Adam Pharmacology For Nurses Ch 4 Pharmacokinetics Unit1Core Concepts (Elisa)

Front 1

How do we define the term Pharmocokinetics?

Back 1

-the study of drug movement throughout the body.
(slide 3,4)

Front 2

Why is Pharmocokinetics Important? (three things)

Back 2

-Important to know how the body handles medication
-Understand actions and side effects of drugs
-Understand obstacles drug faces to reach target cells
(slide4)

Front 3

What are 4 obstacles Drugs face in the Body?

Back 3

-Greatest barrier for many drugs is crossing many membranes
-Enteral route drugs broken down by stomach acids and enzymes
-Organs attempt to excrete medicines
-Phagocytes may attempt to remove medicines seen as foreign (slide 5)

Front 4

What are the four processes of Pharmocokinetics?

Back 4

-Absorption
-Distribution
-Metabolism
-Excretion
(slide 6,7 )

Front 5

Define Absorption

Back 5

-Movement from site of administration, across body membranes, to circulating fluids (slide9 )

Front 6

What is the Primary factor determining length of time for effect of drug to occur?

Back 6

Absorption
(slide 9 )

Front 7

How do Drugs Cross Plasma Membranes to Produce Effects?

Back 7

-Diffusion or passive transport
-Active transport
(slide 10 )

Front 8

When thinking about Passage of Drugs through membranes
What is Active transport?

Back 8

– chemical move against a concentration or electrochemical gradient
(slide 11)

Front 9

When thinking about Passage of Drugs through membranes
What is Co-transport?

Back 9

-involves the movement of two or more chemicals moving across a membrane
(slide 11)

Front 10

When thinking about Passage of Drugs through membranes
What is Diffusion or passive transport ?

Back 10

– this is movement of a chemical from an area of higher concentration to an area of lower concentration.
(slide 11)

Front 11

Does the Routes of drug administration effect absorption?

Back 11

YES
 Enteral
 Oral - tablets, capsules or liquid
 Nasogastric or GI tubes
 Sublingual
 Buccal
 Parenteral
 IV
 IM
 Subcutaneous or
 Intradermal
 Topical
 Ophthalmic
 Vaginal
 Nasal
 Rectal suppositories
 Transdermal
 Otic
 Inhalers
(slide 12)

Front 12

What factors might inhibit drugs from being absorbed or slow the process of absorption? Name at least 6

Back 12

-Factors Affecting Drug Absorption
-Route of administration
-Drug formulation
-Drug dosage
-Digestive motility
-Digestive tract enzymes
-Blood flow at administration site
-Degree of ionization of drug
---In acid of stomach, aspirin is non-ionized and easily absorbed by bloodstream
---In alkaline of small intestine, aspirin is ionized and less likely to be absorbed
-pH of surrounding environment
-Drug-drug/drug-food interactions
-Dietary supplement/herbal product–drug interactions (slide 13,14,15)

Front 13

What is the Effect of pH on drug absorption(acid and base)?

Back 13

-(a) a weak acid such as aspirin (ASA) is in a nonionized form in the acidic environment and absorption occurs;
-(b) in a basic environment, aspirin is mostly in an ionized form and the absorption is prevented. (Slide 16,page 39 Figure 4.2)

Front 14

After Absorption where does the drug go?

Back 14

- to the kidney for elimination
- Or to the tissues and receptors then into blood stream
(slide 17)

Front 15

What do we mean by the term “first-pass effect”?

Back 15

-Drugs are absorbed across the intestinal wall and enter the hepatic portal circulation
(slide 18,19)

Front 16

What route would Drugs Enter Hepatic-Portal Circulation (First-Pass Effect)?

Back 16

Oral (slide 20)

Front 17

What is Hepatic-Portal Circulation?

Back 17

After drug is absorbed it moves From the small intestine directly to the liver via hepatic portal circulation, then on to the liver (page 40)

Front 18

Define conjugates during metabolism.

Back 18

-During metabolism the addition of side chains is known as conjugates.
-makes drug more water soluble and more easily excreted by the kidneys.

Front 19

Describe Hepatic-Portal Circulation (First-Pass Effect) (what are the steps involved)?

Back 19

-Drug absorbed
-Drug enters hepatic circulation, goes to liver
-Drug is metabolized to inactive form
-Drug conjugates and leaves liver
-Drug is distributed to general circulation
(slide 20)

Front 20

Why might the first pass effect be a problem for drugs?

Back 20

Many drugs rendered inactive by first-pass effect
(slide 20)

Front 21

What type of drugs would avoid the first pass effect
(think routes)?

Back 21

-drugs that by pass the GI system via parenteral route such as IV, IM, or subcutaneous
(slide 21),22

Front 22

What three factors may affect drug distribution in the circulatory system?

Back 22

-Protein binding
-Lipid solubility
-Circulation
(slide 23,24)

Front 23

What is Distribution?

Back 23

– transport of the drug via blood
(slide 25)

Front 24

How does Protein binding affect drug distribution?

