NR 565 /NR 565 ADVANCED PHARMACOLOGY
FUNDAMENTS
ACTUAL EXAM QUESTIONS AND EXPLAINED ANSWERS
1. Describe the pharmacokinetic factors that could influence drug absorption in a
68-year-old patient with chronic kidney disease who is starting a new oral
antihypertensive
• Gastrointestinal changes with aging: Gastric acid secretion declines in elderly patients,
and gastric emptying is often delayed. These changes slow the dissolution of solid oral
dosage forms and delay the time to peak plasma concentration. Drugs that require an
acidic environment for solubility, such as certain calcium channel blockers, may have
reduced absorption.
• Intestinal perfusion: Chronic kidney disease can reduce splanchnic blood flow.
Adequate perfusion is necessary for passive and facilitated diffusion of drugs. Reduced
perfusion slows absorption, particularly for drugs absorbed via carrier-mediated
transport.
• Altered gastric pH: Proton pump inhibitors, H2 blockers, and age-related
hypochlorhydria can alter drug ionization, solubility, and subsequent absorption. Drugs
with pH-dependent solubility (e.g., certain ACE inhibitors) may have reduced
bioavailability.
• Uremic toxins: Accumulated uremic toxins in CKD can interfere with intestinal drug
transporters (e.g., P-glycoprotein), impacting the uptake of medications.
• Polypharmacy and drug interactions: Concomitant medications like antacids,
cholestyramine, or dietary fibers can bind to drugs and reduce absorption.
, • Clinical implications: Start with lower doses, monitor blood pressure response closely,
consider administering medications with or without food depending on the drug's
absorption profile, and educate patients to avoid taking interacting substances
simultaneously.
2. Discuss how genetic polymorphisms affecting cytochrome P450 enzymes can
alter drug metabolism in patients prescribed warfarin
• CYP2C9 polymorphisms: Alleles *2 and *3 result in reduced enzymatic activity.
Warfarin metabolism is slowed, leading to higher plasma concentrations and increased
risk of bleeding. Patients with these variants often require lower doses.
• VKORC1 polymorphisms: Variants affect warfarin sensitivity by altering the vitamin K
epoxide reductase complex. Some patients require significantly lower doses to achieve
therapeutic INR.
• Clinical implication: Genetic testing for CYP2C9 and VKORC1 may help individualize
dosing and reduce risk of hemorrhage.
• Monitoring strategy: Frequent INR checks during initiation, gradual titration, and
monitoring for signs of bleeding or thrombosis. Educate patients on dietary vitamin K,
drug interactions, and importance of adherence.
3. Outline the clinical considerations for prescribing beta-blockers in elderly
patients with both hypertension and chronic obstructive pulmonary disease
(COPD)
• Choice of beta-blocker: Cardio selective beta-1 blockers (e.g., metoprolol, bisoprolol)
minimize beta-2 mediated bronchospasm. Non-selective agents (e.g., propranolol) may
exacerbate pulmonary symptoms.
• Baseline pulmonary assessment: Spirometry or peak flow should be obtained before
therapy initiation to establish baseline lung function.
• Dosing strategy: Start at the lowest effective dose and titrate slowly, monitoring for both
cardiovascular and respiratory responses.
• Monitoring: Heart rate, blood pressure, signs of bronchospasm (wheezing, dyspnea), and
exercise tolerance should be observed closely.
, • Patient education: Emphasize the importance of reporting worsening shortness of
breath, wheezing, or cough. Warn against abrupt discontinuation to prevent rebound
hypertension or tachycardia.
4. Explain the mechanism by which metformin can cause lactic acidosis in
patients with renal impairment
• Renal excretion: Metformin is excreted unchanged by the kidneys. CKD leads to drug
accumulation, increasing systemic exposure.
• Mitochondrial inhibition: Metformin inhibits complex I of the mitochondrial respiratory
chain in hepatocytes, decreasing oxidative phosphorylation and promoting anaerobic
metabolism, which increases lactate production.
• Impaired lactate clearance: In renal impairment, lactate is less efficiently removed,
leading to accumulation.
• Clinical consequences: High lactate levels result in metabolic acidosis with a high anion
gap, which can be life-threatening.
