Drugs: From Discovery to Approval

Rick Ng

3 ideas

1. Phased Clinical Trial Risk Escalation

   Human drug testing proceeds through sequential phases that escalate exposure as evidence accumulates: Phase I tests safety and dosing in a small group of healthy volunteers, Phase II tests efficacy and side effects in a few hundred patients with the target condition, and Phase III confirms efficacy in thousands across diverse sites. Each phase is a gate that must demonstrate acceptable safety before the larger, more expensive next phase is permitted, concentrating early risk on small populations.

2. Therapeutic Index Separates Dose from Poison

   A drug's safety margin is quantified by the ratio between the dose that produces toxicity and the dose that produces the desired effect. A wide therapeutic index means the effective dose is far below the harmful dose, allowing forgiving dosing; a narrow index means small dosing errors can shift a patient from cure to harm, requiring tight monitoring.

3. Most Drug Candidates Fail Before Market

   Of thousands of compounds screened in discovery, only a tiny fraction survive preclinical and clinical testing to reach approval, with attrition occurring at every stage due to toxicity, poor efficacy, or unfavorable pharmacokinetics. This high failure rate is the central economic reality driving the enormous cost and decade-plus timeline of bringing a single drug to patients.

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