Week 1 Flashcards
Agonist
A drug that binds to and activates a receptor. Can be full, partial or inverse. A full agonist has high efficacy, producing a full response while occupying a relatively low proportion of receptors. A partial agonist has lower efficacy than a full agonist. It produces sub-maximal activation even when occupying the total receptor population, therefore cannot produce the maximal response, irrespective of the concentration applied. An inverse agonist produces an effect opposite to that of an agonist, yet it binds to the same receptor binding-site as an agonist.
Efficacy
Describes the way that agonists vary in the response they produce when they occupy the same number of receptors. High efficacy agonists produce their maximal response while occupying a relatively low proportion of the total receptor population. Lower efficacy agonists do not activate receptors to the same degree and may not be able to produce the maximal response.
Potency
A measure of the concentrations at which a drug is effective.
Desensitization
A reduction in response to an agonist while it is continuously present at the receptor, or progressive decrease in response upon repeated exposure to an agonist.
Duration of Action
The length of time that particular drug is effective. Duration of action is a function of several parameters including plasma half-life, the time to equilibrate between plasma and target compartments, and the off rate of the drug from its biological target.
Silent Antagonist
A drug that attenuates the effects of agonists or inverse agonists, producing a functional reduction in signal transduction. Affects only ligand-dependent receptor activation and displays no intrinsic activity itself. Also known as a neutral antagonist.
Half-life
The metabolic half-life of a drug in vivo is the time taken for its concentration in plasma to decline to half its original level. Half-life refers to the duration of action of a drug and depends upon how quickly the drug is eliminated from the plasma. The clearance and distribution of a drug from the plasma are therefore important parameters for the determination of its half-life.
Mechanism of action
Refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect.
Therapeutic Window
The amount of a medication between the amount that gives an effect (effective dose) and the amount that gives more adverse effects than desired effects. For instance, medication with a small pharmaceutical window must be administered with care and control, e.g. by frequently measuring blood concentration of the drug, since it easily loses effects or gives adverse effects.
B Max
The maximum amount of drug which can bind specifically to the receptors in a membrane preparation. Can be used to measure the density of the receptor site in a particular preparation.
What schedule drugs can APRNs prescribe?
Schedule II, III, IV and V drugs.
Schedule I drugs have no medical use and high potential for abuse (heroin, ecstasy, marijuana etc)
Pharmacokinetics
The study of drug movement through the body
Pharmacodynamics
The study of the biochemical and physiological effects of drugs on the body and molecular mechanisms by which those effects are produced.
Basic processes of Pharmacokinetics
- Absorption
- Distribution
- Metabolism
- Excretion
Absorption
A drug’s movement from the site of administration into the blood
Distribution
A drug’s movement from the site of administration into the blood
Metabolism
aka - biotransformation
Enzymatically mediated alteration of drug structure
Excretion
The movement of drugs and their metabolites out of the body
CYP450
Liver enzyme that metabolizes drugs which can be inhibited or induced by drugs and when this happens drug-drug interactions occur
Who determines prescriptive authority?
Determined by state law.
Who regulates prescriptive authority?
Under the jurisdiction of a professional health board (Nursing, medicine, pharmacy)
How does limited prescriptive authority impact patients within the healthcare system?
Creates barriers to quality, affordable, accessible patient care.
May prevent outreach to areas of greatest need (NP needs MD and none in the area)
Can increase prescription wait time (cosigning)
What are the key responsibilities of prescribing?
Having a sound understanding of drugs and the condition they are used to manage
What elements should be used to make prescribing decisions?
