What is Pharmacology?
scientific study of the origin, nature, chemistry, effects, and use of drugs
-how drugs work in the body
-cause & effect
Why do we need to know pharmacology?
For a safe, accurate administration of a foreign substance to a patient.
How do drugs relate to each step in the nursing process?
1. Assess = the drugs & their cause & effect
2. Diagnosis → Ex. they are having an overdose, or they are having a side effect of a drug
3. Intervention → give drugs, symptom management (nausea, pain) (ex. health promotion = vitamins)
4. Evaluation → is the drug working?
Drugs are usually referred to by what name?
Generic (aka non-propriartory name. it's the chemical name abbreviated)
What two ways are drugs classified
1. Therapeutic class = share the same use, therapy is the same, use them to treat the same thing (ex. anti hypertensives)
2. Pharmacologic class = similar characteristic anatomically, they do the same things in the body (ex. Nitrates=vasodilators)
What are the four sources of drugs?
4. synthetic = most of the drugs today
What are the five different types of plant sources for drugs?
What are alkaloid drugs?
- they are plant based
- react with acids to form salts, dissolved throughout the body
- Ex. atropine, caffeine, nicotine "-ine"
What are glycoside drugs?
- they are plant based
- occur naturally, good drug, high benefit, but toxic
- Ex. Digoxin (most common), dilantin "-in"
What is therapeutic levels?
How much, the amount, of a drug (the level) should be in the body to be therapeutic/useful/amount we want.
- can't measure all drugs, but we can measure many of the toxic drugs.
- it takes a while for toxic drugs to accumulate
What are Oil drugs?
- they are plant based
- volatile = readily evaporated or
- fixed = not readily evaporated
What types of drugs are from animal sources?
1. Hormones = insulin (pancreas/Isle of Langerhorn)
2. Oils/fats = cod liver oil
3. Enzymes = pepsin, pancreatin
4. Vaccines = flu, pneumonia
What are the different administration routes for drugs? (11)
1. Buccal (cheek), sublingual (under tongue), translingual (on tongue & allowed to dissolve)
2. Gastric = if oral is contraindicated → then directly into gastric tract (stomach) by feeding tube
3. Intradermal = into skin layer (TB, allergy)
5. Intravenous = into bloodstream via a vein (can be continuous or intermittent)
6. Oral = most common, convenient & least expensive. patient is conscious, willing & able to swallow.
7. Rectal/Vaginal = suppository, gels
8. Respiratory = gases or substances, inhaler, bronchodilaters
9. Subcutaneous = small amount of drug sub cut (fatty tissue) Ex. insulin, heparin, lenenox
10. Topical = delivered to skin or mucous membrane. difficult to evaluate & control
11. Special = epidural, intrapleural, intra-peritoneal, intra-osseous (bones), intra-articular (joints). Usually done by prescribers, not nurses
The administration route influence?
how much drug we give? how fast (rate of) absorbed, distributed & eliminated. All of this effects patient response.
How is it determined that drugs need to be removed from the market?
Based on patterns, trends & issues.
What are the four movements of pharmacokinetics
1. Absorption = taking into body & moves to the tissue
2. Distribution = movement into tissue
3. Metabolism = change into a form that can be excreted (detoxify it)
4. Excretion = removed from the body
What two ways can drugs be absorbed?
1. Passive = higher to lower concentration thru diffusion. done in order to equalize
2. Active transport = lower to higher concentration through cellular energy (ex. electrolytes are absorbed actively, most drugs absorbed actively)
What is the drug absorption rate of different drug preparation (fastest to slowest)?
1. liquids, elixirs & syrups
2. suspension solutions
6. coated tablets
7. enteric-coated tablets
What are seven factors that affect absorption?
* Rate, route, administration form
1. administration/drug form = how is it prepared & administered
2. intestinal interference = most absorbed in small intestine/GI (ex. what if part of SI is removed)
3. Liver metabolism = after absorbed→go to liver. "1st pass" to be metabolized and then sent to body.
4. Blood flow = heart must be functioning (Ex. pick w/fastest blood flow→deltoid b/c closest to the heart
5. Pain/stress= ↓ absorption (theory is ↓ blood flow to the intestine)
6. Diet = high fat diets will ↓ intestinal absorption
7. Drug combinations
What are three factors that affect distribution?
distribution = movement into tissues
1. Blood flow = ↑ flow & ↑ distribution. heart, lung, kidney disease all affect distribution
2. Solubility = water/fat soluble - fat soluble cross thru cell membranes, water soluble don't cross membrane. Also blood brain barrier & placenta
3. Protein binding = Albumin binding & 80% highly bond
How does albumin binding work?
as a drug travels it binds to albumin protein. how much gets into tissue depends on how much binds with protein. the part that binds with protein doesn't work/ineffective/doesn't get into tissue
- some drugs low protein binding & some high protein binding
What is 80% highly bond (protein)?
= high protein binding
- highly toxic & difficult to monitor, stay in the body a long time b/c bound to protein & stored in tissue
- only 20% is used, so you give more drugs which in effect makes it highly toxic
- tend to have long 1/2 life (ex. digoxin 1 dose stays in 2-3 days, better to have a short 1/2 life)
Ex. Coumadin, levothyroxine
What organs metabolize drugs?
metabolism = convert drugs into a form that can excrete.
