NR565 Week 1 Study Guide (w/ Quiz 1)

Question

Answer

What determines an NP’s prescriptive authority?

State law and licensure level (NP, PA, MD) determine authority. Some states require collaborative agreements, and controlled substance prescribing requires DEA registration.

In a restricted-practice state, what must an NP do to prescribe?

They must have formal physician oversight for certain aspects of care.

What must every prescription legally include?

Prescriber details (name, NPI, DEA if controlled), patient info, drug name/strength/form, directions, quantity, refills, and signature.

What is the primary legal risk of off-label prescribing?

Patients may file complaints or lawsuits if adverse effects occur, since use is outside FDA-approved labeling.

What are the four pharmacokinetic processes?

Absorption, Distribution, Metabolism, and Excretion (ADME).

What determines how much drug reaches systemic circulation?

Absorption —> influenced by route, pH, motility, food, and bioavailability.

Why do oral drugs often have reduced bioavailability?

Because of first-pass hepatic metabolism before reaching systemic circulation.

How does urine pH affect drug excretion?

Acidic urine enhances excretion of weak bases; alkaline urine enhances excretion of weak acids (e.g., sodium bicarb for aspirin overdose).

What is protein binding, and why is it important?

Only unbound drug is active. High protein binding (e.g., warfarin) prolongs action but increases interaction risk. Low albumin increases toxicity risk.

Compare lipid- vs. water-soluble drugs in distribution.

Lipid-soluble drugs cross membranes easily, have wider distribution, and longer half-lives; water-soluble drugs stay in plasma and clear faster.

What does a high volume of distribution (Vd) indicate?

A drug distributes widely into tissues (lipophilic, long-acting).

Where does most drug metabolism occur?

In the liver via CYP450 enzymes; also in intestines, lungs, and kidneys.

Describe Phase I vs Phase II metabolism.

Phase I: oxidation, reduction, or hydrolysis (adds/reveals polar group). Phase II: conjugation (adds molecule like glucuronide for excretion).

What’s the clinical impact of CYP450 induction and inhibition?

Inducers (e.g., rifampin, St. John’s Wort) decrease drug levels; inhibitors (e.g., ketoconazole, grapefruit juice) increase levels and toxicity risk.

Why does genetic variation in CYP2D6 matter?

It controls codeine —> morphine conversion: poor metabolizers get no relief; ultra-rapid metabolizers risk toxicity.

Which renal process filters only unbound drug?

Glomerular filtration.

Why must CrCl or eGFR be checked before dosing renally-cleared drugs?

Decreased clearance prolongs half-life and increases toxicity risk (e.g., lithium, digoxin).

How do agonists and antagonists differ?

Agonists activate receptors (increase effect); antagonists block them (decrease effect).

Give an example of a synergistic drug interaction.

Benzodiazepines + opioids —> severe CNS depression.

What’s the main difference between additive and synergistic effects?

Additive = sum of effects (1+1=2); synergistic = greater than sum (1+1>2).

What determines a drug’s half-life?

Combined rates of metabolism and excretion.

How long does it take to reach steady state?

Usually 4-5 half-lives with consistent dosing.

What are the top strategies to minimize ADRs?

Use the lowest effective dose, monitor labs, review for interactions, avoid polypharmacy, and educate patients.

What do boxed warnings signify?

FDA alerts for life-threatening/disabling risks (e.g., SSRIs increase suicidality) requiring extra vigilance.

When is the fetus most at risk for teratogenicity?

During organogenesis (weeks 3-8 of first trimester).

Give two examples of teratogens and their fetal effects.

ACE inhibitors —> renal/skull defects; valproic acid —> neural tube defects.

What are key pharmacokinetic changes in pregnancy?

Increase blood volume & GFR (faster excretion), Decrease albumin (increases free drug), increases hepatic metabolism.

Why should pediatric dosing always be weight-based?

Children —> organ systems are immature; mg/kg dosing ensures safety and accuracy.

How does aging affect pharmacokinetics?

↓ GFR & liver enzymes → slower clearance, longer half-life, ↑ toxicity risk.

Why is diphenhydramine inappropriate for older adults?

Strong anticholinergic effects → confusion, delirium, falls, urinary retention.

What absorption differences exist in infants?

Higher gastric pH and irregular peristalsis cause delayed and unpredictable absorption.

Name common hepatotoxic drug classes.

Acetaminophen, valproic acid, isoniazid/rifampin, statins, and systemic azoles like ketoconazole.

What labs monitor for hepatotoxicity?

AST, ALT, ALP, and bilirubin.

How does pharmacogenomics improve prescribing?

It helps predict metabolism speed and adverse reaction risk based on genetic polymorphisms.

Which CYP enzymes show notable ancestry-related variability?

CYP2D6 and CYP2C19 — they influence metabolism of codeine, SSRIs, and clopidogrel.