Taking a look at the current scenario, it can be said that to give birth to a new drug, a pharmaceutical researcher must focus on two different aspects – discovery and development. Under drug discovery, the preliminary task is to generate a hypothesis leading of receptor target for a particular disorder. This is followed by in-vitro screening coupled with in-vivo biological activities of the investigational drug products. Whereas, the drug development phase assesses both efficacy and toxicity levels of the new molecular entity.
To facilitate both the drug discovery and development program, pharmacokinetics and metabolism assessment is crucial. A comparative result of both studies decides whether the new drug development process has succeeded or failed. The initiation of an early ADME (Absorption, Distribution, Metabolism, and Excretion) screening has completely wiped off the ill effects of the clinical trial failure. The preliminary result behind the evolution of this ADME screening was to eliminate all the weak drug candidates from the initial phase of the clinical trials itself. This would indirectly focus more on enhancing the productivity and reliability of the potent drug candidates.
Various undesirable pharmacokinetic parameters are contributing to the failure of the drug candidates in its early screening stage. The most potent amongst these factors are – too long or too short shelf-life, poor absorption, and extensive first-pass metabolism. So, to manufacture a potent drug, the pharmaceutical researcher must re-direct his focus more on its desirable half-life as well as bioavailability.
In such a scenario, the data obtained from the ADME pharmacokinetics may be useful in screening the right candidates for the preclinical procedure; selecting appropriate dosage forms and formulations; accelerating the drug investigation timeline for researching a new drug formulation; and thereby facilitating the submission of the new drug application.
Likewise, it is equally essential for pharmaceutical researchers to extrapolate the ADME assay parameters. The data obtained from these pharmacokinetic studies will surely pave a way to the future clinical trials using animal studies and aid in the selection of particular dosage form and the frequency of its administration.
What data do the ADME studies provide the pharmaceutical researcher with?
ADME pharmacokinetic studies deal with the parameters of absorption, distribution, metabolism, elimination, and toxicity of a particular pharmaceutical product. It answers the following questions –
- What quantity of the drug substance is absorbed by the target body and its time interval?
- (Absorption – bioavailability)
- Where and how is the drug being distributed throughout the target body system? It also defines the rate and extent of drug distribution. (Distribution)
- How long does it take for a particular pharmaceutical product to undergo metabolism within the target body? What is its mechanism of action once it is distributed throughout the target body? (Metabolism)
- The mechanism of elimination of the pharmaceutical product from the human body. (Elimination)
- Does the pharmaceutical drug or any of its excipients produce any toxic effects on the body of the target species? (Toxicity).
In short, the ADME assays and pharmacokinetic studies are a crucial part of the regulatory check to grant the manufacturer a right to commercialise his medicinal product.
