Pharmacokinetics (PK) describes how an active substance behaves over time in the organism: how it is absorbed, distributed, metabolized, and excreted. It provides concentration and exposure data, on the basis of which dose, dosing interval, and the investigation of special patient populations are planned. In clinical development, it links non-clinical findings with the medicinal product concentrations observed in humans.<\/p>\n
The four classic sub-processes are summarized as ADME: absorption, distribution, metabolism, and excretion. Absorption determines the extent and rate at which an active substance enters the circulation from the site of administration. Distribution describes the distribution between blood and tissues. Metabolism comprises the enzymatic conversion of the parent compound; its products can be independently relevant for efficacy, safety, or analysis. Excretion refers to the elimination of the active substance and metabolites, for instance renally or biliary.<\/p>\n
PK investigations do not solely consider the unchanged active substance. Depending on the question, metabolites, the influence of the pharmaceutical form, food, concomitant medication, or impaired organ functions must also be classified. Non-clinical PK and toxicokinetic data from the species used for safety studies are an important reference point for the transition to early clinical trials. They help to put the exposure expected in humans into relation with non-clinical safety findings.<\/p>\n
Pharmacokinetic parameters are derived from serial samples and a concentration-time curve. The area under the curve, AUC, describes the total systemic exposure over the observed period. Cmax is the highest observed concentration, Tmax its time of occurrence. Clearance denotes the elimination capacity related to a hypothetical plasma volume per time; the apparent volume of distribution supports the description of the distribution outside the plasma. The elimination half-life indicates the time in which the concentration in the terminal phase falls by half.<\/p>\n
These parameters should not be evaluated in isolation. With an approximately linear kinetics, the exposure within the investigated range changes approximately proportionally to the dose. Saturable metabolism, transport processes, or time-dependent changes, in contrast, can lead to non-linear kinetics. Then a transfer of concentrations between dose levels must be particularly carefully justified. For robust parameters, a sampling plan suitable for the expected profile, a validated bioanalytical method, and the documented handling of missing values or values below the limit of quantification are required.<\/p>\n
With multiple dosing, it must also be investigated whether concentrations build up to a steady state and whether the kinetics after repeated administration deviate from the single-dose profile. Such findings influence the choice of the dosing interval and the observation period.<\/p>\n
Pharmacokinetics answers the question of which concentrations the body is exposed to after administration and how these concentrations arise and subside. Pharmacodynamics, in contrast, investigates the biological or clinical effects of an active substance, its mechanism of action, and the relationship between exposure or dose and effect. PK thus provides the course of exposure; PD classifies which desired and adverse effects are associated with it.<\/p>\n
In PK\/PD models, both perspectives are deliberately linked. A concentration alone does not prove a therapeutic effect, and an observed effect does not explain without exposure data whether differences are due to absorption, elimination, or sensitivity, for example. The separate collection and joint interpretation therefore support a scientifically justified dose selection.<\/p>\n
In First-in-Human and other early trials, PK data are compared with non-clinical pharmacological, toxicological, and toxicokinetic information. The EMA expects a scientific justification of the starting dose, dose escalation, and maximum exposure for risk identification and mitigation. Later, concentration data help to describe dose-response and dose-safety relationships and to examine the influence of covariates such as body weight, age, or organ function. Errors in time windows, sample processing, or the bioanalytical chain can substantially weaken these conclusions.<\/p>\n
Full-service CROs such as Mediconomics support PK sampling planning, the coordination of laboratory and logistics processes, data management, as well as the analysis and reporting of pharmacokinetic data. This includes the coordination of sampling at the study site, the monitoring of protocol-compliant time windows, the consolidation of clinical and laboratory information, and the preparation of tables, listings, and interpretations for clinical study reports.<\/p>\n
What does AUC stand for in pharmacokinetics?<\/strong><\/p>\n AUC stands for the area under the concentration-time curve. It is used as a measure of systemic exposure and complements parameters such as Cmax and Tmax.<\/p>\n Why are PK data important in the case of impaired renal or hepatic function?<\/strong><\/p>\n Altered elimination or metabolic processes can increase or decrease exposure. Such data contribute to justifying appropriate dosage recommendations or restrictions on use.<\/p>\n Is bioavailability the same as exposure?<\/strong><\/p>\n No. Bioavailability describes the proportion and rate at which an active substance becomes systemically available after extravascular administration. Exposure is described, among other things, by the concentration-time curve and its AUC.<\/p>\n Pharmacokinetics (PK) describes how an active substance behaves over time in the organism: how it is absorbed, distributed, metabolized, and excreted. It provides concentration and exposure data, on the basis of which dose, dosing interval, and the investigation of special patient populations are planned. In clinical development, it links non-clinical findings with the medicinal product […]<\/p>\n","protected":false},"author":10,"featured_media":0,"parent":0,"template":"","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"glossary-cat":[],"class_list":["post-6702","glossary","type-glossary","status-publish","hentry"],"acf":[],"related_terms":"","external_url":"","internal_reference_id":"","_links":{"self":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6702","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/types\/glossary"}],"author":[{"embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/users\/10"}],"version-history":[{"count":1,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6702\/revisions"}],"predecessor-version":[{"id":7442,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6702\/revisions\/7442"}],"wp:attachment":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/media?parent=6702"}],"wp:term":[{"taxonomy":"glossary-cat","embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary-cat?post=6702"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Regulatory references<\/h2>\n
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