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Pharmacokinetics vs Pharmacodynamics

Pharmacokinetics vs Pharmacodynamics: Definition & Importance

The goal of the regulatory review process is to determine whether the drug will be safe, effective, and acceptable for use by the patients. However, determining safe and effective quickly is no easy task. The process involves a multi-stage analysis of the clinical data with careful consideration of all data points including the potential risks and benefits. The FDA has a comprehensive set of review criteria that are applied to each new drug application (NDA) or biologic license application (BLA). The drug discovery development process generally follows these steps:

  1. Prescription Drug User Fee Act (PDUFA) Action Letter

The first step in the development of any new drug is a PDUFA action letter from the FDA, which sets forth an agency response to each NDA or BLA and provides recommendations on how the agency may move forward with its programmatic actions. A PDUFA action letter is based on the level of significance of any new drug in relation to other drugs on the market, as well as its potential safety risks and therapeutic effectiveness.

  1. New Drug Application (NDA) Submission

Once the PDUFA action letter is received by the applicant, it is reviewed by a scientific review division working within the Center for Drug Evaluation and Research (CDER). 

Pharmacokinetics vs pharmacodynamics is a division of biochemical pharmacology which defines the relationship between plasma and tissue drug and metabolite concentrations, time, and biological response. The goal of pharmacodynamics studies is to understand what the drug does to the body in terms of therapeutic response and toxicity. Pharmacodynamic studies are often evaluated in tandem with PK analysis to better understand the relationship of exposure and effect and the timing of therapeutic or toxicological responses. PK assays in target tissues are often performed to better understand the and serum or plasma to better understand the relationship of systemic and target tissue exposures and the relationship between exposure and response, referred to as the PK/PD relationship.