Pharmacodynamics and pharmacokinetics Flashcards
Define pharmacodynamics
Pharmacodynamics refers to how a drug affects the body, including its mechanisms of action, the relationship between drug concentration and effect, and the therapeutic and toxic effects of the drug.
Define pharmacokinetic
Pharmacokinetics involves the absorption, distribution, metabolism, and excretion (ADME) of drugs within the body
explain the pharmacokinetic phases that drugs pass-through
Absorption: The process by which a drug enters the bloodstream. It can occur through various routes such as oral (through the gastrointestinal tract), intravenous (directly into the bloodstream), etc.
Distribution: The movement of a drug from the bloodstream to various tissues and organs of the body. Factors influencing distribution include blood flow to tissues, drug solubility, and tissue permeability.
Metabolism: The biochemical transformation of drugs into metabolites, often occurring in the liver (although other organs can also metabolize drugs). Metabolism can either activate, deactivate, or modify the chemical structure of the drug.
Excretion: The elimination of drugs and their metabolites from the body, primarily through the kidneys (via urine) or through bile (into feces).
what are the 4 Pharmacokinetic Phases:
Absorption, Distribution, Metabolism, Excretion
Outline the factors that affect drug absorption
Route of administration: Determines how and where the drug enters the body.
Drug formulation: Different formulations (e.g., tablets, capsules, liquids) affect absorption rates.
Blood flow to the site of administration: Influences the rate of absorption.
Surface area available for absorption: Larger surface areas (e.g., in the lungs) can increase absorption.
pH and acidity: Can affect drug ionization and absorption in the gastrointestinal tract.
Describe the characteristics of different routes of drug administration.
Oral: Easy, convenient, but subject to variable absorption due to gastrointestinal factors.
Intravenous: Immediate and complete absorption, suitable for emergencies.
Inhalation: Rapid absorption into the bloodstream through the lungs, useful for respiratory conditions.
Topical: Applied directly to the skin or mucous membranes, providing localized effects.
Subcutaneous and intramuscular: Absorption rates vary depending on blood flow and drug formulation.
what are the different routes of drug adminsteration
Oral (also called enteral)
Sublingual
Parenteral:
Subcutaneous
Intramuscular
Intravenous
Inhalation
Topical
Rectal
Describe the hepatic first-pass effect and how it influences bioavailability
This effect refers to the metabolism of a drug in the liver before it reaches systemic circulation. It can significantly reduce the bioavailability (the amount of drug that reaches the systemic circulation unchanged) of orally administered drugs.
Discuss factors influencing drug absorption, distribution, metabolism and excretion
Physiological factors: Age, sex, genetics, and overall health.
Drug factors: Chemical properties, formulation, and dosage.
Environmental factors: Diet, smoking, and concurrent medications.
Pathological factors: Liver or kidney disease can affect metabolism and excretion.
Discuss individual patient factors that may influence drug absorption, distribution, metabolism and elimination
These include genetic variations in drug metabolism enzymes, renal function (which affects drug excretion), liver function (which affects drug metabolism), and body composition (which affects drug distribution).
Differentiate between potency and efficacy in pharmacodynamics.
Potency: Refers to the amount of drug required to produce a certain effect. A more potent drug requires a lower dose to achieve the desired effect.
Efficacy: Refers to the maximum effect that a drug can produce, regardless of dose. It indicates how well a drug can achieve its desired therapeutic effect.
Define drug half-life
Drug half-life is the time required for the concentration of a drug in the bloodstream to reduce to half of its original level.
explain the clinical application of drug-half life
The concept of drug half-life is clinically significant as it helps determine dosing schedules, ensures effective drug levels are maintained in the body, and minimizes the risk of side effects and toxicity by guiding how frequently a medication should be administered and how long it will take for the drug to be eliminated from the body.
Discuss the differences between an agonist and an antagonist.
Agonist: A drug that binds to a receptor and activates it, producing a biological response.
Antagonist: A drug that binds to a receptor but does not activate it, blocking the receptor from being activated by agonists.
define bioavailability
Bioavailability is the proportion of a drug or other substance that enters the bloodstream when it is introduced into the body and is made available for use or storage.
