Bioavailability BA definition and objectives explain the rate and extent of drug absorption reaching systemic circulation. Bioavailability (BA) definition and objectives Definition of Bioavailability Bioavailability is defined as the fraction (F) of an administered drug dose that reaches systemic circulation in an unchanged form and is available for therapeutic action. It includes both: Extent of … Read more
Renal Clearance (Clᵣ) explains the volume of plasma cleared of a drug per unit time, key in pharmacokinetics and dosing. Renal Clearance (Clᵣ) is the volume of plasma cleared of a drug by the kidneys per unit time (mL/min or L/h). It evaluates kidney efficiency in drug elimination and helps determine appropriate drug dosing, especially … Read more
Factors Affecting Renal Excretion of Drugs include pH, protein binding, blood flow, drug solubility, and renal function. Factors Affecting Renal Excretion of Drugs Plasma Protein Binding Only free (unbound) drug is filtered. High protein binding may reduce filtration but can still be secreted via active transport. Urine pH and Drug Ionization Weak acids and bases … Read more
Renal Excretion of Drugs involves filtration, secretion, and reabsorption processes that remove drugs through the kidneys. Renal Excretion of Drugs After metabolism (or sometimes directly if they are already sufficiently water-soluble), drugs and their metabolites are excreted from the body. The kidneys are the primary route for most water-soluble agents. Basic Renal Anatomy & Physiology … Read more
Drug Metabolism (Biotransformation) involves enzymatic conversion of drugs into active or inactive metabolites for elimination. Drug metabolism is the enzymatic conversion of drugs into metabolites for easier elimination, primarily occurring in the liver but also in the kidneys, lungs, intestines, and plasma. Phases of Drug Metabolism Phase I (Functionalization Reactions) These reactions introduce or expose … Read more
Apparent Volume of Distribution explains drug distribution between plasma and tissues, guiding dosing and pharmacokinetics. Definition: The apparent volume of distribution (Vd) is a theoretical pharmacokinetic parameter that describes the distribution of a drug in the body. It represents the hypothetical volume in which a drug would need to be evenly distributed to match its … Read more
Plasma Protein Binding of Drugs affects free drug levels, distribution, efficacy, and elimination in pharmacokinetics. Mechanism of Plasma Protein Binding: Reversible Binding: Drugs form non-covalent interactions (e.g., hydrophobic, hydrogen bonding, electrostatic) with plasma proteins, maintaining a dynamic equilibrium between bound and free drug. Competition for Binding Sites: Multiple drugs can bind to the same site, … Read more
Tissue Protein Binding of Drugs influences drug storage, release, duration of action, and overall pharmacological effects. Tissue Protein Binding of Drugs Tissue binding refers to the interaction between drugs and intracellular, extracellular, membrane, or receptor proteins in various organs, affecting drug distribution and elimination. Mechanism of Tissue Protein Binding: Intracellular Binding: Drugs bind to intracellular … Read more
Factors Affecting Protein-Drug Binding include drug concentration, protein levels, affinity, and disease conditions. Protein-drug binding influences pharmacokinetics, pharmacodynamics, and drug efficacy. Several factors determine the extent and specificity of drug binding to proteins. 1. Drug Properties Chemical Structure Size, shape, and functional groups influence binding affinity. Similar drugs may compete for the same binding site. … Read more
Kinetics of Protein Binding describes drug–protein association and dissociation rates impacting pharmacokinetics and dynamics. Protein binding kinetics describes the interaction between a drug (D) and a protein (P) to form a drug-protein complex (DP). This process follows a reversible equilibrium: $D + P \;\rightleftharpoons\; DP$ Rate of Drug-Protein Binding The association and dissociation of drug-protein … Read more
