Pharmacotherapeutics

Question 1

Prescriptive Authority

Answer 1

• 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

Question 2

What to ask patient before prescribing medication?

Answer 2

• 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?

Question 3

What to ask yourself before prescribing a medication?

Answer 3

• 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?

Question 4

Pharmacokinetics

Answer 4

• involves the effects of drug absorption, distribution, metabolism, and excretion processes
• “how the body affects the drug”

Question 5

Pharmacodynamics

Answer 5

• refers to the relationship between drug concentrations and drug effects
• “how the drug affects the body”

Question 6

Pharmacogenomics

Answer 6

• a relatively new field of study that explores an individual’s response, or lack thereof, to a medication

Question 7

Speed of absorption depends on what?

Answer 7

• route
• dosage
• patient-specific characteristics

Question 8

Bioavailability

Answer 8

• 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)

Question 9

Lipophilicity

Answer 9

• ability for chemicals to dissolve in or pass through lipid membranes
• “Fat loving”

Question 10

Hydrophilicity

Answer 10

• molecule that is attracted to water and dissolves in water
• “water loving”

Question 11

How does the presence of food affect absorption?

Answer 11

• the presence of food may decrease maximum concentration (Cmax) and may delay the time required to meet peak concentration (Tmax)

Question 12

Permeable glycoproteins

Answer 12

• 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

Question 13

Drug half-life

Answer 13

• time required for the amount of drug in the body to decrease by half

Question 14

Therapeutic concentration range

Answer 14

• range of serum concentration minimally required to elicit the desired response and avoid toxicity

Question 15

Binding affinity

Answer 15

• propensity of any drug to bind to plasma proteins

Question 16

Loading dose

Answer 16

• amount of drug to administered a the 1st dose to achieve fastest therapeutic concentration and avoiding toxicity

Question 17

Steady state

Answer 17

• optimal plateau serum concentration achieved after five T1/2 and absorption equals elimination

Question 18

Cmax

Answer 18

• max serum concentration achieved in a specific area of the body after the drug has been administered and prior to a second dose

Question 19

Cmin

Answer 19

• minimum serum concentration of the drug in the body

Question 20

Volume of distribution (Vd)

Answer 20

• 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

Question 21

Plasma protein binding

Answer 21

• 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

Question 22

Distribution

Answer 22

• describes the migration of a drug in body tissue and compartments (e.g. blood, interstitial fluids, cerebrospinal fluids, muscle, fatty adipose tissue, etc.)

Question 23

What does large Vd indicate?

Answer 23

• low plasma concentration relative to the amount of drug in the body indicates extensive drug distribution to the tissue and large Vd

Question 24

What does small Vd indicate?

Answer 24

• may indicate the drug is associated with high plasma protein binding, inhibiting the distribution of the drug from the plasma

Question 25

Metabolism

Answer 25

• 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

Question 26

Where does drug metabolism take place?

Answer 26

• takes place in the kidney, lungs, and GI tract. However, the liver is the primary organ involved in drug metabolism

Question 27

First-pass effect

Answer 27

• potential extraction after absorption through the gut and before it enters the systemic circulation

Question 28

Phase I oxidation

Answer 28

• 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

Question 29

Phase II conjugation

Answer 29

• 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

Question 30

Drugs that inhibit enzyme activity and decrease metabolism

Answer 30

• grapefruit juice
• protease inhibitors
• azoles

Question 31

Drugs that induce activity and increases metabolism

Answer 31

• St. Johns wort
• Phenytoin
• Rifampin

Question 32

Factors that influence drug metabolism

Answer 32

• 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

Question 33

Excretion

Answer 33

• in addition to elimination via metabolism, drugs may be eliminated via excretion into the urine or bile

Question 34

Excretion into the urine by the kidneys depends of what 3 processes?

Answer 34

1. glomerular filtration
2. tubular excretion
3. tubular reabsorption

Question 35

GFR

Answer 35

• 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

Question 36

Are hydrophilic or lipophilic drugs more likely to be reabsorbed?

Answer 36

Lipophilic

Question 37

Renal clearance

Answer 37

• the ability and rate that waste (i.e. drug metabolites) are excreted through the kidneys into the urine

Question 38

Creatinine clearance (CrCl)

Answer 38

• 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

Question 39

Dialysis of drugs

Answer 39

• 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

Question 40

Cockcroft-Gault equation for estimating creatinine clearance

Answer 40

• 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