Pharmacotherapeutics Flashcards
(40 cards)
1
Q
Prescriptive Authority
A
- Granted by each state and gives APRNs the legal right to prescribe drugs
- Boards of Nursing governs prescriptive authority
- Federal laws and regulations surrounding controlled substances are created and enforced by the DEA
2
Q
What to ask patient before prescribing medication?
A
- Do you have allergies?
- What meds are you taking?
- Are you pregnant or breastfeeding?
- Have you taken this medicine before?
- Do you have liver or kidney problems?
3
Q
What to ask yourself before prescribing a medication?
A
- Is there a need for medication to treat the condition?
- Is this the most appropriate medication?
- Are there contraindications?
- Is this the correct dose/route?
- What is the cost?
4
Q
Pharmacokinetics
A
- involves the effects of drug absorption, distribution, metabolism, and excretion processes
- “how the body affects the drug”
5
Q
Pharmacodynamics
A
- refers to the relationship between drug concentrations and drug effects
- “how the drug affects the body”
6
Q
Pharmacogenomics
A
- a relatively new field of study that explores an individual’s response, or lack thereof, to a medication
7
Q
Speed of absorption depends on what?
A
- route
- dosage
- patient-specific characteristics
8
Q
Bioavailability
A
- the amount of drug that reaches circulation and end-target organ tissue relative to dose
- differs between dose forms such as delayed-release (DR) vs extended-release (ER)
9
Q
Lipophilicity
A
- ability for chemicals to dissolve in or pass through lipid membranes
- “Fat loving”
10
Q
Hydrophilicity
A
- molecule that is attracted to water and dissolves in water
- “water loving”
11
Q
How does the presence of food affect absorption?
A
- the presence of food may decrease maximum concentration (Cmax) and may delay the time required to meet peak concentration (Tmax)
12
Q
Permeable glycoproteins
A
- drug transport proteins that actively pump (efflux) drugs and other foreign chemicals out of cells
- (P-gp)
- the impact of P-gp are most significant for drugs with a narrow therapeutic index (small window b/t toxic and therapeutic serum concentrations) and drugs with slow dissolution rates
- there is some overlap between substrates of P-gp and CYP450
13
Q
Drug half-life
A
- time required for the amount of drug in the body to decrease by half
14
Q
Therapeutic concentration range
A
- range of serum concentration minimally required to elicit the desired response and avoid toxicity
15
Q
Binding affinity
A
- propensity of any drug to bind to plasma proteins
16
Q
Loading dose
A
- amount of drug to administered a the 1st dose to achieve fastest therapeutic concentration and avoiding toxicity
17
Q
Steady state
A
- optimal plateau serum concentration achieved after five T1/2 and absorption equals elimination
18
Q
Cmax
A
- max serum concentration achieved in a specific area of the body after the drug has been administered and prior to a second dose
19
Q
Cmin
A
- minimum serum concentration of the drug in the body
20
Q
Volume of distribution (Vd)
A
- max extent of a drug’s ability to migrate into tissues and fluids in the body
- Vd varies with PK/PD and physiological characteristics of the patient
21
Q
Plasma protein binding
A
- ability of drug to bind to plasma proteins which varies on amount of protein in the blood and the affinity of the given drug
- proteins include: serum albumin, lipoprotein, glycoprotein, and various globulins
22
Q
Distribution
A
- describes the migration of a drug in body tissue and compartments (e.g. blood, interstitial fluids, cerebrospinal fluids, muscle, fatty adipose tissue, etc.)
23
Q
What does large Vd indicate?
A
- low plasma concentration relative to the amount of drug in the body indicates extensive drug distribution to the tissue and large Vd
24
Q
What does small Vd indicate?
A
- may indicate the drug is associated with high plasma protein binding, inhibiting the distribution of the drug from the plasma
25
Metabolism
- refers to the biotransformation of a drug by chemical reactions (e.g. oxidation, deamidation, conjugation) to form drug metabolites that are chemically distinct for the parent drug
- drug metabolism is a form of elimination
26
Where does drug metabolism take place?
- takes place in the kidney, lungs, and GI tract. However, the liver is the primary organ involved in drug metabolism
27
First-pass effect
- potential extraction after absorption through the gut and before it enters the systemic circulation
28
Phase I oxidation
- process of metabolism in which chemical reactions via CYP450 transform chemical agents (i.e. meds) into metabolites that consists of more hydrophilic polar molecules to allow for more efficient excretion
- Phase I metabolism also involves chemical reactions and hydrolysis
29
Phase II conjugation
- metabolism converts a parent drug into more hydrophilic polar molecule to allow for more efficient excretion
- drugs metabolized via phase II reactions are really excreted and may or may not have been previously involved in phase metabolism
- phase II enzymes (ST, GST, UGT) are responsible for this conjugation process
30
Drugs that inhibit enzyme activity and decrease metabolism
- grapefruit juice
- protease inhibitors
- azoles
31
Drugs that induce activity and increases metabolism
- St. Johns wort
- Phenytoin
- Rifampin
32
Factors that influence drug metabolism
- males metabolize drugs more efficiently than females
- older adults metabolize less efficiently than younger adults
- genetic differences translate into individual differences such as being an extensive metabolizer vs a poor metabolizer
- poor metabolizers may experience exaggerated effects
- extensive metabolizers may experience suboptimal/poor drug responses
33
Excretion
- in addition to elimination via metabolism, drugs may be eliminated via excretion into the urine or bile
34
Excretion into the urine by the kidneys depends of what 3 processes?
1. glomerular filtration
2. tubular excretion
3. tubular reabsorption
35
GFR
- rate at which blood passes through the glomeruli, the small filters found in the kidney
- is often used to assess renal function and is measured in mL/min
- GFR < 60 mL/min is considered sufficiently reduced
- Low GFR indicated renal compromise and may require dose adjustment
36
Are hydrophilic or lipophilic drugs more likely to be reabsorbed?
Lipophilic
37
Renal clearance
- the ability and rate that waste (i.e. drug metabolites) are excreted through the kidneys into the urine
38
Creatinine clearance (CrCl)
- rate by which creatinine, a by-product of muscle metabolism, is excreted through the kidneys and into the urine
- serum creatinine are reduced in older adults due to decrease in overall lean muscle mass
39
Dialysis of drugs
- process of medication, wastes, and/or drug metabolites are removed from the body when the kidneys are unable
- hemodialysis are peritoneal dialysis both perform filtering
40
Cockcroft-Gault equation for estimating creatinine clearance
- this formula is still one of the best approaches for medication adjustments based on renal concerns
- obese patients will need additional consideration taken into account relative to excretions
- older patients should not have their serum creatinine rounded up to 1 mg/dL. However, non-elderly rounding CrCl and GFR will make calculation easier
- CrCl and GFR are different measurements and are not interchangeable
