PHARMACO-ECONOMICS OF MICRODOSING CLINICAL TRIALS IN DRUG DEVELOPMENT PROCESS

Microdosing means use of less than 1/100 th of the dose calculated to yield a pharmacological effect of the test substance to a maximum dose of <100 micrograms. Once a single compound is selected, preclinical studies are performed to evaluate a drug's safety, efficacy and potential toxicity in animal models. Microdosing methodology is referred to as a new viable 'tool' in the drug development 'toolbox'. In microdosing, extremely low, nonpharmacologically active doses of a drug are used to define the agent's pharmacokinetic profile in humans. These are "Micro-dose" studies and, with drug levels in the picogram to fentogram range, pharmacokinetics analysis requires Positron Emission Tomography (PET) or Accelerator Mass Spectrometry (AMS); techniques that rely on the assessment and analysis of radioisotopes incorporated into the test drug (e.g., 14 C). There are three steps of microdosing. The first step of microdose trials is designed to evaluate pharmacokinetics, bioavailability, metabolism and/or distribution of a drug or its metabolite. Microdosing helps in early pharmacokinetic evaluation of new drug molecules, which helps in the early selection of promising compounds. Unsuitable molecules can be eliminated earlier which reduces costs and avoids the unnecessary exposure of subjects in the trial to non-viable. The risk of human toxicity is less because of short duration administration. Regulatory requirements for microdosing trials are flexible and limited, which is an advantage compared to phase I. Microdosing may help both patients and the pharma industry with earlier availability of new test drugs, reduced failure of compounds at later stages and reduce the cost of drug development.