Pharmacology is defined as the study of the interaction of chemical substances with living systems.
A chemical substance that acts on living systems through chemical processes, which is utilized for diagnosis, prevention and cure of an unwanted health condition ( by FDA)
3. Name and Define two main subdivisions of pharmacology
Pharmacokinetic: Absorption, Distribution, Metabolism, Excretion Pharmacodynamics: Pharmacological effects of drug; Mechanism of action
Pharmacokinetics is the study of the kinetics of drug. (absorption, distribution, metabolism and excretion)
2. Ion trapping
Cell membranes are less permeable to ionized compounds (water solubility)
3. First-pass effect
Before the orally administrated drug reaches the systemic circulation, the drug can be metabolized in the liver or intestines, resulting in a significant reduction of amount of unmetabolized drug reaching the systemic circulation. It reduce: amount of unmetabolized drug, bioavailability and drug effects.
Bioavailability is a measure of the fraction (F) of administered dose of a drug that reaches the systemic circulation in the unchanged form. BA=A/D x 100% (A: Total amount of drug in SC; D: Administrated dose)) * Bioavailability indicates the rate and extent of absorption into the circulation following extravascular administration of drugs.
Time it takes for a drug concentrations to decrease by one half. The half-life of a drug that follows first-order kinetics (linear pharmacokinetics) is independent of the amount or concentration and inversely proportional to the overall elimination rate constant.
The theoretical volume of plasma from which the drug is completely removed in unit time (ml/min). CLtotal = k x Vd. (k: elimination rate constant; Vd: apparent volume of distribution). Elimination clearance means to leave the body or to...
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