Back 24

--May not leave much drug available, but some drugs depend on it!
(slide 25)

Front 25

How does Lipid solubility affect drug distribution?

Back 25

--move easily through the cell membrane
(slide 25)

Front 26

How does Circulation affect drug distribution?

Back 26

--Blood volume
---Vascular resistance
---Cardiac output
(slide 25)

Front 27

Define Vascular resistance

Back 27

-refers to the resistance to blood flow offered by all of the systemic vasculature, excluding the pulmonary vasculature. (slide 25)

Front 28

Define Cardiac output

Back 28

– volume of blood pumped by the heart during one minute
(slide 25)

Front 29

What does Distribution involve?

Back 29

-the transport of pharmacologic agents throughout the body
(slide 26)

Front 30

What is the Simplest factor determining distribution?

Back 30

the amount of blood flow to body tissues
(slide 26)

Front 31

What has a big influence in distribution of a drug?

Back 31

-Physical properties of drug
(slide 26)

Front 32

Define affinity

Back 32

-attraction, for certain medications
(slide 26)

Front 33

What may have a have a high affinity, or attraction, for certain medications?

Back 33

Certain tissues, such as bone marrow, teeth, eyes, adipose tissue.
(slide 26)

Front 34

What are factors that may affect Distribution of Medications?

Back 34

-Drugs and other chemicals compete for plasma protein–binding sites
-Drug–drug and drug–food interactions may occur when one drug displaces another from plasma proteins
-Some have greater affinity
-Displaced drug can reach high levels
-Can produce adverse effects
(slide 27)

Front 35

How are Enteral drugs distributed?

Back 35

-they are broken down by digestion system to be used or distributed to the body
(slide 28)

Front 36

How are Parenteral drugs distributed?

Back 36

-drugs enter through the blood stream by absorption
(slide 28)

Front 37

In reference to Distribution of Medications what is important about the Blood-brain barrier and fetal-placenta barrier?

Back 37

-They are special anatomic barriers that prevent many chemicals and medications from entering
-Makes brain tumors difficult to treat
-Fetal-placenta barrier protects fetus; no pregnant woman should be given medication without strong consideration of condition
(slide 29)

Front 38

What are the issues with Drugs that Bind with Plasma Proteins?

Back 38

-Many drug molecules form drug–protein complexes – binding reversibly to plasma proteins – and thus never reach target cells
-Cannot cross capillary membranes
-Drug not distributed to body tissues
(slide 30)

Front 39

Describe Plasma protein binding and drug availability

Back 39

(a) drug exists in a free state or bound to plasma protein;
(b) drug-protein complexes are too large to cross membranes.
(Slide 31 page 39 Figure 4.3)

Front 40

Describe Enterohepatic Recirculation
of Drugs (2 steps and 3 important factors to consider)

Back 40

-Drugs excreted in bile (to small intestine)
-Bile recirculates to liver (via hepatic portal circulation)
-Percentage of drug re-circulated numerous times (Enterohepatic Recirculation
of drugs)
-Prolongs activity of drug
-Activity of drug may last after discontinuation
(Slide 32,33 page 42 Figure 4.5 Enterohepatic recirculation)

Front 41

What are some factors that effect metabolism of medications and Pharmacotherapy?

Back 41

-Can be decreased metabolic activity in some clients
-Infants and elderly
-Clients with severe liver disease
-Clients with certain genetic disorders
-Dosages need to be adjusted in these clients
(slide 35)

Front 42

What are three Drug plasma concentrations related to the therapeutic response?

Back 42

-Minimum effect concentration
-Toxic concentration
-Therapeutic range
(slide 36)

Front 43

Why do we measure Drug Plasma Concentration to measure therapeutic response?

Back 43

Concentration of medication in target tissue often impossible to measure, so must be measured in plasma (slide 37)

Front 44

What is Minimum effective concentration

Back 44

- amount of drug required to produce a therapeutic effect (slide 37)

Front 45

What is Toxic concentration

Back 45

- level of drug that will result in serious adverse effects (slide 37)

Front 46

What is Therapeutic range

Back 46

- plasma drug concentration between the minimum effective concentration and the toxic concentration
(slide 37)

Front 47

Define Plasma Half-Life (t1/2) of Drugs

Back 47

-Length of time needed to decrease drug plasma concentration by one half (slide 38)

Front 48

Why is Plasma Half-Life (t1/2) of Drugs important to know?(give 2 reasons)

Back 48

-The greater the half-life, the longer it takes to excrete
-Determines frequency and dosages we use
(slide 38)

Front 49

How do Drug Reaches and Maintains Therapeutic Range? (4 components)

Back 49

-Repeated doses of drug given
-Drug accumulates in bloodstream
-Plateau reached
-Amount administered equals amount eliminated
(slide 39)

Front 50

What is onset of action?

Back 50

-When drug reaches beginning of therapeutic range
(slide 40, Figure 4.6, page 43)

Front 51

What is duration of action?

