NURS 3083- Pharmacology Exam 1 info

drug

ANY chemical substance that can affect living processes

-ex: supplements, vitamins, over the counter drugs (OTC), street drugs

pharmacology

the study of the preparation, uses, and effects of drugs

Clinical Pharmacology

study of drugs in humans

Pharmacotherapeutics (therapeutics)

knowing when to use drugs to prevent, diagnose, and treat

-medical use of drugs

ideal drug

-effective

-safe

-selective

effective (ideal drug)

the drug does what it's supposed to do

-the most important property a drug can have

-U.S. law requires that all drugs are proved effective before released to public

safety (ideal drug)

doesn't produce harmful effects even if it's administered in very high doses for a very long time

-all drugs can cause injury

selectiveness (ideal drug)

ONLY elicits the response for which it's given

there is no such thing as a wholly selective drug bc:

all drugs cause side effects

wish lists of ideal drug

-reversible action

-predictability

-ease of administration

reversible action

important that the effects of most drugs are reversible

predictability

knowing how the patient may/will respond

ease of administration

-simple to administer

-convenient

-#of doses per day is low

the easier a drug is to administer the:

better patient adherence and decreased risk

A baseline assessment is needed to:

evaluate both therapeutic and adverse drug response

what's the best way to reduce/avoid errors in adherence?

education

therapeutic objective of drug therapy

providing maximum benefit with minimal harm

-nurses critical responsibility

Pharmacokinetics (ADME)

the drug movement throughout the body

-absorption

-distribution

-metabolism

-excretion

absorption

movement of drug from site of administration into the blood

things that influence rate of drug absorption

1. rate of dissolving- the faster it's dissolved the faster it can get into bloodstream

2. surface area-the larger the surface area the faster the drug can get into bloodstream

3. quality of blood flow- the more blood flow to area the faster the drug can get into bloodstream

4. ability to cross membranes-lipid soluble drugs get into bloodstream fastest bc they readily cross membranes that separate them from blood

5. pH partitioning/ drug ionization- stomach is acidic 1.3, intestine is basic 6, difference in pH of plasma and the site of administration is great enough that the drugs will ionize in plasma

6. route of administration

the more drug absorbed= the _____ the effects will begin

the more drug absorbed= the ____intense the effects will be at the site of action

sooner, more

oral preparations from fastest to slowest

1. liquids, elixirs, syrups

2. suspension solutions

3. powders

4. capsules

5. tablets

6. coated tablets

7. enteric-coated tablets

different ways to administer drugs:

1. PO- oral

2. SubQ- subcutaneous

3. IM- intramuscular

4. transdermal

5. inhalation

6. IV- intravenously

Distribution

movement of drugs from blood into the interstitial space and then their target cells

3 major factors that influence effectiveness of distribution:

1. good blood flow to tissues

-specifically brain, heart, liver, kidneys

2. the ability of the drug to actually leave the vascular system and make it to target cells

3. the ability of the drug to enter the target cells

diabetic foot ulcers, abscesses, and tumors have ____ regional blood flow, therefore, affecting drug therapy

bad/low

Drugs pass _____ capillary cells rather than _____ them so movement into the interstitial space is not _____.

between, through, impeded

What drugs can cross the blood-brain barrier?

lipid soluble or have a transport system

-newborns have a immature bbb allowing for drugs to cross bbb and into CNS

placenta drug transfer

drugs are able to cross from mom to baby therefore the membranes of the placenta DO NOT cause an absolute barrier

protein binding with drugs

drugs can form reversible bonds w various proteins (albumin, glycoprotein, corticosteroid binding protein)

the % of drug molecules bound to protein is determined by:

the affinity between the protein and the drug

Albumin

most abundant plasma protein

-very large so it always stays in the blood

consequence of protein binding

restriction of drug distribution

why is it bad if a drug stays bound to a plasma protein?

then plasma drug levels increase and we cannot distribute the drug to the target cells to elicit the response

factors that determine the ability of a drug to cross cell membranes to reach their site of actions:

1. lipid solubility

2. transport system

3. presence of channels or pores

Metabolism (biotransformation)

the chemical alteration of a drug structure

-mainly occurs in the liver by p450

P450

group of 12 closely related enzyme families

6 possible consequences of therapeutic significance/drug metabolism

1. accelerated renal drug excretion

2. drug inactivation

3. increased therapeutic action

4. activation of "prodrugs"

5. increased toxicity

6. decreased toxicity

the MOST important consequence of drug metabolism:

accelerated renal drug excretion

the kidneys are unable to excrete what kind of drugs?

highly lipid-soluble drugs

-they convert them into hydrophilic forms

all _________________ are NOT excreted by the kidneys

glucuronides

-they are secreted into the bile and then transported to the duodenum and excreted in the feces

Increased therapeutic action in metabolism

metabolism can increase the effectiveness of some drugs

Decreased toxicity (metabolism)

converting drugs into inactive forms can decrease toxicity

increased toxicity (metabolism)

converting safe drugs into forms/compounds that are toxic

age affect on drug metabolism

-drug-metabolizing capacity for infants is limited

-liver isn't fully developed to metabolize drugs until 1 year

-infants are especially sensitive to drugs

-older adults metabolizing ability of drugs decreases

-drug dosages may need to be reduced in order to prevent drug toxicity

factors that decrease metabolism

-Cardiovascular dysfunction

-Renal insufficiency

-Starvation

-Obstructive jaundice

excretion

the removal of drugs from the body

how are drugs excreted by the body?

