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What is Pharmacotherapeutics?
The use of drugs to diagnose, prevent, or treat disease or to prevent pregnancy
The medical use of drugs
What is Affinity?
The strength of the bond between the drug and its receptor
What is antagonism?
The opposition between 2 or more medications
for example, opioids and narcan
What is a bolus?
- A single, often large dose of a drug.
- Often given as an initial dose
What is cumulative action?
- An increased effected caused by multiple doses of the same drug
- Caused by a buildup in the blood
What is efficacy?
The degree to which a drug is able to induce maximum effects
ex. Drug AA reduces BP by 20mm while Drug BB reduces BP by 10mm. Drug AA has a greater efficacy and is more appropriate in treating hypertension
What is the half life?
- t 1/2
- The time it takes for 1/2 of the drug concentration to be eliminated.
- Metabolism and excretion effect the t 1/2 of a drug
- *water soluble drugs will have shorter half lives than lipid soluble drugs
- -lipid soluble drugs stay in the system longer
How do you calculate a drugs 1/2 life?
You must know the half life of the drug and then subtract 1/2 of dose every x-smount of hours
- Ex: 650mg of Asprin-Asprin has a 3hr half life
- After 3 hrs-325mg eliminated
- After 6 hrs-another 162 mg eliminated
- etc., etc.,
- *the half taken away is always from the NEW number, not the original dose!
What is the importance of a drug's 1/2 life?
It determines the scheduled doses of the drug to keep it in therapeutic range
What constitutes a short 1/2 life? What constitutes a long 1/2 life? Give an example of a drug with a long 1/2 life.
- Short t 1/2:3-8hrs
- Long t 1/2: 24 + hrs
- ----Ex. Digoxin has a t 1/2 f 36 hrs and takes several days for the body to clear the drug
What is hypersensitivity?
A reaction to a drug that is more profound than expected and which often results in an exaggerated immune response
What is Idiosyncrasy?
A reaction to a drug that is significantly different from what is expected
What is a drug's indication?
The medical condition for which the drug has proven therapeutic value
What does "Parenteral" mean?
- Any route of administration other than the digestive tract
- ex: intravenously, intramuscular, subcutaneously
What are Pharmacodynamics?
Study of the mechanisms by which drugs act to produce biochemical or physiological changes in the body
What are Pharmacokinetics?
- Study of how drugs enter the body, reach their site of action and are eliminated from the body
- Impact of the body on drugs
- Determining how much administered dose gets to its sites of action
What is a drug's potency?
The amount of drug required to produce 50% of the maximum response that the drug is capable of producing
ex. Morphine and codeine are both prescribed for pain relief. A smaller dose of morphine is required to achieve this effect, thus morphine is more potent than codeine
What is Potentiation?
The enhancement of a drug's effect by another drug
ex. promethazine may enhance the effects of morphine, just as alcohol enhances the effects of barbiturates
What is "Refractory"?
The failure of a client to response as expected to a certain medication
What is synergism?
The combined action of 2 or more drugs that is greater than the sum of the 2 drugs acting independently
What is a drug's therapeutic action?
The intended action of a drug given in an appropriate medical setting
What is a drug's therapeutic threshold?
The minimum amount of a drug that is required to cause the desired response
What is a drug's therapeutic index?
- The difference between the therapeutic threshold and the amount of the drug considered to be toxic
- *often referred to as the Safe and effective range of a drug
How do you calculate the Therapeutic Index?
- LD=Lethal dose
- ED= Therapeutic dose
- * The closer the ratio is to 1, the greater the danger of toxicity
- *low therapeutic index= narrow safety margin
- *high therapeutic index= wide safety margin
What is the therapeutic range?
The concentration of drug in plasma should be between the minimum concentration for obtaining desired action and the minimum toxic concentration
ex. Lithium: therapeutic range = .5-1.5 mg/ml
What does it mean when someone has a tolerance to a drug?
- Tolerance: the decreased sensitivity or response to a drug that occurs after repeated doses
- Increased doses are required to achieve the desired effect
- Most common in people who take a drug for an extended period of time
What is an untoward effect?
A side effect of a drug that is harmful to the client
What are some common toxic effects of drugs?
- Hepatotoxicity (liver)
- Nephrotoxocity (kidneys)
- Cardiotoxicity (heart)
May occur from cumulative effect when the body cannot metabolize one dose before the next dose is given
While there are no safe drugs, what are the three things that make an ideal drug?
- 1. Effectiveness
- 2. Safety
- 3. Selectivity
What does it mean for a drug to be selective?
It only produces the response it is supposed to
*unfortunately, most drugs are not strictly selective and thats where we get side effects
What side effects are all drugs capable of? What are some other common side effects?
- All are capable of nausea, vomiting, diarrhea
- Fatigue, headache, and drowsiness are also common
What are some additional properties of an ideal drug, besides the big three?
- Reversible action
- Ease of administration
- Freedom from drug interactions
- Low Cost
- Chemical Stability
- Simple generic name
What are four factors that determine the intensity of a drug response?
- 1. Administration
- 2. Pharmacokinetics
- 3. Pharmacodynamics
- 4. Sources of individual variation
What are four major pharmacokinetic processes?
- 1.Drug absorption
- 2. Drug distribution
- 3. Drug metabolism
- 4. Drug excretion
What is the main factor that influences drug absorption?
