Pharmacology: Chapter 2 Drug Action And Handling Flashcards
What is a drug?
A biologically active substance that can modify cellular function
What is the potency of a drug?
the amount of drug required to produce an effect
Efficacy
The maximum intensity/effect/response that can be produced by a drug regardless of dose
More drug will not increase efficacy but can result in an adverse reaction
Dose response curve
Where the dose of a drug is plotted against the intensity of the effect, a curve will result
Therapeutic Index
Is a ratio of the median lethal dose (LD50) to the median effective dose (ED50)
TI = LD50 / ED50
What is a receptors function?
What the drug binds to at the cell membrane to exert its effects
Agonist
Is a drug that has affinity for a receptor, binds to the receptor, and produces as effect
Antagonist
Counteracts the action of the agonist
Three types: competitive, non competitive, physiologic
Pharmacokinetics
The study of how a drug enters the body, circulates within the body, is changed by the body, and leaves the body
What are the four major steps that influence the movement of a drug?
Absorption
Distribution
Metabolism
Excretion
Simple diffusion
Where lipid soluble substances move across the lipoprotein membrane by passive transfer
Active Transport
A process by which a substance is transported against a concentration gradient mediated by transport carriers
Facilitated diffusion
Does not move against a concentration gradient, transport via carriers
Absorption
Where drug molecules are transferred from the site of administration to the circulating blood
What factors influence the rate of absorption of a drug?
The physicochemical factors
The site of absorption
The drugs solubility
Un-Ionized means?
The uncharged portion of weak electrolytes readily crosses bodily membranes more readily because it is lipid soluble
Ionized
Weak electrolytes will pass across membranes with more difficulty because it is less lipid soluble
In the presence of infection, the acidity of the tissue ___ and the pH ___ and the effect of local anesthetics ___?
increases
Decreases
Decreases
What are the different types of absorption?
Ionization
Oral
Injection Site
Drugs that are least soluble with have the _____?
Longest duration of action
Distribution
The passage of drugs into carious body compartments such as plasma, interstitial fluids, and intracellular fluids
Redistrubution
the movement of a drug from the site of action to nonspecific sites of action
Metabolism
(aka Biotransformation) the body’s way of changing a drug so that it can be more readily excreted by the kidneys
What is the first pass effect?
When drugs that are given orally and pass through the liver prior to being circulated in systemic circulation