Back 51

-Time the drug is with-in the therapeutic range.(termination – onset) (slide 40, Figure 4.6, page 43)

Front 52

What is termination of action?

Back 52

-The point when the drug is dropping below the therapeutic range. (slide 40, Figure 4.6, page 43)

Front 53

What is peak plasma concentration?

Back 53

-Highest concentration of drug just before concentrations starts to decline. (slide 40, Figure 4.6, page 43)

Front 54

Define Bolus

Back 54

-Loading Dose
-Higher amount of drug given
(slide 41)

Front 55

What is the reason for giving a bolus?

Back 55

Plateau reached faster
Quickly produces therapeutic response
(slide 41)

Front 56

What is a Maintenance Dose?

Back 56

-Keeps plasma-drug concentration in therapeutic range

Front 57

What are Receptors in the body?

Back 57

-Receptors signal the cells to do something
--For example:
---make a hormone (insulin)
---decrease the blood pressure
-----Drugs can be agonists or antagonists
(slide 44)

Front 58

What is an Agonists drugs?

Back 58

-helps to produce the desired effect
-Agonist -Bind to receptors and produce a therapeutic effect
--Example: Urecholine – binds with acetylcholine receptors and produces the same actions as acetylcholine allowing for increase in the tone of urinary muscles assisting with urination
(slide 46,47)

Front 59

What is an Antagonist drug?

Back 59

-stop or block the actions of something to produce a desirable effect
-Antagonist -Bind to the receptor and block its actions preventing the cells from doing something
--Example – antihypertensive medication
---atenolol - Stop BP from increasing
(slide 46,48)

Front 60

What is another name for Metabolism?

Back 60

-Biotransformation
(slide 49)

Front 61

What are four components of Biotransformation?

Back 61

-Changes drug so it can be excreted
-Involves biochemical reactions
-Liver—primary site
-Addition of side chains, known as conjugates, makes drugs more water soluble and more easily excreted by the kidneys
(slide 49)

Front 62

What is the Hepatic microsomal enzyme system (P-450 system), and what does it do?

Back 62

-Metabolism in the Liver
-Inactivates drug
-Accelerates drug excretion
-Some agents, known as prodrugs, have no pharmacologic activity unless first metabolized to active form by body
---(benazepril) Lotensin or losartan (Cozaar)
(slide 50)

Front 63

What is the primary Excretion site?

Back 63

the kidneys
(slide 51)

Front 64

What is important to know about the patients kidney function when administering certain drugs?

Back 64

-May not be a big deal until you have a patient with kidney disease
--pts can’t process the drug
--allows build up in the body
(slide 51)

Front 65

What happens in the Primary Site of Excretion of Drugs known as the Kidneys?

Back 65

-Free drugs, water-soluble agents, electrolytes, and small molecules are filtered
-Drug-protein complexes are secreted into distal tubule
(slide 52)

Front 66

What is important to know about the Kidneys Secretion mechanism in infants and older adults?

Back 66

It is less active.
(slide 52)

Front 67

What can increase excretion from the kidneys?

Back 67

pH of filtrate
(slide 52)

Front 68

What three Other Organs Can Be Sites of Excretion?

Back 68

-Respiratory system
-Glands
-Biliary system
(slide 53)

Front 69

How does Renal Failure affect/Diminishes Excretion of Medications?

Back 69

-Drugs retained for extended times
-Dosages must be reduced
(slide 54)

Front 70

Name two ways we might compare drugs/meds?

Back 70

-Potency
-Efficacy
(slide 54)

Front 71

What is Potency?

Back 71

-Drug with higher potency produces a therapeutic effect at a lower dose, compared with another drug in the same class
(slide 57)

Front 72

What is Efficacy?

Back 72

-Efficacy – ability of drug to produce the desired response
--How efficient is the drug being metabolized in the body with that particular patient?
(slide 57)

Front 73

What are some important considerations prior to drug administration that may modify drug response? (Name 5 of 10)

Back 73

-Age – infants and elderly are more sensitive
-Body weight – obese or very thin may need dose adjustments
-Toxicity – adverse symptoms
-harmacogenetics – genetic influences
-Time of administration – food in stomach
-Emotional factors – depression may not take (refuse to take) meds
-Pre-existing disease states – effect liver, kidney, heart, circulatory system
-Tolerance – can increase over time
-Cumulative effect – metabolized slower and excreted more slowly than rate of administration
-Drug-drug interactions – effects of combination of drugs, may compete for same receptor sites. Adverse reaction may lead to toxicity or complications or anaphylaxis
(slide 59)

Front 74

What are four Skill of Nurse Critical In Determining If Average Dose Is Effective?

Back 74

-Client observation
-Taking of vital signs
-Monitoring lab data
(slide 61)

Front 75

What is the liability of the nurse once the medication has been administered?

Back 75

-Once the medication has been administered, the nurse becomes liable for the predicted effects of that drug! (slide 61)