How the drug is administered
- ex. Food in the GI tract, stomach acidity, and blood flow to the GI tract influence absorption of oral meds
- ex. Small, lipid soluble drugs permeate plasma membranes more easily, such as those that work on the CNS, warfarin, and weight based drugs
What factors other than the route of administration effect drug absorption?
- Drug solubility
- Local conditions at site of administration
- Drug dosage
- Serum drug levels
What is the most common factor influencing drug distribution?
- The most common factor is membrane permeability
- In order for a drug to enter an organ, it must permeate all membranes that separate that organ from the drug
ex. benzodiazapines are very lipophilic, meaning they easily cross the gut wall and the blood brain barrier. Thus, they distribute to the brain easily and are very effective in treating anxiety and convulsions
What is the importance of drug metabolism and where does it most commonly take place?
- All drugs need to be metabolized before they can be excreted, as our body attempts to rid itself of any foreign substance
- In the pharmacology sense, metabolism refers to the process of making a drug water soluble for excretion
- *the P450 system in the liver is responsible for the metabolism of most drugs
How does drug excretion most commonly take place?
- Most drugs or toxins are excreted in the urine
- -->this means that most drugs are concentrated in the kidneys, leading to the frequency of nephrotoxicity and kidney damage
- Other can be excreted in feces or expired air
What is the difference between pharmacokinetics and pharmacodynamics?
Pharmacokinetics is what the body does to the drug and pharmacodynamics is what the drug does to the body
In terms of pharmacodynamics, how do most drugs work?
- Most drugs work through interactions with receptor sites
- These are protein coatings found on the other surface of the cell membrane
- Generally, when a drug binds or attaches to a receptor site, a chemical reaction occurs that initiates the desired physiological or therapeutic response
- *such drugs are called agonists
What are important determinants of drug response?
- Dosage, route, timing: determined by prescriber
- Medication errors: bad bad bad
- Client adherence: for a number of reasons
What variables can determine how a drug acts in an individual?
- Physiologic variables: like age, gender, and weight
- Pathological variables: like diminished function of liver or kidneys
- Genetic variables: like altered metabolism or predisposition to interactions
- Drug interactions: what else the individual is taking
What are NURSING RESPONSIBILITIES when it comes to administering medications?
- Understand how the drug works
- Administer the drug safely and effectively
- Assess drug effects
- Intervene to make the drug regimen more tolerable
- Provide client teaching about drugs and drug regimen
What are the 6 rights of medication?
- Right Drug
- Right Client
- Right Dose
- Right route
- Right time
- Right documentation
What are the two major areas that a nurse applies their pharmacological knowledge?
- Direct care of the client
- Client education
What is included in a pre-administration assessment?
- Collect baseline data: such and VS and pain scale to evaluate therapeutic responses and negative effects
- Identify high risk clients: those with liver and kidney impairement, genetic factors, drug allergies, pregnancy, elderly and pediatric
- tools you can use include: client history, physical examination and lab results
What are very important concepts related to dosages and administering Medications?
- READ THE MEDICATION ORDER CAREFULLY
- IDENTIFY THE CLIENT
- READ THE MEDICATION LABEL CAREFULLY
- DO NOT ADMINISTER ANY DRUG THAT YOU DO NOT UNDERSTAND THE REASON FOR ITS USE
- Implement any special handling or techniques for administration of that drug
What are some things to know to help minimize adverse effects?
- The major adverse effects the drug can produce
- The time when these reactions are likely to occur
- Early signs that an adverse reaction is developing
- Interventions that can minimize discomfort and harm
Describe an allergic reaction to a drug
- Allergic reaction: related to the immune response drug is perceived as foreign and antibodies are developed against the drug
- Reaction may be immediate or delayed for hours
- Symptoms: rash, urticaria, fever, diarrhea, n/v
What can the NURSE do to minimize adverse interactions?
- Take a thorough drug history!
- Advise the client to avoid OTC drugs that can interact with their prescriptions, such as aspirin and warfarin
- Monitor for common and known adverse effects
- Be alert for any other unknown reactions
What doe PRN mean and how does the nurse determine this?
- PRN means to give the medication as needed, such as with pain, anxiety, and sleep medication
- Nurses have the discretion to give this or offer this to the patient
- Nurse must know that reason for drug and be able to assess the clients medication needs
Summarize the nursing process for Medication
- Assessment: pre-administration
- Implementation: administration and measures to enhance therapeutic effects
- Evaluation and Interventions: Ongoing
- Client education: very important!
What are the important steps in evaluating Medications?
- Were the expected outcomes met?
- Objective statements from the client on effectiveness of medication
- Education Outcomes: client can verbalize how and when to take medication, when to call prescriber, and the expected side effects and adverse effects
What is the most reliable method to assess drug therapies?
- Randomized controlled trial
- -double blind
What is the different between Pre-clinical and Clinical Testing? What are the stages of clinical testing?
- Preclinical testing: drugs are tested for toxicities and pharmacokinetics, may take up t 5 years before testing in humans
- Clinical Testing: Phases
- -Phase I: Healthy Volunteers
- -Phase II and III: Client testing, small sample from 3-6 mo to determine dosage range, safety, effectiveness
- -Phase IV: Post Marketing Surveillance to observe effects in the general public
*limited for women and children during testing
What are the three types of drug names?
- Chemical Name
- Generic Name: tends to be more complicated to spell/pronounce/remember
- Trade Name: multiple trade names in US, diff trade names internationally