New Drug Development & Approval Process

Definition & overview of the pipeline

• "New drug" (regulatory sense) — a chemical or biological agent becomes a "legal drug" only when approved by a national regulator — the US FDA, the EU EMA, or in India the Central Licencing Authority (CLA)/CDSCO.
• NDCT-2019 definition (India) — a drug is "new" if it is any of: (i) not used in India to any significant extent & not CLA-approved; (ii) an approved drug with a new indication/route/dose/dosage form; (iii) a fixed-dose combination made for the first time; (iv) a modified/sustained-release form or NDDS; or (v) a vaccine, r-DNA product, monoclonal antibody, cell/stem-cell or gene-therapy product — status persists 4 years [(iv)–(v) always "new"]. [CDSCO]
• NCE / NME — a new chemical/molecular entity is a novel molecule never approved as a drug by any regulator, proposed for first-time development by establishing its safety & efficacy.
• Scale & attrition — the process is arduous, technical and costly — only ~1% of compounds entering full testing reach the market; cost ~$1–4 billion per NME over a timeline that may exceed 15 years (up to ~10 years clinical).
• Drug "invention" — Brunton frames modern practice as drug invention rather than discovery — most new drugs are "totally new compounds painstakingly optimised" by design + experimentation, not natural products.
• Pipeline at a glance — Discovery / lead optimisation → clinical candidate → preclinical (PD/PK/toxicology) → IND (US) / CT-permission (India) → Phase I → II → III → NDA/BLA (US) / import-or-manufacture permission (India) → marketing approval → Phase IV post-marketing surveillance.