Pharmacology Ch. 4-5

Front 1

What is the meaning of pharmacokinetics?

Back 1

The sutyd of drug movement throughout the body. It describes how the body deals with medications.

Front 2

What is the greates barrier drugs face in reaching their target cells?

Back 2

Crossing membranes

Front 3

What are the four categories of pharmacokinetics (processes)?

Back 3

1. absorption
2. distribution
3. metabolism
4. excretion

Front 4

What 2 ways do drugs cross body membranes?

Back 4

1. Active transport (against concentration/electrochemical gradient)
2. Diffusion/passive transport

Front 5

What is absorption?

Back 5

A process involving the movement of a substance from its site of administration, across body membranes, to circulating fluids.

Front 6

Which is faster in regard to absorption--IM administration or IV administration? Why?

Back 6

IV administration because it enters the bloodstream directly.

Front 7

What factors affect aborption?

Back 7

Dose of medication
Speed of digestion
Exposure to enzymes (GI)
Blood flow to site of admin.
Degree of ionization (pH)
Drug/Drug and Food/Drug interactions

Front 8

In a basic environment, aspirin is mostly in what form? What happens to the absorption?

Back 8

Ionized form
In this case, absorption is prevented.

Front 9

Is aspirin an acidic or a basic substance?

Back 9

Aspirin (ASA) is a weak acid

Front 10

What is affinity in regard to pharmacokinetics?

Back 10

Affinity is the attraction that tissues have for certain medications.

Front 11

Only (bound/unbound) drugs can reach their targe cells or be excreted by the kidneys.

Back 11

Unbound (free) drugs

Front 12

Give examples of two spcial anatomic barriers that prevent many chemicals and medications from entering.

Back 12

Blood-brain barrier
Fetal-plancental barriers

Front 13

List some medications that are readily able to cross the blood-brain barrier and produce actions in the CNS.

Back 13

sedatives
anti-anxiety agents
anticonvulsants

Front 14

List some substances that easily cross the plancental barrier and can potentially harm the fetus.

Back 14

alcohol
cocain
caffeine
certain Rx meds

Front 15

What is another name for metabolism in regard to medications?

Back 15

biotransformation

Front 16

What is the hepatic microsomal enzyme system?

Back 16

The enzyme complex (P-450 system) which inactivates drugs and acclerates their excretion.

Front 17

What is the "first-pass" effect?

Back 17

This is when drugs absorbed after oral administration cross directly into the hepatic portal circulation, which carries blood to the liver before it is distributed to other body tissues (therefore, some drugs can be completely metabolized to an inactive form before reaching the general circulation)

Front 18

List the steps of the first-pass effect

Back 18

1. drugs are abbsorbed
2. drugs enter the hepatic portal circultion and go driectly to the liver forming...
3. drug conjugates, leaving liver
4. drug is distributed in the general circulation

Front 19

What are conjugates?

Back 19

Side chains added to drugs during metabolism to make them more water soluble and easily excreted by the kidneys.

Front 20

What are prodrugs?

Back 20

Agents that have no pharmacologic activity unless first metabolized to their active form by the body
ie: benazepril (Lorensin)
losartan (Cozaar)

Front 21

What is enzyme induction?

Back 21

The process that increases metabolic activity in the liver, which may require higher doses of meds to achieve the optimum therapeutic effect.

(ie: phenobarbital causes the liver to synthesize more microsomal enzymes, therefore increases the rate of its own metabolism.)

Front 22

What is excretion?

Back 22

Drugs being removed from the body.

Front 23

What is the primary site of excretion?

Back 23

Kidneys

Front 24

What is the kidney filtration rate in an average-size person?

Back 24

180 L of blood each day

Front 25

What substances are filtered at the glomerulus?

Back 25

Free drugs
Water-soluble agents
Electrolytes
Small molecules

Front 26

What substances are not filtered due to large size?

Back 26

Proteins
Blood cells
Conjugates
Drug-protein complexes

Front 27

Patients with renal failure will have (diminished/enhanced) ability to excrete medications

Back 27

Diminished, therefore they may retain drugs for an extended period of time.

Front 28

The rate of respiratory excretion is dependent on factors that affect gas exchange. List those factors.

Back 28

Diffusion
Gas solubility
Pulmonary blood flow

Front 29

What is the relationship between breathing rate/blood flow to lungs and excretion?

Back 29

The faster the breathing rate, the greater the excretion;
The greater the blood flow into lung capillaries, the greater the excretion.

Front 30

Where are water-soluble drugs secreted?

Back 30

Saliva
Sweat
Breast milk

Front 31

Explain why some patients experience an "odd" taste when given IV drugs

Back 31

This is attributed to the secretion of agents into the saliva

Front 32

Why should nursing mothers always check with their provider before taking any Rx, OTC drugs, or herbal supplements?

Back 32

Because these agents can be secreted into breast milk, thus becoming an exposure risk to the infant.

Front 33

What is the minimum effective concentration?

Back 33

The amount of drug required to produce a therapeutic effect

Front 34

What is the toxic concentration?

Back 34

The level of drug that will result in serious adverse effects

Front 35

The plasma concentration between the minimum effective concentration and the toxic concentration is called the what?

Back 35

Therapeutic range

Front 36

Define plasma half-life

Back 36

The length of time required for the plasma concentration of a medication to decrease by one-half after administration (can be a few minutes to hours or days)

Front 37

What is the relationship between half-life and excretion?

Back 37

The greater the half-life, the longer it takes a medication to be excreted.
ie: A drug with t 1/2 of 10 hours would take longer to be excreted than a drug with t 1/2 of 5 hours.

