Pharmacokinetics & Pharmacodynamics in Drug Discovery

Pharmacokinetics & Pharmacodynamics in Drug Discovery

An essential part of your drug development plan is to establish that your compound is safe and effective. Well-designed Pharmacokinetic trials (which determine how the body affects the drug) measuring plasma levels of varying doses across time, provide you with the knowledge to plan well-controlled later phase trials with different doses, or dosing regimens, to evaluate how the drug affects the body (Pharmacodynamics) and establish safety and efficacy.

Role of Clinical Trial Pharmacokinetics & Pharmacodynamics in Drug Discovery

Pharmacokinetics and Pharmacodynamics modeling and approaches have been a part of clinical research and development since the 1980s. Pharmacokinetics (PK) and Pharmacodynamics (PD) are two broad divisions of pharmacology that provide a better understanding of drug efficiency and safety. Both pharmacokinetics and pharmacodynamics investigations are mandatory for the drug development process as both are fundamental requirements for the clinical usage of drugs.


What is Pharmacokinetics?

Pharmacokinetics (PK) is a branch of pharmacology that attempts to analyze how your body reacts soon after the absorption of a drug or substances such as pharmaceutical drugs, cosmetics, food additives, pesticides, and much more. It also refers to how and where the drug/substance is distributed throughout your body once it is administered, and how your body metabolizes the drug and eliminates it.

Pharmacokinetics involves the analysis of four processes:

  • Absorption: It refers to the movement of drugs or substances into the blood soon after a drug or substance is administered to the patient.
  • Distribution: It is the process of disseminating the drug throughout the tissues and fluids of the body.
  • Metabolism: It is the process of irreversible conversion of parent compounds into daughter metabolites. Before getting eliminated from the human body, the drug is metabolized by the liver or kidneys to make the drug more water-soluble to facilitate drug inactivation or excretion.
  • Excretion: It is the process of eliminating the drug from the human body.

In other words, clinical Pharmacokinetics is used for measuring the rate of a drug/medicine’s absorption, distribution, metabolism, and excretion. The key objective of pharmacokinetics is to enhance efficiency and minimizing the harmful effects of patients’ drug therapy. Application of Pharmacokinetics principles is highly beneficial for prescribers as it goes a long way towards helping them in adjusting drug dosage more accurately.


What is Pharmacodynamics?

Pharmacodynamics (PD) analyzes the complex interactions between your body and the drug. While Pharmacokinetics emphasizes the movement of a drug within your body, Pharmacodynamics refers to the molecular, physiological, and biochemical effects of the drug on your body. It is the interconnection between drug concentration at the site of drug action and the aftereffect, along with the timeframe and magnitude of curative and adverse effects.


Importance of Pharmacokinetics and Pharmacodynamics for Drug Companies and Patients

  1. Without Pharmacokinetics and Pharmacodynamics investigation of a drug, regulatory agencies would not approve its use. Thus, both PK and PD, in combination with FDA-approved standards, play a crucial role in drug discovery and determining the success or failure of drugs’ approval. What’s more, both PK and PD also make use of sophisticated data analysis tactics for estimating parameters of interest.
  2. Both Pharmacokinetics and Pharmacodynamics principles are applied to facilitate safe and efficacious therapeutic management of patients. It is important for patients with chronic disease, to understand the significance of PK/PD as they play a major role in determining the success or failure of the prescribed drug treatment.
  3. Similarly, drug companies also depend significantly on Pharmacokinetics and Pharmacodynamics, along with the sophisticated programming tools required for the success of their clinical trials.


Pharmacokinetics elucidates a drug’s exposure, whereas Pharmacodynamics reveals the response of the drug in terms of biochemical interactions. Comprehending the correlation between exposure and response is crucial to the formulation and approval of every drug.

  • Pharmacokinetics and Pharmacodynamics analyses help describe drug exposure: Quantifying the intensity of drug exposure is necessary for identifying the best and safest way to make use of it in the clinic.
  • Presume dosing requirements: Pharmacokinetics and Pharmacodynamics analyses help researchers deduce dosage requirements early in the drug development procedure.
  • Evaluate modifications in dosing requirements: Alterations in the formulation of drugs are quite common in the early stage of drug development. Therefore, it is essential to forecast the biological impact of minor dosage changes early in the drug development process.
  • Guesstimate the rate of absorption/elimination: Pharmacokinetics and Pharmacodynamics principles help researchers understand how quickly a body absorbs and eliminates drugs so that they can make decisions pertaining to drug formulation and dosage requirements.
  • Comprehend concentration-effect interrelationships: Since the concentration-effect relationship is the foundation of PD, it is essential to identify the variables affecting the relationship to facilitate a successful drug development program.
  • Determine Safety Margins: Pharmacokinetics and Pharmacodynamics modeling help analyze dosing thresholds to determine the safety of the drug and identify maximum tolerated dosage.

Pharmacokinetics and Pharmacodynamics modeling play a crucial role in the discovery of new medicines in the pharmaceutical industry. Both PK and PD have their unique significance in each step of medicine development and demonstrate their usefulness in treating several ailments. That’s why their importance is becoming recognized worldwide for conducting successful clinical trials.


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