intro to pharm

pharmacology definition

the study of medicine

drug definition

any substance that is taken to prevent, cure, or reduce symptoms of a medical condition

drugs are a form of

medical intervention

pharmacotherapy is

the application of drugs for prevention or treatment of suffering

characteristics of an ideal drug

-Effectively treats, prevents, cures patient's condition -Produces rapid, predictable response at relatively low doses -Produces no adverse effects -Can be taken conveniently (by mouth) -Can be taken infrequently and for a short length of time -Inexpensive and easily accessible -Quickly eliminated by body after beneficial effect produced -Does not interact with other medications or food

how are drugs organized?

therapeutic classification: what is being treated by the drug AND pharmacologic classification: the mechanism of the drug or how the drug produces its effects in the body -requires understanding of biochem and physiology -may use drugs chemical name

what is a more specific classification of drugs

pharmacologic classification

chemical name of drug:

-standard nomenclature established by iupac

-each drug has only one

-clear, concise meaning of the nature of the drug

-often hard to remember/pronounce

generic drugs are less _________ than trade name drugs, but

expensive; they may differ in bioavailability (active ingredients may be same or different)

describe exclusivity in drugs

-pharmaceutical companies market their trade

-name drugs

-they claim significant difference between trade-name and generic

-consumer advocates argue generic should be available

effective pharmacotherapy depends on a nurse's

understanding of pharmacology as well as interprofessional practice

what are nursing responsibilities when it comes to drugs?

• monitoring patient's condition before and during drug use

• evaluating drug effects

• teaching patient about self-administration

• conducting medication reconciliation (making sure that we know all of the drugs a patient is taking)

what are the major goals in studying pharm?

-to eliminate med errors -to limit number and severity of adverse drug events -knowledge an ongoing lifelong process

What is the united states pharmacopeia-national forumlary?

-verifies purity and exact amounts of ingredients

-drugs marketed in the US must conform to USP-NF standards

what is the food and drug administration?

a regulatory agency responsible for ensuring that drugs and medical devices are safe and effective

what does the Center for drug evaluation and research (CDER) regulate?

drug safety

what does the center for biologics evaluation and research (CBER) regulate?

biological safety

what does the center for food safety and applied nutrition (CFSAN) oversee?

herbals, dietary supplements, cosmetics

the drug approval process established by the U.S. food and drug administration ensures

that drugs sold in the US are safe and effective

Why are meds exclusive to companies for 7 years?

because drugs are expensive to develop and release, so to make money on the drug the company needs to have exclusivity

what is off-label use?

using a drug/device for something other than its original intended use

whats an example of off label use?

Benadryl - use is antihistamine but can be used for a sleep aid or topically

prescription vs. over the counter drugs

prescription -may be addictive, may be too harmful for self-admin -treat complex conditions -require skill to administer -patient must receive authorization to receive the drug

over the counter -do not require authorization -patients may treat themselves -must carefully follow directions -no monitoring from health care provider needed

if drugs have high safety margins, they may be moved from prescription to over the counter drugs

advantages with prescription drugs

-health care provider can examine and diagnose patient -maximizes therapy -patient teaching

risks with over the counter drugs

-no drug is without risk

-patient may not choose proper meds

-no assistance from health care provider

-may be ineffective/harmful

supplements

-herbal and dietary supplements are not drugs -not subjected to same regulatory process -can cause side effects and interact w/ meds -not FDA approved

scheduled drugs

-drugs with high potential for dependence or are frequently abused

-sale and distribution are highly restricted

-placed in one of five categories called schedules

what are examples of schedule 1 drugs (highest abuse potential)

heroin, GHB. LSD, marijuana, MDMA

what are schedule 1 drugs therapeutic use?

no currently acceptable medical use; no prescriptions can be written

what are examples of schedule 2 drugs (high abuse potential)

potent opioids (codeine, fentanyl, methadone, morphine oxycodone, meperidine) as well as amphetamines, cocaine, methamphetamines, PCP, etc

what is the therapeutic use of schedule 2 drugs

have currently accepted medical use but use may be severely restricted, normally no refills are permitted

what are examples of schedule 3 drugs (moderate abuse potential)

anabolic steroids, buprenorphine katemine, codeine (lower doses compounding with aspirin or acetaminophen) and intermediate-acting barbiturates

what is the therapeutic use of schedule 3 drugs

have currently accepted medical use; less stringent controls than schedule 2 drugs, five refills allowed in 6-month period

what are examples of schedule four drugs (low abuse potential)

benzodiazepines (alprazolam, diazepam, midazolam, temazepam) long-acting barbiturates, meprobamate, pentazocine, tramadol, zolpidem

what are therapeutic uses for schedule 4 drugs

have currently accepted medical use similar controls to schedule 3 drugs 5 refills in 6 months

what are examples of schedule 5 drugs

cough meds with codeine, antidiarrheal meds with small amounts of opioids

what are therapeutic uses for schedule 5 drugs

have currently accepted medical use; similar controls to schedule 3 and 4

pharmacokinetics

study of how the organism affects the drug (what the body does to the drug)

pharmacodynamics

how a drug affects and organism (what the drug does to the body)

processes of pharmacokinetics

absorption, (how will it get in?) distribution, (where will it go?) metabolism, (how is it broken down?) excretion (how will it exit?)

absorption is the process of moving a drug from

the site of administration to the bloodstream

what is the primary factor for determining onset of drug action?

absorption

what factors affect rate and extent of drug absorption?

