In compound-centered drug design, which statement is true?

• A. The compound/potential drug is identified first.
• B. The target is identified first.
• C. The disease is treated with existing drugs only.
• D. The screening assays are not used.

Answer: (A)

In compound-centered drug design, the emphasis is on discovering a compound with the desired biological effect before knowing how it works. This approach, often called phenotypic drug discovery, starts by screening large libraries of chemicals in biological assays to identify hits that produce the therapeutic effect. Those hit compounds are then optimized through medicinal chemistry to improve potency, selectivity, and pharmacokinetic properties. The molecular target or mechanism may be unknown at first and is usually determined later through target deconvolution. This is different from starting with a known target and designing molecules to interact with it. Screening assays are essential in this approach because they reveal which compounds produce the desired effect, making the first true step identifying the compound/potential drug.