o Cost
o Current treatment guidelines
o Availability of medication
o Interactions with other medications
o Side effects
o Allergies
o Hepatic and renal function
o Need for monitoring
o Special populations (children and the elderly)
Pharmacokinetic changes in older adults
- Decreased ability of the liver to metabolize drugs
- higher concentration of drugs in the blood
- Decreased kidney function to excrete drugs - they stay in the bloodstream longer
- Increased drug sensitivity (reduced hepatic and renal elimination)
- Potential for increased variability in drug function
- potential for more intense effects
- need to reduce dosages
Older adults - changes in drug absorption
Slower rate of absorption, delayed drug response, gastric acidity may alter absorption
* Increased gastric pH
* Decreased surface area for absorption
* Decreased GI motility
* Delayed gastric emptying
* Decreased splanchnic blood floor
Older adults - changes in drug distribution
- Increased body fat reduced response to lipid soluble drugs
- Decreased lean mass
- Decreased total water lower distribution of water soluble drugs
- Decreased serum albumin decreased binding sites, more drug in the blood – higher intensity drug effect
- Decreased CO
Older adults - changes in drug metabolism
Increased drug half-life, prolonged medication response due to slower metabolism of drugs.
* Decreased hepatic blood flow
* Decreased hepatic mass
* Decreased activity of hepatic enzymes
Older adults - changes in drug excretion
Drug accumulation secondary to reduced renal excretion (causes adverse drug reactions)
* Decreased renal blood flow
* Decreased GFR
* Decreased tubular secretion
* Decreased number of nephrons
Beers Criteria
Identifies drugs with a high likelihood of causing adverse effects in older adults. Accordingly, drugs on this list should generally be avoided in adults older than 65 years except when the benefits are significantly greater than the risks
Impact/Outcomes of Polypharmacy
o Higher risk for drug interactions and adverse reactions
o More difficulty with medication adherence
Examples of CYP450 Inhibitors
Valproate
Isoniazid
Sulfonamides
Amiodarone
Chloramphenicol
Ketoconazole
Grapefruit juice
Quinidine
VISA debt inhibits spending on CK to look GQ
Function of CYP450 inhibitors
Act on the liver to slow the rate of metabolism causing an increase in active drug accumulation in the blood. This can lead to increased adverse effects and toxicity.
What do CYP450 inhibitors cause if not used correctly? (aka: What would the patient experience?)
The inhibiting drug inhibits metabolism of the second drug which can be beneficial but more often causes toxicity or adverse reactions.
Examples of CYP450 inducers
Barbiturates
St. john’s wort
Carbamazepine
Rifampin
Alcohol
Phenytoin
Griseofulvin
Phenobarbital
Sulfonylureas
BS CRAP GPS induces RAGE
Function of CYP450 inducers
Inducers act on the liver to stimulate enzyme synthesis. By increasing the rate of drug metabolism the amount of active drugs is decreased and plasma levels fall. This may result in medication not achieving therapeutic levels.
Function of CYP450 inducers
Inducers act on the liver to stimulate enzyme synthesis. By increasing the rate of drug metabolism the amount of active drugs is decreased and plasma levels fall. This may result in medication not achieving therapeutic levels.
What do inducers cause if not used correctly? (aka: What would the patient experience?)
- Medication taken along with an inducer would need its dosage increased to be effective.
- When an inducer is discontinued dosages of other drugs need to be lowered to avoid dangerous high drug levels.
What happens when someone has a poor metabolism phenotype?
The poor metabolism of drugs can reduce the benefits of therapy by being unable to activate medication through metabolism into its active form causing treatment to fail.
Poor metabolism can cause the standard dose of a medication to accumulate to high levels in the blood causing toxicity.
What does the U.S. Food and Drug Administration regulate when it comes to medications?
Regulates the safety and effectiveness of drugs sold in the united states
Reasons for medication non-adherence
o Forgetfulness
o Lack of planning
o Cost
o Dissatisfaction
o Altered dosing
What are black box warnings?
Strongest safety warning a drug can have and still remain on the market. They alert the provider to:
* Potentially severe side effects (life threatening dysrhythmias, suicidality, fetal harm)
* Ways to prevent or reduce harm
Contain a summary of the adverse effects of concern
Why are black box warnings issued?
