Table 1. Steps in the development of active pharmaceutical ingredients (APIs) toward clinical use
PhaseSubphaseActivitiesOutcomes
Lead optimization (non‐GLP)In vitro ADMEChemical stability, solubility, metabolic stability, stability in gastric environment, CYPs interaction, PPB, BBB permeabilityInformation required for the final selection of the lead compound; it is usually performed on a group of the most potent hit analogs developed during the hit‐to‐lead screen
In vitro toxicologyCytotoxicity, hepatotoxicity, cardiotoxicity, mutagenicity
In vivo ADMEPharmacokinetics: (oral) bioavailability, plasma exposure, tissue distribution, metabolism, excretion
Metabolite profilingN.a.Profiling and identification of metabolites formed in hepatocytes of humans and animal species used for non‐clinical safetyAllows the selection of animal species for further in vivo toxicology studies
Synthesis scale‐up (GMP)N.a.Synthesis of a large batch of API in a GMP fashionA GMP batch of API produced in quantity sufficient to cover the toxicology and First‐in‐Human studies
CMC of the APIN.a.Validation of API chemical structure; determination of physicochemical parametersMandatory information for IB/IMPD or IND filling and for formulation development
API stabilityN.a.Stability study of the API under ICH conditionsExpiry date of the API in different storage conditions
Pre‐formulation and stability of drug productN.a.Selection of the formulation based on physicochemical properties of the API and desired route of administration; determining API stability in the formulationOptimal formulation and stability data to support GLP toxicology and First‐in‐Human studies
GLP‐compliant API detection methodsN.a.Validation of a GLP‐compliant method to quantify the API in dose formulation studies and biological fluidsGLP‐compliant and validated method to detect and quantify API during toxicology and First‐in‐Human trials
Non‐clinical safetyPilot toxicology studyDose range finding and 14‐day toxicology study in a single animal speciesFirst information on the dose range and specific toxicity to be monitored during the next phases
GLP‐compliant regulatory toxicology studyIn vitro: GLP‐compliant in vitro toxicology studyGenetic toxicology, safety pharmacology
In vivo: GLP‐compliant in vivo toxicologyGeneral toxicology
In vivo: reproductive toxicology studyAdverse effects on embryonic development
In vivo: juvenile toxicology studySpecific adverse effect on juvenile population
Drug–drug interaction studyN.a.Inhibition and substrate potential of API toward CYPs, drug transporters, and UGTsPrediction of potential adverse effect arising from polypharmacology (i.e., how others drugs and API will impact on each other's ADME properties leading to modified PK/PD profile)
Investigational brochure (IB)N.a.Compile all preclinical data relevant to study the API in humans under ICH conditionsThe IB is required for the clinical investigator to design the clinical trial protocol
Investigational medical product dossier (IMPD)N.a.Complete the IMPD form with CMC information about drug substance and drug productThe IMPD is required for authorization to enter First‐in‐Human trials
Clinical trial application (CTA) formN.a.Complete CTA with information about drug product and trial design, site and investigatorThe CTA is required to obtain authorization to enter First‐in‐Human trials
  • This table summarizes the overall preclinical experimental and administrative steps required for a novel API to entering First‐in‐Human trials. It is based upon experiences within our SME Khondrion and is not intended to be exhaustive. Each API will have a specific development path, and API developers should strictly follow the guidance and requirements from the official agencies involved.

  • ADME, absorption, distribution, metabolism, and excretion; API, active pharmacological ingredient; BBB, blood–brain barrier; CMC, chemistry and manufacturing controls; CTA, clinical trial application; GLP, good laboratory practices; GMP, good manufacturing practices; CYP, cytochrome P450; IB, investigational brochure; ICH, The International Conference on Harmonisation (of Technical Requirements for Registration of Pharmaceuticals for Human Use); IMPD, investigational medical product dossier; IND, investigational new drug; N.a., not appropriate; PD, pharmacodynamics; PK, pharmacokinetics; PPB, plasma protein binding; UGT, UDP glucuronosyltransferase.