Front 38

Given the following:
t 1/2 = 14 hours
t 1/2 = 2 days
Which medication would produce an effect that would last longer in the body?

Back 38

The drug with the t 1/2 of 2 days (longer half-life = longer duration, longer effect, takes longer to be excreted)

Front 39

Drugs with relatively short half-lifes (ie: aspirin t 1/2 =15-20 min) need to be given how often? What about drugs with longer half-lifes (ie: Plendil t 1/2 = 10 hours)?

Back 39

Aspirin--every 3-4 hours
felodipine (Plendil)==once/day

Front 40

If a patient has extensie renal or hepatic disease, the plasma half-life of a drug will (increase/decrease). Explain.

Back 40

Increase. The drug concentration may reach toxic levels, therefore dosages must be reduced and meds given less frequently.

Front 41

How long does it take (theoretically) to reach even distribution of continuous therapeutic level of drug to body tissues (equilibrium)?

Back 41

4 half-lives

Front 42

What is a loading dose?
Maintenance dose?

Back 42

Loading--higher amount of drug, often given only once or twice to "prime" the bloodstream with a sufficient level of drug
Maintenance--given to keep the plasma drug concentration in the therapeutic range.

Front 43

Using a routing dosing schedule with antibiotics, how long does it take to reach therapeutic level?

Back 43

Almost 5 doses (48 hours)

Front 44

How long does it take to reach therapeutic level when using a loading dose of antibiotics?

Back 44

Level is reached within 12 hours

Front 45

What can frequency distribution curves show?

Back 45

1. The number of patients responding to a drug action at different doses
2. Represents the safety of a drug (think median lethal dose)

Front 46

Give the equation for Therapeutic Index

Back 46

TI = median lethal dose divided by median effective dose

Front 47

What is the meaning of therapeutic index?

Back 47

It is a measure of the drug's safety margin: The higher the therapeutic index, the safer the medication

Front 48

How is the median toxicity dose calculated?

Back 48

TD50 is the dose that will produce a given toxicity in 50% of a group of patients.

Front 49

How is median lethal dose calculated?

Back 49

The LD50 cannot be experimentally determined in humans, so it is tested on animals during the phase trials.

Front 50

What is the relationship between the two components of the equation for therapeutic index?

Back 50

The larger the difference between the two doses, the greater the therapeutic index, thus the safer the medicine.

Front 51

Explain potency

Back 51

A drug that is more potent will produce a therapeutic effect at a lower dose, compared with another drug in the same class.

Front 52

Explain efficacy

Back 52

The magnitude of maximal response that can be produced from a particular drug.

Front 53

Which is more important? Potency or efficacy?

Back 53

Efficacy is almost always more important than potency, from a pharmacotherapeutic perspective.

Front 54

How do drugs act?

Back 54

By modulating or changing existing physiologic and biochemical processes.

Front 55

What is a receptor?

Back 55

The cellular macromolecule to which a medication binds in order to initiate its effects

Front 56

Explain the receptor theory

Back 56

A drug binds to a receptor to cause a change in body chemistry or physiology. These receptors do not exist in the body solely to bind drugs. Their normal function is to bind endogenous molecules (hormones, nerotransmitters, growth factors)

Front 57

What type of substance are the majority of macromolecules?

Back 57

Proteins

Front 58

Once a drug binds to the receptor, what happens?

Back 58

A series of second messenger events within the cell may be triggered (ie: conversion of adenosine triphosphate--ATP--to cyclic-AMP) and biochemcial cascades initiate the drug's action by either stimulating or inhibiting normal activity of the cell.

Front 59

How many basic receptor types exist?

Back 59

Two--alpha and beta
Both have subtypes (alpha 1&2, and beta 1&2)

Front 60

A drug that produces the same type of response as the endogenous substance is known as

Back 60

an agonist

Front 61

What is an antagonist?

Back 61

A drug that occupies a receptor and prevents the endogenous chemical from acting.

Front 62

Is atropine an agonist or an antagonist?

Back 62

An antagonist--it inhibits the effects of acetylcholine by competing for the binding sites

Front 63

Is competitive inhibition the only way antagonists work? Explain.

Back 63

No. Functional antagonists inhibit the effects of an agonist not by competing for a receptor but by changing the pharmacokinetic factors (slowing absorption, speeding up metabolism or excretion, etc.)

Front 64

Males of Mediterranean and African descent are more likely to express a deficiency in the enzyme glucose-6phosphate dehydrogenase (G6PD). What does this result in?

Back 64

In administering certain drugs (ie: primaquine, sulfonamides, nitrofurantoin) an acute hemolysis of red blood cells occurs and up to 50% of the circulating RBCs may be destroyed. Nurses must observe patients carefully following the admin of these meds. Their are alternative medications.

Front 65

What are idiosyncratic reactions?

Back 65

Unpredictable and unexplained drug reactions

Front 66

What is a drug that occupies a receptor site and prevents endogenous chemicals from acting?

Back 66

An antagonist

Front 67

Morphine has a greater efficacy than either of the OTC drugs aspirin or acetaminophen. Based on what a nurse knows about efficacy, what patient condition might require a dose of morphine rather than aspirin or acetaminophen?

Back 67

A patient in moderate to severe pain after the otehr drugs have been ineffective for pain relief

Front 68

You read that the drug to be given to a patient has a "narrow therapeutic index", this means

Back 68

The drug has a narrow safety margin and even a small increase in dose may produce adverse or toxic effects.