To alert the patient and provider to the risk of harm from taking the medication
Neonate and infant drug absorption
(general development and when absorption would reach adults levels)
Kidneys don’t fully develop until a few months after birth meaning they have a limited capacity to excrete drugs
Gastric emptying is prolonged and irregular and reaches adult level by 6-8 months old
Delayed absorption in the intestine due to delayed gastric emptying
Gastric acidity is low and does not reach adult values for 2 years. absorption of acid-labile drugs is increased
Transdermal absorption is increased due to thin skin and higher blood flow
Blood brain barrier not fully developed
Hepatic metabolism is low – complete maturation of liver by 1 year old
Renal excretion – renal blood flow, GFR and active tubular secretion are low – like adults by 1 year old.
Common fears with genetic testing
o Financial cost
o Fear of results
o Fear of discrimination based on results
What are some of the physiologic changes that occur in the body when a woman is pregnant that can change the pharmacodynamic and pharmacokinetic properties of many drugs?
o Increased GFR increases excretion
o Slower digestion
o Decreased tone and mobility of bowel
o Increase hepatic metabolism of some drugs
During what trimester is a pregnant woman most at risk for adverse drug reactions with potential long-term consequences?
First trimester (fetus most at risk due to rapid growth)
What medications do we know are teratogenic?
o Hormonal
o Antidepressant
o Antibiotic
o Antiepileptic drugs
How is absorption of intramuscular medication different in neonates?
Decreased absorption due to low blood flow in the muscles due in the first few days of life.
Why is absorption of medication in the stomach increased in infancy?
Delayed gastric emptying until 6-8 months causes increased absorption
What are some medications that should be avoided in the pediatric patient?
o Aspirin
o Tetracycline (discoloration of teeth)
o Antibiotics
o Sulfonamides
o Glucocorticoids
o Levofloxacin (spontaneous tendon rupture)
What should be included in medication administration patient education?
Dosing, route, how often to take, how long to take, side effects, drug storage, desired response and adverse reactions
What are some things that put elderly patients at higher risk for adverse drug reactions?
o Reduced renal function
o Polypharmacy (5+ medications on a daily basis)
o Comorbidities
o Decreased liver function
o Greater severity of illness
o Patient adherence
o Inadequate supervision of long-term therapy
How can we as healthcare providers decrease the likelihood of an elderly patient experiencing an adverse drug reaction?
o Complete medication/medical history
o Medication review yearly
o Encouraging the use of one pharmacy
o Lab values
o Look at drug interactions when prescribing new drugs
o Consider change with age (adjust dosing)
o BEERS criteria list
How can we promote medication adherence with our elderly patients?
o Explain the importance/purpose of medications
o Include family members
o Try to make dosing easy - simplify regimen
Pill dispenser
o Being aware of cost
o Clearly labeled/ easy to open
o Support system
Why do nitrates need to be taken no later than 4 pm?
You need a nitrate free interval so that a tolerance doesn’t develop (8 hours usually overnight)
What are the nine factors that impact the outcome of medication according to Rosenthal and Burcham?
o Genetics
o Pharmacogenomics
o Gender
o Race
o Body weight
o Age
o Tolerance
o Placebo effect
o Pathophysiology of medication
Do we need informed consent for genetic testing?
Yes
What is the purpose of the Genetic Information Non-Discriminatory Act?
o To prevent discrimination based on genetic predisposition
o Protects the patient from discrimination by employers and insurers
What is the difference between NP practice authority and prescriptive authority?
o Practice authority is whether you can practice without physician oversight
o Prescriptive authority is the ability to write prescriptions independently
What is full practice authority?
Ability to practice independently (assess, diagnose, evaluate, treat) without physician oversight
What is reduced practice authority?
o Able to practice with oversight from a physician
o Provider for first 5 years then independently
o Willing to have practitioner to
o Limited in at least one area of practice
o Collaborative agreement with a licensed provider
What is restricted practice authority?
Need a doctor on site and available
What are the components of an Rx?
o Patient information
o Provider information
o Name of drug
o Dose of drug
o Route of administration
o Dose frequency
o Refills
o Quantity
o Directions for use
What are some potential problems that may arise with written prescriptions?
o legibility
o incorrect abbreviations
o misspelling
o don’t contain all elements
o tamper resistant scripts
What are some reasons for monitoring drug therapy?
o Assess effects – is it therapeutic
o Adverse reactions
o Checking for abuse