- Liver= 80% metabolized by the liver. Might need to assess for liver function. If there is liver disease → lower dose, longer time btw, different drug. Need to MONITOR liver function
- Lungs = very small amount of metabolism
- muscle = very small amount of metabolism
What factors affect metabolism?
1. Disease = liver, heart disease (blood flow), stress, trauma
2. Genetics = quick or slow based on your genetic makeup.
3. Environment = stressful, hot or cold, smokers
4. Age = older →slows down (ex. liver function), & young (under developed livers)
How are drugs excreted from the body?
1. Kidney = main, 95%. assess kidney function = creatinine
4. Salivary glands
6. Intestinal tract
What are factors affecting 1/2 life?
- time it takes for half of the drug to leave the body
- important in regards to frequency & when to give the next dose to maintain levels of blood plasma
1. Absorption rate
(ex. digoxin 1 dose stays in 2-3 days, better to have a short 1/2 life)
- one dose generally takes 4-5 half lives for it to be out of the body & it 4-5 drugs to get a steady state
- drug takes a long time to leave if drug has long 1/2 life, so better if drug has a short 1/2 life
What is OPD?
1. Onset = time drug given until it starts its effect/work. Must consider route
2. Peak = highest concentration/effect/work. this is important for evaluation
3. Duration = low long it lasts/therapeutic effect
- OPD might be unknown for topical & enteric
What is peak & trough?
peak = concentration at the highest
trough = time for another dose
- used frequently with antibiotics. can measure in the blood how much drug is in the system
- common uses are Gentamycin & Vancomycin→both Nephrotoxic (pharmacy typically doses these drugs)
Ex. give drug & let lab know what the time drug is done & they determine when to draw the blood
= Biochemical & physical effects of drugs & the mechanism of drug action/how they work
- Drugs modify cellular function or the rate of function
What 3 ways can you modify cellular function or rate of function?
1. Agonist = interacts with receptors binds to produce effects called intrinsic activity. Initiates a response
2. Antagonsit = response prevented
a. competitive = competes w/agonist for sites
b. non-competitive = bind to sites & block effect of agonist
3. Non-selective = neither agonist or antagonist, some competitive & non-competitive. Cause widespread effects
What is drug potency?
- the amount of drug required to produce a desired response.
- compare drugs by thinking about potency. compare drugs in the same class
What is Pharmacotherapeutics?
the use of drugs to prevent and treat disease.
- drug therapy type
- the effectiveness of the drug
What is acute therapy?
critical, life threatening situations to treat a disease. Ex. heart attack → give aspirin, nitroglycerin
what is empiric therapy?
- based on practical evidence, but not scientific data/evidence. Used before & seemed to help.
Ex. bronchitis antibiotic even though not bacterial but makes patient better
what is maintenance therapy?
- chronic conditions that will never resolve.
Ex. hypertension, COPD, insulin
What is supplemental/replacement therapy?
- don't have what you need so you replace.
Ex. thyroid, estrogen, insulin, vitamins
What is supportive therapy?
Doesn't treat the disease but maintains the body system until the condition resolves.
Ex. Lung cancer → antibiotic for pneumonia is supporting the respiratory system
What is palliative therapy?
- comfort therapy for terminal diseases or EOL care
Ex. Morphine for pain
What are the factors affecting drug response?
1. Age = ↓ metabolism, blood flow & liver in young & old
2. Diet = ↑ in fat may alter
3. Dx's = heart disease → ↓ blood flow, kidney =↓ excretion
4. Other meds = drug interactions (polypharmacy)
5. Gender infection = b/c of hormones. Infections can effect→causes stress, processes speeded up. might affect efficacy & ↓ effectiveness
6. CV/Renal/Hepatic function
What can effect drug tolerance?
- patient has a ↓ response to a drug over time. need higher dose of drugs to get the effect you want. Ex. drugs for nausea
- can only give so much (dose) so may have to do something different. Already at dose limit
What is drug dependence & the two types?
- a patient displays a physical or psychological need for a drug
physical=symptoms when you don't get the drug. withdrawal
psychological=emotional response that you need the drug for comfort or well being
What is additive drug interaction?
2 drugs with with similar actions, give together to maximize effect so we can give lower doses of drugs
What is potentiation drug interaction?
2 drugs, 1 drug makes the other drug stronger (potentiates the drug) so we get a better effect
What is antagonistic drug interaction?
2 drugs, response is less than either alone. they work against each other for a lessor response
↑ or ↓ absorption drug interaction?
intestine/stomach - 1 drug uses all HCI so the 2nd drug can't be absorbed
What is an adverse drug reaction/side effect?
- a harmful undesirable response
- mild → severe
Severity may depend on dose. May be patient dependent (young & old)
What is the dose related reaction of secondary effects?
- drug that has another effect than its intended effect. Ex. morphine is given for pain, 2° effect is ↓ respirations
- you may give the drug for 2° effect
What is the dose related reaction of hyper susceptibility?
- even with a normal dose the patient responds highly with effects. Ex. Cumadin → patient will just start bleeding
what is the dose related reaction of overdose?
- intentional or accidental. most susceptible are young, old, heart/kidney/lung/liver disease
what is the dose related reaction of iatrogenic effect?
- mimics a disorder
Ex. aspirin causing GI disturbance/GI bleed
What are some patient sensitive adverse reactions?
1. Less common
a. drug allergy = immune system is trying to neutralize or destroy the drug. Can be mild or anaphylactic
b. Idiosyncratic = caused from unknown reason → genetic reason. unknown hypersensitivity