Author detail:

Rimsha Arooj¹, Sehar Shahzadi²

¹Department of Chemistry, University Of Agriculture Faisalabad, Sub-Campus Toba Tek Singh

²Department of Chemistry, Government College University Faisalabad

1. Introduction

Developing a new drug from inception to market launch is an intricate process spanning over 12-15 years and requiring an investment exceeding $1 billion. The journey begins with the identification of a potential target, which can originate from various sources such as academic research, clinical observations, or the commercial sector. However, it often takes years to accumulate sufficient evidence to select a target for further drug discovery efforts.

2. Phases of Drug Development

• Identification of drug targets
• Validation of drug targets
• Identification of lead compounds
• Optimization of lead compounds
• Characterization of the product and formulation development
• Preclinical research
• Submission of Investigational New Drug (IND) application
• Submission of New Drug Application (NDA)
• Conducting clinical trials
• Regulatory approval

3.1  Target identification

Drugs often fail during clinical trials for two primary reasons: they either lack efficacy or pose safety concerns. Therefore, one of the pivotal steps in developing a new drug is the identification and validation of a suitable target. Targets encompass various biological entities such as proteins, genes, and RNA. An ideal target must exhibit efficacy, safety, clinical and commercial viability, and must be “drug able” – meaning it can be accessed and influenced by the drug molecule, whether small or large, to elicit a measurable biological response in vitro and in vivo (Tamimi & Ellis, 2009).

3.2     Target Validation

Experimental validation of drug targets is crucial to ascertain their proposed mode of action and directly correlates with the likelihood of clinical efficacy. Human cell or tissue experiments are particularly significant in this regard. Functional studies may involve genetic knockdown or knockout techniques, along with the utilization of target-specific tools such as small molecule compounds or antibodies. In vitro, cell-based mechanistic studies help uncover the regulatory characteristics of targets and the associated pathways.

3.3       Determining the Lead

Identifying the lead compound is a crucial phase in drug discovery, involving thorough screening of compound libraries to find molecules with desired biological activity against a target. These lead compounds undergo optimization to improve potency, selectivity, and pharmacokinetic properties, setting the stage for further development (Berdigaliyev & Aljofan, 2020).

3.4      Lead candidate optimization

In the progression of drug discovery, molecules initially designated as “Leads” undergo a crucial stage known as optimization. This phase is considered vital for enhancing the efficacy, potency, and pharmacological properties of the leads. Through strategic chemical modifications guided by structure-activity analysis, efforts are directed toward developing superior analogs. Additionally, if the target structure is identified, structure-based design techniques may be employed to introduce these modifications.

3.5       Product development, formulation, and characterization

             During product development, scientists focus on optimizing drug formulations to ensure stability, efficacy, and patient acceptability. Formulation involves selecting appropriate excipients, determining dosage forms, and optimizing manufacturing processes to achieve desired drug delivery profiles. Characterization involves assessing the physical, chemical, and biological properties of the formulated product, including its stability, solubility, bioavailability, and release kinetics. Through meticulous experimentation and analysis, researchers strive to develop robust formulations that meet regulatory requirements and address the needs of patients, paving the way for successful commercialization and clinical use (Deore, Dhumane, Wagh, & Sonawane, 2019).

3.6       Preclinical research

Preclinical studies, typically conducted in animals, serve multiple purposes in the drug development process. Initially, these studies evaluate the compound’s toxicity in animals without the target disease, followed by assessments in disease-specific animal models to gauge potential therapeutic effects. The primary goal is to secure FDA approval for an Investigational New Drug (IND) application, paving the way for subsequent human trials.
3.7    Submission of an Investigational New Drug (IND)

Its application marks a critical milestone in the drug development process. It involves the compilation and submission of comprehensive documentation to regulatory authorities, such as the Food and Drug Administration (FDA) in the United States, seeking authorization to initiate clinical trials of a new drug candidate in humans. Additionally, the application outlines plans for monitoring and reporting adverse events during clinical trials and includes the qualifications of investigators and clinical trial sites. Upon submission, regulatory agencies review the IND application to ensure that the proposed clinical trials are safe, ethical, and scientifically valid, ultimately determining whether to grant permission for human testing.

3.8    Submission of a New Drug Application (NDA)

It signifies a crucial phase in the drug development process, representing the culmination of extensive research and clinical testing.  Regulatory authorities meticulously review the NDA to assess the new drug candidate’s safety, efficacy, and quality, ensuring compliance with rigorous regulatory standards. Upon successful evaluation and approval of the NDA, the new drug can be introduced to the market.

3.9       Conducting Clinical Trials:

It is a critical phase in the drug development process, where investigational drugs are evaluated for safety, efficacy, and dosage in human subjects. These trials typically progress through several phases, starting with Phase 1 trials to assess safety and dosage, followed by Phase 2 trials to evaluate efficacy and side effects, and concluding with Phase 3 trials to confirm effectiveness and monitor adverse reactions in larger populations. Clinical trials adhere to strict protocols and are overseen by regulatory agencies and institutional review boards to ensure ethical conduct and patient safety.

3.10     Regulatory Approval:

The regulatory approval process involves the submission of comprehensive documentation, including clinical trial data, manufacturing information, pharmacological and toxicological studies, and proposed labeling and packaging. Regulatory agencies meticulously review this information to assess the new drug candidate’s safety, efficacy, and quality, ensuring compliance with stringent regulatory standards. Upon successful evaluation and approval, the new drug is granted marketing authorization, allowing patients to access innovative treatments while maintaining high standards of safety and efficacy.

4         Drug Efficacy on the Human Body

Drug efficacy refers to the ability of a pharmaceutical compound to produce a desired therapeutic effect in the human body. It is a crucial aspect of drug development and clinical practice, directly impacting the treatment outcome for various medical conditions. The efficacy of a drug is determined by its pharmacological properties, mechanism of action, and interaction with biological targets or pathways (Prestwich, 2008). Upon administration, drugs exert their effects by modulating specific biochemical or physiological processes, such as enzyme inhibition, receptor activation, or signal transduction. The extent of drug efficacy can vary depending on factors such as dosage, patient characteristics, disease severity, and genetic variability.

Conclusion

Drug discovery and development are complex and multifaceted processes that play a critical role in advancing healthcare and improving patient outcomes. Through innovative research, collaboration between interdisciplinary teams, and the integration of cutting-edge technologies, scientists continue to identify novel therapeutic targets, design new drug candidates, and optimize treatment modalities. While the journey from initial discovery to market approval is challenging and fraught with uncertainties, the potential benefits of bringing effective and safe drugs to patients are immense. As the field of drug development evolves, driven by advancements in fields such as genomics, proteomics, and artificial intelligence, there is growing optimism for the development of personalized and precision medicine approaches that can address medical needs and contribute to the realization of healthier and longer lives for individuals worldwide.

References

Berdigaliyev, N., & Aljofan, M. (2020). An overview of drug discovery and development. Future medicinal chemistry, 12(10), 939-947.

Deore, A. B., Dhumane, J. R., Wagh, R., & Sonawane, R. (2019). The stages of drug discovery and development process. Asian Journal of Pharmaceutical Research and Development, 7(6), 62-67.

Prestwich, G. D. (2008). Evaluating drug efficacy and toxicology in three dimensions: using synthetic extracellular matrices in drug discovery. Accounts of chemical research, 41(1), 139-148.

Tamimi, N. A., & Ellis, P. (2009). Drug development: from concept to marketing! Nephron Clinical Practice, 113(3), c125-c131.