• dosage form

• route of administration site

• blood flow,

• GI function the presence of food or other drugs

absorption: enteral route

drugs that enter the GI tract (oral, buccal/sublingual)

Oral meds

can be tablets and capsules -must dissolve before drug is available for absorption -slow onset time -oral liquid absorbed faster

enteric coated oral meds

hard, waxy coating to resist strongly acidic stomach contents do not crush

extended release oral meds

designed to dissolve slowly for longer duration of action do not crush

sublingual/buccal routes

-meds kept in mouth -not subjected to stomach acid or first-pass effect -administer oral meds first, then sublingual meds -place buccal meds in cheek

nasogastric and gastrostomy tubes

-meds administered through devices -usually liquid form -solid drugs that are crushed tend to clog tubes -do not use sustained release meds -drugs exposed to same processes as those given by mouth

first pass effect

Drugs absorbed from the stomach and small intestine travel to liver, where they may be inactivated before reaching target organ(s)

routes that will undergo first pass?

oral (PO) gastrostomy tube (NG, OG)

topical route

applied to skin or mucous membranes local effects some given for slow release systemic effects

transdermal patches

specified amounts of medication, rate of delivery can vary

opthalamic route (eyes)

local conditions of eyes, surrounding structures

otic route (ear med)

meds should be room temperatures

intranasal route

excellent surface for drug delivery but mucus secretion unpredictable

what are other topical routes?

rectal, vaginal

parenteral route of absorption

IV, IM, intradermal and subq administration

what is the fastest onset of absorption but also the most dangerous?

IV

Intramuscular administration

drugs directly into large muscles tissue can receive larger volume of drug more rapid onset of action

intradermal and subq administration

major difference is depth of injection dermis contains more blood vessels subq route delivers drugs to deepest layers of skin (insulin, heparin)

what factors affect absorption?

GI tract environment -digestive motility differs in all patients -presence of food in stomach slows absorption -some drugs designed to be taken with or without food -high-fat meals slow -stomach motility Blood flow to absorption site -drugs absorbed faster in areas of body where blood flow is higher -such as small intestines, lungs -diminished blood flow during heart failure or shock

where does most of the absorption of meds occur in

small intestine

drug interactions types

Drug-drug and food-drug which can affect absorption

distribution

describes how drugs are transported throughout the body

how are drugs carried by blood and tissue fluids?

• action sites

• metabolism sites

• excretion sites

distribution is highly dependent on what

adequacy of blood circulation

what are barriers to distrbution?

fetal-placental barrier: protects the harmful substances passing from mothers blood stream to fetus -inefficient though, as substances like alcohol, coke, caffeine, and prescriptions can cross

Blood Brain Barrier -protects brain from pathogens and toxins

• makes it difficult for drugs to pass to brain

• lipid soluble drugs able to cross -

• not fully developed in neonates -

• inflam can increase permeability

metabolism process

changes the activity of a drug and makes it more likely to be excreted

where is the primary site of metabolism

liver

functional changes of the drug alter

pharmacological activity, so metabolites may be more toxic

what liver enzyme is responsible for metabolizing many drugs?

CYP (cytochrome P450)

CYP determines

speed at which drug is metabolized and contributes largely to drug-drug interactions

how do CYP450 inducers affect metabolism?

increase rate, breaking down more drug

how do CYP450 inhibitors affect metabolism?

decrease metabolism causing increased level of drug (ex. grapefruit juice)

excretion

• renal excretion is the primary site

• dose reduction for patients with renal impairment

• some drugs undergo reabsorption after renal filtration

pulmonary excretion

-gases and volatile liquids

-most excreted unmetabolized

-respiratory rate and blood flow affect excretion

glandular secretion

-saliva, sweat, breast milk -this is why patients can taste and smell some drugs -excretion of drugs into breast milk

fecal and billiary excretion

feces, bile: enterohepatic recirculation

-may recirculate drugs, metabolites and prolong action

therapeutic drug monitoring

results used by health care provider to keep drug does within predetermined range

minimum effective concentration

amount of drug required to produce a therapeutic effect

therapeutic range

range where the drug produces its desired action after peaking, drug plasma level fails due to excretion

toxic concentration

level of drug that results in serious adverse effects

goal of nurse

keep administered drugs within therapeutic range difference between min. effective dose and toxic dose may be narrow

drug half life

estimates the duration of action for most medications

drugs with short half life

drug given more frequently

long half life drugs

drug given less frequently

approximately how many half lives until excretion?

4

loading dose

higher amount given to "prime" blood stream

maintenance dose

keep concentration within therapeutic range

interpatient variability

patients have widely different responses to drugs the nurse needs to recognize that not all patients will experience the desired effect of a drug at the avg dose

potency

amount of drug needed to produce a specified effect

efficacy

max. response produced by a drug

Efficacy is more important than...

potency

drugs in the same class can differ in

efficacy and potency

we can't assume the drug with the lower dose will provide

fewer adverse effects

pharmacodynamics receptor interaction

most drugs produce their actions by activating or inhibiting specific cellular receptors

receptor

cellular molecule to which a med binds to produce its effects drug receptor binding is like lock and key

once the receptors are occupied,

receptors trigger second messenger -biochemical events occur -drug stimulates or inhibits activity

agonists

make the body do something -mimicking action of endogenous substances -response may be greater than endogenous activity examples - pain medication, morphine