PHAR 402 Week 1 PDF

PHAR 402 (Biopharmaceutics and Pharmacokinetics) Basic Definitions and Terminologies Asst. Prof. Dr. Muhammad Sohail FACULTY OF PHARMACY CYPRUS INTERNATIONAL UNIVERSITY  Contents Biopharmaceutics Pharmacokinetics Clinical Pharmacokinetics Pharmacodynamics...

PHAR 402 (Biopharmaceutics and Pharmacokinetics) Basic Definitions and Terminologies Asst. Prof. Dr. Muhammad Sohail FACULTY OF PHARMACY CYPRUS INTERNATIONAL UNIVERSITY  Contents Biopharmaceutics Pharmacokinetics Clinical Pharmacokinetics Pharmacodynamics Toxicokinetics Measurement of Drug concentrations Sampling of Biologic Specimen Drug concentrations in Blood, plasma or serum Plasma level-time curve Generics and Brands Contents Generic equivalence Therapeutic equivalence Bioavailability Bioequivalence Pharmacokinetics and Its Parameters Protein Binding Biopharmaceutics Biopharmaceutics is the science that examines this interrelationship of the physicochemical properties of the drug, the dosage form in which the drug is given, and the route of administration on the rate and extent of systemic drug absorption.  Biopharmaceutics… The biopharmaceutics involves factors that influence: (1) the stability of the drug within the drug product, (2) the release of the drug from the drug product, (3) the rate of dissolution/release of the drug at the absorption site, and (4) the systemic absorption of the drug. A general scheme describing this dynamic relationship is described in figure: Biopharmaceutics… The study of biopharmaceutics is based on fundamental scientific principles and experimental methodology. Studies in biopharmaceutics use both in-vitro and in- vivo methods. In-vitro methods are procedures employing test apparatus and equipment without involving laboratory animals or humans. In-vivo methods are more complex studies involving human subjects or laboratory animals. Pharmacokinetics After a drug is released from its dosage form, the drug is absorbed into the surrounding tissue, the body, or both. The distribution through and elimination of the drug in the body varies for each patient but can be characterized using mathematical models and statistics. Pharmacokinetics is the science of the kinetics of drug absorption, distribution, and elimination (i.e., excretion and metabolism). The description of drug distribution and elimination is often termed drug disposition Pharmacokinetics… The study of pharmacokinetics involves both experimental and theoretical approaches. The experimental aspect of pharmacokinetics involves the development of biologic sampling techniques, analytical methods for the measurement of drugs and metabolites, and procedures that facilitate data collection and manipulation. The theoretical aspect of pharmacokinetics involves the development of pharmacokinetic models that predict drug disposition after drug administration. Pharmacokinetics… The application of statistics is an integral part of pharmacokinetic studies. Statistical methods are used for pharmacokinetic parameter estimation and data interpretation ultimately for the purpose of designing and predicting optimal dosing regimens for individuals or groups of patients. Clinical Pharmacokinetics During the drug development process, large numbers of patients are tested to determine optimum dosing regimens, which are then recommended by the manufacturer to produce the desired pharmacologic response in the majority of the anticipated patient population. However, intra- and interindividual variations will frequently result in either a subtherapeutic (drug concentration below the MEC) or toxic response (drug concentrations above the minimum toxic concentration, MTC), which may then require adjustment to the dosing regimen. Clinical Pharmacokinetics… Clinical pharmacokinetics is the application of pharmacokinetic methods to drug therapy. Clinical pharmacokinetics involves a multidisciplinary approach to individually optimized dosing strategies based on the patient's disease state and patient-specific considerations. The influence of many diseases on drug disposition is not adequately studied. Age, gender, genetic, and ethnic differences can also result in pharmacokinetic differences that may affect the outcome of drug therapy. The study of pharmacokinetic differences of drugs in various population groups is termed population pharmacokinetics. Pharmacodynamics Pharmacodynamics refers to the relationship between the drug concentration at the site of action (receptor) and pharmacologic response, including biochemical and physiologic effects that influence the interaction of drug with the receptor. The interaction of a drug molecule with a receptor causes the initiation of a sequence of molecular events resulting in a pharmacologic or toxic response. Pharmacokinetic-pharmacodynamic models are constructed to relate plasma drug level to drug concentration in the site of action and establish the intensity and time course of the drug. Pharmacokinetics vs Pharmacodynamics Toxicokinetics Toxicokinetics is the application of pharmacokinetic principles to the design, conduct, and interpretation of drug safety evaluation studies and in validating dose-related exposure in animals. Toxicokinetic data aids in the interpretation of toxicologic findings in animals and extrapolation of the resulting data to humans. Toxicokinetic studies are performed in animals during preclinical drug development and may continue after the drug has been tested in clinical trials. Clinical Toxicology Clinical toxicology is the study of adverse effects of drugs and toxic substances (poisons) in the body. The pharmacokinetics of a drug in an overmedicated (intoxicated) patient may be very different from the pharmacokinetics of the same drug given in lower therapeutic doses. At very high doses, the drug concentration in the body may saturate enzymes involved in the absorption, biotransformation, or active renal secretion mechanisms, thereby changing the pharmacokinetics from linear to nonlinear pharmacokinetics. THANK YOU FOR LISTENING