Pharmacodynamic Evaluation: Gastroenterology

Abstract

Pharmacodynamics aims to explain the complex relationship between the medication’s dose, physiological or pathological response, and the chemical nature of the drug. The human gastrointestinal tract (GIT) is a strictly hierarchic body system with numerous functions and is often a therapeutic target, crosslink, or can even serve as a measurement for drug’s physiologic and biochemical effects. The pharmacological effects and the pharmacodynamics evaluation in the GIT would not have been possible without three distinct receptor families that have been known to have an enormous role in the modulation of the GIT functions: serotonergic, cannabinoid, and opioid receptors. In addition, the route of administration can be of great importance for the absorption and pharmacological response of the drug and there are several main routes of administration in gastroenterology: oral, parenteral, transmucosal, and local. Furthermore, a targeted and individualized approach for drug monitoring was developed that takes into account individual patient variability through careful gathering of pharmacokinetic and pharmacodynamic data: therapeutic drug monitoring, allowing to really individualize patient’s dose. Various novel imaging methods are used in gastroenterology, e.g., PET scan, MRI, and molecular endoscopy, and they all use tracers and contrast agents. They allow for early an accurate detection of various lesions in the GIT. Current understanding of oral tolerance has allowed the development of two groups of medications with a unique pharmacodynamic profile: oral vaccines, inducing immune response and oral tolerogens, initiating immunomodulation with alteration of immune response directed at the development of local and/or systemic immune tolerance.