What is the correct order of testing when developing a new drug?

What is the correct order of testing when developing a new drug?

• A. In vitro, preclinical, clinical
• B. Preclinical, in vivo, clinical
• C. Clinical, in vitro, preclinical
• D. In vitro, in vivo, clinical

Answer: (A)

Testing a new drug follows a progression from lab bench experiments to animal studies to human trials. Start with in vitro work, where cells or biological molecules are used to assess basic activity, mechanism, dosing ranges, and potential toxicity without using living animals. If those results look promising, move into preclinical studies, which are nonclinical investigations that include in vivo experiments in animal models to evaluate safety, pharmacokinetics, biodistribution, and appropriate dose levels. Only after gathering this nonclinical safety and efficacy data do researchers proceed to clinical testing in humans, beginning with first-in-human safety evaluations and then broader efficacy studies. That’s why the sequence in vitro → preclinical → clinical is the best fit. In vivo studies are part of the preclinical stage, so listing them separately after in vitro but before clinical aligns with how nonclinical testing is organized. Skipping the explicit preclinical stage or placing clinical steps before nonclinical work would overlook essential safety and dosing data gathered before human trials.

Testing a new drug follows a progression from lab bench experiments to animal studies to human trials. Start with in vitro work, where cells or biological molecules are used to assess basic activity, mechanism, dosing ranges, and potential toxicity without using living animals. If those results look promising, move into preclinical studies, which are nonclinical investigations that include in vivo experiments in animal models to evaluate safety, pharmacokinetics, biodistribution, and appropriate dose levels. Only after gathering this nonclinical safety and efficacy data do researchers proceed to clinical testing in humans, beginning with first-in-human safety evaluations and then broader efficacy studies.

That’s why the sequence in vitro → preclinical → clinical is the best fit. In vivo studies are part of the preclinical stage, so listing them separately after in vitro but before clinical aligns with how nonclinical testing is organized. Skipping the explicit preclinical stage or placing clinical steps before nonclinical work would overlook essential safety and dosing data gathered before human trials.