Phase 1- 4

Phase Description Sample size Approaches Objectives
I Define doses and dosing frequency that applicable for a particular study with reference to pharmacokinetic data. Most likely a controlled laboratory experiments than population-based clinical trials. Narrow scale of healthy volunteers (generally ~ 20 subjects)
  1. Mircrodose trials at total dose ≤ 100 μg.
  2. Microdose trials at cumulative dose ≤ 500 μg.
  3. Single Dose Studies at Sub – therapeutic Doses or into the Anticipated Therapeutic Range.
  4. Dosing up to 14 days into the therapeutic range but not intended to evaluate clinical MTD.
  5. Dosing up to 14 days and not to exceed duration of dosing in non- rodent; into therapeutic range but not intended to evaluate clinical MTD.
  1. Estimation of Initial safety and tolerability.To determine tolerability of dose range for later stage and to determine the nature of adverse reactions.
  2. Pharmacokinetic.ADME study with priority to determine clearance of product and possibility accumulation of parent drug and metabolites as well as potential drug-drug interaction.
  3. Assessment of pharmacodynamic.Studies of drug blood levels to response (PK/PD studies).
  4. Early measurement of drug activity.Preliminary study of drug benefit.


Investigates the occurrence of possible clinical benefits and existence of side effects. The trial sometimes is set up to screen for few drugs with genuine potential.    Small scale of homogenous patients that usually conducted at one site (generally ~ 100-200 subjects but it is advised that sample size is calculated for specific studies) Dose-escalation design

Parallel dose-response design
To evaluate for efficacy and safety profile for drug’s therapeutic indication, potential study endpoints, therapeutic regimens and potential target populations


A well randomized controlled clinical trial research program for a new drug evaluation to conclusively demonstrate the efficacy of the investigational drugs in a population by means of compilation of all clinical trials results in this phase into one package evidence to be presented to the regulatory authority for approval. Large scale of patients presenting diseases symptoms that usually conducted at multiple study sites (generally > 200 subjects but it is advised that sample size is calculated for specific studies) Dose-response relationship in:

  • wider population (multiple site)
  • different stages of disease
  • combination with other drugs
To confirm preliminary evidence accumulated in Phase II.


A trial of products that already have marketing authorization. Studies may be undertaken to expand the indications listed on a marketing authorization either for a different diseases or to gain more safety data for newly registered product. Post-marketed product Additional:

  • Drug-drug interaction studies
  • Dose-response
  • Safety studies
To support use under the approved indication.
in this scope