Chapter 2 Flashcards by Z Q

absorption

what happens to a drug from the time it enters the body until it enters the circulating fluid. IV administration causes the drug to directly enter the circulating blood, bypassing the many complications from other routes

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active transport

the movement of substances across the cell membrane against the concentration gradient; this process requires the use of energy

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Chemotherapeutic agents

Synthetic chemicals used to interfere with the functioning of foreign cell populations, causing cell death.

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Critical concentration

the concentration a drug must reach in the tissues to cause the therapeutic desired effect

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Distribution

movement of a drug to body tissues; places where the drug may be distributed

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enzyme induction

A chemical that is transformed by an enzyme system in the liver = causes increased activity of the enzyme system

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excretion

removal of a drug from the body; particularly occurs in the kidneys, but can also occur through the skin, lungs, bile or feces

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first-pass effect

drugs are given orally -go to liver where they can be largely inactivated by liver enzymes before they can enter general circulation

*oral drugs are frequently given in higher doses due to this breakdown

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glomerular filtration

the passage of water and water-soluble components from the plasma to the renal tubule

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Half-life

The time it takes for the amount of drug in the body to decrease to one-half of the peak level it previously achieved

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Hepatic microsomal system

liver enzymes tightly packed together in the hepatic intracellular structure, responsible for the biotransformation of chemicals

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loading dose

the use of a higher dose then what is usually used for treatment to allow the drug to reach critical concentration sooner

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Passive diffusion

movement of substsances across a semipermeable membrane with a concentration gradient; does not require energy

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Pharmacodynamics

Study of interactions between the chemicals of living systems and foreign chemicals, that enter living organisms.

*the way a drug effects the body

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pharmacogenetics

the study of genetically determined variations in response to drugs

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Pharmacokinetics

the way the body deals with a drug
including absorption, distribution, biotransformation, and excretion

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placebo effect

documented effect of the mind on drug therapy

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receptor sites

specific areas on cell membranes that react with certain chemicals to cause an effect within the cell

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Selective toxicity

Property of a chemotherapeutic agent that effects only systems found in forgein cells, without affecting healthy human cells

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Drugs usually work in 1 of 4 ways?

to replace or act as subs for missing chemicals
to increase or stimulate certain cellular activities
To depress or slow certain cellular activities
to interfere with the functioning of foreign cells

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The interaction between a chemical and receptor of a site affects enzyme systems within the cell. The affected enzymes then produce certain effects such as,

increased or decreased cellular activity, changes in cell membrane permeability, or alterations in cellular metabolism

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Agonist

drugs that interact directly with receptor sites to cause the same activity as natural chemicals

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Antagonist

binds to receptor site and blocks drug from binding

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Competetive antagonist

binds to different receptor sites but still prevents drug from binding

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noncompetetive antagonist

can prevent the action of an agonist without any effect on the binding of the agonist to the receptor.

What is a drug that has selective toxicity?

Penicillin

Pharmacokinetic considerations include

onset of drug action (time to effects) drug half life timing of the peak effect duration of drug effects metabolism of drug effects site of excretion

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Tissue - site of action (therapeutic, toxic) Tissue - storage sites (fat or protein)

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Reabsorption Excretion by: kidney, bile, lungs, etc Reabsorption

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Biotransformation in : Liver, kidneys, plasma, etc

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Drug dose administered to Gi tract, muscle, subcutaneous tissue

What 2 drugs in the book are started with a loading dose?

Digoxin & xanthine bronchodialator

Dynamic equilibrium involves the rate of several processes

absorption from the site of entry distribution to the active site biotransformation in the liver excretion from the body ** key elements in determining amount and frequency of drug

What are the areas drugs can be absorbed

Rectally or orally to GI tract through mucus membranes through skin through lungs Muscle or subcuteanous tissue

ROUTE: Intravenous FACTORS AFFECTING ABSORPTION:

FACTORS AFFECTING ABSORPTION: none, direct entry to circulatory system

ROUTE: Intramusclular FACTORS AFFECTING ABSORPTION:

Perfusion or blood flow to the muscle fat content of muscle Temp of muscle

ROUTE: Subcutaneous FACTORS AFFECTING ABSORPTION:

Blood flow to tissue Fat content temp

ROUTE: PO oral FACTORS AFFECTING ABSORPTION:

Acidity of stomach length of time in stomach blood flow to GI tract presence of interacting foods or drugs

ROUTE: PR rectal FACTORS AFFECTING ABSORPTION:

Blood flow to rectum lesions in rectum length of time retained for absorption

ROUTE: Mucous membranes (buccal or sublingual) FACTORS AFFECTING ABSORPTION:

Blood flow to area integrity of membranes Presence of food or smoking length of time in area

ROUTE: Topical (skin) FACTORS AFFECTING ABSORPTION:

Blood flow to area integrity of skin

ROUTE: Inhalation FACTORS AFFECTING ABSORPTION:

Blood flow to the area integrity of lung lining ability to administer drug properly

Drugs can be absorbed through the cells through what processes

Passive diffusion Active transport Filtration

Passive diffusion occurs quickly if

drug molecule is small soluable in water and lipids has no electrical charge

What are factors that can affect distrubiton?

drugs lipid soluability & ionization perfusion at site

Most drugs are bound to protien in the blood, the more bound the

the more difficult it can be for the medication to be released. The drug must be freed to act on tissues Tightly bound = longer duration loosely bound - shorter duration

Some drugs compete for protien binding sites which can cause

Altering effectiveness or causing toxicity

Blood brain barrier

Protective system of cellular activity that keeps many things away from the CNS

Drugs that are _____soluable are more likely to pass the BBB into the CNS

highly lipid soluable **Important in treating brain infections with antibiotics//can only treat when infection is so severe it alters BBB

What organ is the most important site of drug metabolism?

the liver **the liver detoxifies many chemicals and uses others to produce enzymes and structures

Drugs that are taken orally are usually absorbed from ----- to ----

from small intestine to portal venous system

What is the first pass effect?

a large % of the oral dose is destroyed and never reaches the tissues **recommended dose of oral drug is usually higher due to this an other forms of the drug

Phase I biotransformation involves oxidation, reduction or hydrolysis of the drug via

cytochrome P450 system of enzymes ***abundant in liver

Drugs that increase cytochromse P450 system enzymes

Nicotine Alcohol glucocorticoid

Drugs that decrease cytochrome P450 system enzymes

ketoconazole Amiodarone Quinidine

Drugs that have been made water soluable in the liver are often readily excreted from ---- by ---

Kidneys by glomerular filtration

What 2 things should you consider before administering a drug?

patients kidney function, liver function and urine acidity

If the liver is not functioning properly what can happen to the drug

may not be metabolized correctly and may be toxic

If the kidneys is not functioning properly what can happen to the drug

drug may not be excreted properly and may accumulate in body

What are factors that affect the bodys response to a drug

Weight, age, gender, physiological factors (hydration, acid/base), pathological factors (disease), genetic, immunological (allergies), psychological, environment, drug tolerance, interactions

Recommended drug does are based on drug eval studies and on ---LB person

150lbs

What is the fried rule for pediatric doses

(1-2 years) = age in months _________________ 150 X AVG adult does

What is the young rule for pediatric doses

(1-12 years) = Childs age/ childs age+12 X avg adult dose

What is the clark rule for pediatric doses

LB of child/150 X avg adult dose

What is the surface area rule for pediatric doses

surface area of child sq m/1.73 X avg adult dose

The goal of establishing dosing schedules is

to achieve critical concentration in the body