1. urine

2. bile

3. sweat

4. saliva

5. breast milk

6. expired air/exhalation

the most important organ for drug excretion:

kidneys

3 processes of renal excretion

1. glomerular filtration

2. passive tubular reabsorption

3. active tubular secretion

glomerular filtration

filtration moves drugs from blood to urine

-exception: protein-bound drugs are not filtered through bc the protein is too big

passive tubular reabsorption

drug concentrations in the blood are lower than in the tubule so the drugs want to move from the lumen of the tubule back into the blood (bc high to low)

-lipid-soluble/nonpolar drugs move back by passive reabsorption

Active tubular secretions

active transport systems in the tubules that pump drugs into the urine

2 kinds of tubular "pumps" that move drugs from blood to urine

1. organic acids

2. organic bases

age affect on excretion

-newborns kidneys aren't fully developed until a few months after birth

-infants have LIMITED capacity to excrete drugs

-old age causes renal function to decline

what must be considered when dosing or medicating infants?

they have a LIMITED capacity to excrete drugs

renal function decline with old age:

1. smaller kidneys (fewer nephrons)

2. fewer nephrons means less blood filtration

3. vascular changes with old age like atherosclerosis reduces the blood flow which results in decreased renal excretions

Non-renal routes of drug excretion

-Breast milk(lipid-soluble drugs)

-Bile(leaves body in feces)

-Lungs(anesthetics)

-Sweat and saliva(small insignificant amounts)

plasma drug levels

the amount of drug present in the blood can predict whether or not the drug is going to be therapeutic or toxic

Minimum effective concentration (MEC)

the plasma drug level below where therapeutic effects will occur

-must go higher than MEC to see therapeutic effect

Toxic Concentration (TC)

plasma drug level is too high

therapeutic range

between the MEC and TC

-where maintenance dosing is to maintain plasma drug levels

drug half life

the time it takes for 50% of a drug to decrease in the plasma/body

-50% of drug left in plasma

-drugs w shorter half-lives must be given more frequently than drugs with longer half lives

Plateau (steady state/constant serum drug level)

when a drug is administered multiple times in the same dose

-the amount of drug given=the amount of drug eliminated

usually after the ____ dose the steady state is achieved with equal doses each time

4th

when a drug is no longer administered 94% of the drug will be eliminated after how many half lives?

4

loading dose

a large initial dose given to achieve steady state faster

-give them a BIG loading dose and then smaller maintenance doses to maintain plateau

maintenance dose

small dosing used to maintain plateau

Pharmacodynamics

how the drug affects the body once at site of action

-onset

-peak

-duration

-trough

onset

The time it takes for the drug to elicit a therapeutic response

peak

The time it takes for a drug to reach its maximum therapeutic response

duration

The time a drug concentration is sufficient to elicit a therapeutic response

trough

lowest blood level

therapeutic response

the results of any medical or pharmacological treatment

-listen, respond, and act to the patient

you must have a __________________ _________________ to know if there has been a response

baseline assessment

adverse effect

undesirable and potentially harmful drug effect

adverse drug interactions

1. drugs may intensify the effects of each other

2. a drug may reduce the effect of another

3. combining drugs may produce a new response not seen with either drug alone

4. drug-food interactions

Drug-Food Interactions

-calcium-containing food and tetracycline antibiotics

-high fiber foods

-grapefruit juice effect

calcium containing food and tetracycline antibiotics

tetracycline binds to calcium and forms an insoluble/non-absorbable substance

high fiber foods can:

reduce absorption of some drugs, such as digoxin, resulting in therapeutic failure

the grapefruit juice effect on metabolism:

raises drug levels by inhibiting intestinal metabolism of the drug leads to increased absorption

Enteral routes of drug administration

goes through GI tract

-oral

-sublingual

parenteral routes of drug administration

doesn't go through GI tract

(usually by injection)

-intravenous

-subcutaneous

-intramuscular

some drugs that require parenteral routes are:

poorly water-soluble(lipid soluble)

maximal efficacy

the biggest effect a drug can produce

therapeutic index

the measure of a drug's safety (the ratio between a drug's therapeutic benefits and its toxic effects)

-narrow index is risky/unsafe

-wide index is safe

-determined by animal testing

effective dose (ED50)

the dosage required to produce a therapeutic response in 50% of the population

-the dose at the middle of the frequency distribution curve

Agonist

a drug that binds to a receptor and ACTIVATES the receptor producing a response

-can be drug or endogenous substance

Antagonist

a drug that binds to a receptor and INACTIVATES the receptor therefore no response is produced

-blocks the binding of an agonist

partial agonist (agonist/antagonist)

drug that can binds to a receptor and weakly activates the receptor not producing the max response

-moderate intrinsic activity

side effect

unavoidable secondary drug effect produced at therapeutic dose

allergic reaction

an immune response to a drug, ranging in intensity from mild itching to severe rash to anaphylaxis

in order for an allergic reaction to occur what must happen?

must be prior sensitization of the immune system

-must've already been exposed to it

-re-exposure triggers an allergic response

what measures to take when dealing with an allergic reaction?

how life-threatening the reaction was

idiosyncratic effect

an uncommon drug response resulting from a genetic predisposition

iatrogenic disease

disease caused unintentionally by medical therapy

-we cause this

-syndrome is usually identical to idiopathic diseases

idiopathic diseases

naturally occurring diseases

physical dependence (addiction)

the body has adapted to drug exposure that drug withdrawal will occur if the drug is discontinued

carcinogenic effect

drug-induced cancer

teratogenic effect

drug-induced birth defect