Journal of Drug Metabolism & Toxicology
Open Access

The Role of Drug Disposition in Personalized Medicine: Implications for Dosing and Efficacy

Marc Jenn^{* *}Correspondence: Marc Jenn, Department of Drugs and Medicine, São Paulo State Universit, Araraquara, Brazil, Email:

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Description

Personalized medicine is an innovative approach that customizes medical treatment to the individual characteristics of each patient. One key area of personalized medicine is the pharmacokinetics of drugs, which involves understanding how the body absorbs, distributes, metabolizes, and excretes drugs collectively referred to as drug disposition. The concept of drug disposition in personalized medicine is critical, as it helps ensure that patients receive the most appropriate drug, in the right dosage, and with the highest chance of therapeutic success while minimizing adverse effects. Drug disposition can vary widely among individuals, influenced by factors such as genetic makeup, age, gender, organ function and the presence of other drugs or diseases. This article examines how understanding drug disposition can lead to more effective and safer dosing strategies, particularly in the context of personalized medicine.

Efficacy of drug disposition

Drug disposition involves four main processes, which together determine the concentration of a drug in the body over time and influence its efficacy and safety:

Absorption: This is the process by which a drug enters the bloodstream after administration. Factors such as the drug’s formulation, the route of administration (oral, intravenous, etc.), and gastrointestinal pH can affect the absorption rate.

Distribution: After absorption, drugs circulate through the bloodstream to various tissues and organs. Distribution is influenced by factors such as blood flow, the drug’s ability to cross cellular membranes, and its binding to plasma proteins. Different tissues may have varying affinities for the drug, leading to concentration gradients across the body.

Metabolism: Drugs are typically metabolized in the liver, where enzymes, particularly cytochrome P450 enzymes (CYPs), transform drugs into metabolites. These metabolites can be either active or inactive and often have a different pharmacological profile from the parent compound. Metabolism plays a key role in determining the drug's duration of action and its potential toxicity.

Excretion: The final process in drug disposition is the elimination of drugs and their metabolites from the body, usually via the kidneys (urine) or the liver (bile). Excretion rate influences the drug's half-life and its therapeutic effectiveness.

Role of drug disposition in personalized medicine

Personalized medicine aims to tailor medical treatments based on individual characteristics to optimize therapeutic outcomes. Genetic factors, such as polymorphisms in drug-metabolizing enzymes and transporters, significantly impact drug disposition, resulting in variations in how individuals absorb, distribute, metabolize, and excrete drugs. By understanding these individual differences, healthcare providers can optimize drug dosing to enhance efficacy and minimize adverse effects. Pharmacogenomics is the study of how genetic variations influence drug response. Polymorphisms in genes encoding drug-metabolizing enzymes, transporters, and receptors can lead to significant differences in drug disposition and, ultimately, therapeutic outcomes. For instance, cytochrome P450 (CYP) enzymes play an important role in the metabolism of many drugs. Genetic variations in CYP enzymes can lead to altered drug metabolism rates, categorizing individuals as poor metabolizers, extensive metabolizers, or ultrarapid metabolizers. For example, the CYP2D6 enzyme metabolizes a wide range of drugs, including antidepressants, antipsychotics, and beta- blockers. Individuals with polymorphisms in the CYP2D6 gene may metabolize these drugs more slowly or rapidly, affecting drug efficacy and safety. Poor metabolizers may experience higher drug concentrations, leading to an increased risk of adverse effects. Ultra rapid metabolizers may have lower drug concentrations and reduced therapeutic effects, requiring higher doses. In such cases, pharmacogenomic testing can guide clinicians in choosing the right drug and dosage for the patient based on their genetic profile, improving both efficacy and safety. The role of drug disposition in personalized medicine is pivotal for improving drug efficacy, minimizing adverse drug reactions, and optimizing patient outcomes. Genetic variability, organ function, age, drug interactions, and gender differences all influence how drugs are processed and eliminated from the body. By incorporating this information into clinical practice, healthcare providers can make more informed decisions, select the most appropriate drugs, and fine-tune dosing strategies based on the individual characteristics of each patient. As the field of personalized medicine continues to evolve, a deeper understanding of drug disposition will be important to enhancing therapeutic outcomes and ensuring the safety of patients.