Lab 3: Clinical Parameters in Drug Pharmacokinetics PDF

# WASIT UNIVERSITY - COLLEGE OF DENTISTRY ## PRACTICAL PHARMACOLOGY ## DENTAL 3rd STAGE ### Clinical Parameters in Drug Pharmacokinetics By: Dr. Reham Najem Abdulridha - **Pharmacokinetics:** ("what the body does to the drug"). * **ADME:** Absorption, Distribution, Metabolism, Elimination...

# WASIT UNIVERSITY - COLLEGE OF DENTISTRY ## PRACTICAL PHARMACOLOGY ## DENTAL 3rd STAGE ### Clinical Parameters in Drug Pharmacokinetics By: Dr. Reham Najem Abdulridha - **Pharmacokinetics:** ("what the body does to the drug"). * **ADME:** Absorption, Distribution, Metabolism, Elimination * **Drug at Site of Administration** * **Absorption:** (Input) First, absorption from the site of administration permits entry of the drug (either directly or indirectly) into plasma. * **Distribution:** Second, the drug may then reversibly leave the bloodstream and distribute into the interstitial and intracellular fluids. * **Metabolism:** Third, the drug may be biotransformed by metabolism by the liver or other tissues. * **Elimination:** (Output) Finally, the drug and its metabolites are eliminated from the body in urine, bile, or feces. - **Pharmacokinetic parameters allow the clinician to design and optimize treatment regimens, including decisions as to:** * the route of administration for a specific drug * the amount and frequency of each dose * the duration of treatment - **Dose Response Curve** * A dose-response curve is a simple X-Y graph relating the concentration or amount or dose of a drug, to the response of the receptor or the drug effect. * The measured dose is generally plotted on the X axis and the response is plotted on the Y axis. * **ED50:** The dose of a medication that produces a specified effect in 50% of the population. - **Drug will typically interact with receptor protein** - **The most important pharmacokinetic parameters are:** * **Area under the Drugs Concentration Curve(AUC):** If a plot of the plasma drug concentration versus time is made, then the area under this curve (AUC) represents the total amount of drug absorbed. This parameter is very important in defining how well the drug is absorbed, and is required by the FDA in the drug approval process. The usual unit is mg*h/ L. * **Bioavailability(BA, F):** is the fraction of administered drug that reaches unchanged to the systemic circulation. * **Bioavailability** = AUC(oral)/ AUC(IV) X 100 * **Drug Concentration (C):** is the amount of drug in a given volume of plasma. The usual uni is mg/l. * **Volume of Distribution (Vd):** The volume of distribution is a kinetic parameter that is used to estimate the degree to which a drug permeates the different fluid compartments of the body. It is defined as the amount of drug in the body divided by the concentration of drug in the blood or plasma. The usual unit is L. * Vd = Total amount of drug in the body (A)/ Drug plasma conc. (C) * **Clearance:** Is the volume of plasma cleared of the drug per unit time. The usual units are ml./min. or L./h. * The total body clearance = renal clearance + hepatic clearance + lung clearance etc... * **Elimination rate constant (Kel):** is the rate at which a drug is removed from the body. The usual unit is h-1. * Kel= CL/Vd * **Elimination half-life (t1/2):** This is the period of time required for the concentration or amount of drug in the body to be reduced by one-half. * t1/2 =0.6931 Kel # Thank You