The stages through which a drug discovery/development project proceeds from inception to marketing and beyond are illustrated in the following text. From this outline, the complexity of the task of finding new therapeutic agents is evident:
• Identification of target disease, establishment of a multidisciplinary research team, selection of a promising approach, and decision on a sufficient budget. Initiation of chemistry, which normally involves synthesis based on available chemicals or collection of natural product sources. Start of pharmacology, includes suitable screening methods and choice of receptor binding and/or enzymatic assays.
• Confirmation of potential utility of initial class(es) of compounds in animals, focusing on potency, selectivity, and apparent toxicity.
• Analogue syntheses of the most active compounds, planned after careful examination of literature and patents. More elaborated pharmacology in order to elucidate mode of action, efficacy, acute and chronic toxicity, and genotoxicity. Studies of ADME characteristics. Planning of large scale synthesis and initiation of formulation studies. Application for patent protection.
These first project phases, which typically last 4-5 years, are followed by very time- and resource-demanding clinical, regulatory, and marketing phases, which normally last about 10 years:
• Phase I clinical studies, which include safety, dosage, and blood level studies.
• Phase II clinical studies focusing on efficacy and side effects.
• Phase III clinical studies, which involve studies of range of efficacy and long-term and rare side effects.
• Regulatory review.
• Marketing and phase IV clinical studies focusing on long-term safety.
• Very large-scale synthesis.
• Distribution, advertisement, and education of marketing and information personnel.
After these project stages from initiation to successful therapeutic application after approval, the patent protection expires, normally after 17-25 years, and generic competition becomes a reality.
This outline of a drug development project illustrates that, at best, it takes many years to introduce a new therapeutic agent, and it must be kept in mind that most projects are terminated before marketing, even at advanced stages of clinical studies.
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