical structure and properties of known ligands. It helps in finding or designing compounds that can modulate the same or different targets. Techniques such as similarity searches, diversity searches, pharmacophore modeling, and Quantitative Structure-Activity Relationship (QSAR) analysis fall under this category.

Successful Applications of CADD in Drug Repurposing

Several drugs have been successfully repurposed for various diseases through the application of CADD. Some notable examples include:

Remdesivir: Originally developed for Ebola, it was repurposed for COVID-19 by inhibiting the RNA-dependent RNA polymerase of SARS-CoV-2 through structure-based CADD.

Hydroxychloroquine: Initially an antimalarial drug, its repurposing for COVID-19 was explored through ligand-based CADD, revealing interference with the endosomal entry and replication of SARS-CoV-2.

Vorinostat: Approved for cutaneous T-cell lymphoma, it was repurposed for glioblastoma by inducing apoptosis and autophagy through structure-based CADD.

Metformin: Widely used for type 2 diabetes, it was repurposed for cancer treatment by modulating multiple targets and pathways through ligand-based CADD.

Challenges and Considerations

While CADD demonstrates immense potential, it comes with limitations such as the accuracy of computational models, data availability, and ethical considerations. It is crucial to combine CADD with experimental and clinical validation, as well as other sources of information to ensure a comprehensive understanding of diseases and drugs.

Conclusion

In conclusion, CADD stands as a powerful tool for drug repurposing, providing insights and hypotheses that guide the discovery of new therapeutic indications for existing drugs. As computational and technological capabilities continue to evolve, CADD will play a vital role in drug repurposing, offering innovative solutions and contributing to the advancement of personalized medicine.

References

(1) Computer-Aided Drug Design (CADD): Types, Uses, Examples, Softwares. https://microbenotes.com/computer-aided-drug-design-cadd/.

(2) Drug Repositioning Using Computer-aided Drug Design (CADD). https://www.eurekaselect.com/article/133863.

(3) Tool and Techniques on Computer-Aided Drug Design for Targeted Cancer Therapy. – Springer. https://link.springer.com/chapter/10.1007/978-981-19-9786-0_23.

(4) Application, principle, advantages and new advanced technique used in CADD. https://ijirt.org/master/publishedpaper/IJIRT161640_PAPER.pdf