• Management and prevention: Avoid metformin in patients with eGFR <30
mL/min/1.73 m², monitor renal function periodically, educate patients on symptoms
(nausea, vomiting, rapid breathing, lethargy), and discontinue immediately if lactic
acidosis is suspected.
5. Highlight the differences in drug distribution between neonates and older
children and their implications for dosing
• Total body water: Neonates have higher total body water (up to 75–80% of body
weight), increasing the volume of distribution for hydrophilic drugs like
aminoglycosides, leading to lower plasma concentrations and potentially requiring higher
weight-based doses.
• Fat content: Neonates have lower adipose tissue, reducing distribution of lipophilic
drugs (e.g., benzodiazepines), potentially resulting in higher plasma levels and toxicity.
• Plasma protein binding: Neonates have lower albumin and α1-acid glycoprotein,
increasing free drug concentrations for protein-bound medications and raising toxicity
risk.
, • Clinical implications: Dose adjustments based on age, weight, and developmental
pharmacokinetics are essential. Therapeutic drug monitoring is recommended,
particularly for narrow therapeutic index drugs.
6. Give the rationale for monitoring serum potassium in patients receiving both
digoxin and loop diuretics
• Mechanistic interaction: Loop diuretics (e.g., furosemide) increase renal potassium
excretion, causing hypokalemia. Low potassium enhances digoxin binding to myocardial
Na⁺/K⁺-ATPase, increasing digoxin toxicity risk.
• Toxicity consequences: Hypokalemia plus digoxin can precipitate arrhythmias, nausea,
vomiting, visual disturbances, and potentially fatal ventricular arrhythmias.
• Monitoring strategy:
• Check potassium levels before and during therapy, especially after dose changes
• Adjust digoxin or diuretic dose accordingly
• Educate patients on dietary potassium intake and signs of toxicity (muscle weakness,
palpitations, confusion)
7. Name the major drug classes used for seizure management in pediatric
patients and discuss the age-specific considerations for each
• Benzodiazepines (e.g., lorazepam, diazepam): Used for acute seizures or status
epilepticus; monitor for sedation, respiratory depression, and paradoxical agitation in
children.
• Barbiturates (phenobarbital): Often used in neonates; may affect neurodevelopment,
cognitive function, and behavior long-term.
• Valproate: Broad-spectrum anticonvulsant; monitor hepatic function, platelets, and
ammonia levels; dose carefully in children under 2 years due to risk of hepatotoxicity.
• Phenytoin: Highly protein-bound, narrow therapeutic index; monitor serum levels and
consider interactions with other medications.
• Levetiracetam: Favorable safety profile; dose adjustments needed in renal impairment;
monitor for behavioral changes.
FUNDAMENTS
ACTUAL EXAM QUESTIONS AND EXPLAINED ANSWERS
1. Describe the pharmacokinetic factors that could influence drug absorption in a
68-year-old patient with chronic kidney disease who is starting a new oral
antihypertensive
• Gastrointestinal changes with aging: Gastric acid secretion declines in elderly patients,
and gastric emptying is often delayed. These changes slow the dissolution of solid oral
dosage forms and delay the time to peak plasma concentration. Drugs that require an
acidic environment for solubility, such as certain calcium channel blockers, may have
reduced absorption.
• Intestinal perfusion: Chronic kidney disease can reduce splanchnic blood flow.
Adequate perfusion is necessary for passive and facilitated diffusion of drugs. Reduced
perfusion slows absorption, particularly for drugs absorbed via carrier-mediated
transport.
• Altered gastric pH: Proton pump inhibitors, H2 blockers, and age-related
hypochlorhydria can alter drug ionization, solubility, and subsequent absorption. Drugs
with pH-dependent solubility (e.g., certain ACE inhibitors) may have reduced
bioavailability.
• Uremic toxins: Accumulated uremic toxins in CKD can interfere with intestinal drug
transporters (e.g., P-glycoprotein), impacting the uptake of medications.
• Polypharmacy and drug interactions: Concomitant medications like antacids,
cholestyramine, or dietary fibers can bind to drugs and reduce absorption.
, • Clinical implications: Start with lower doses, monitor blood pressure response closely,
consider administering medications with or without food depending on the drug's
absorption profile, and educate patients to avoid taking interacting substances
simultaneously.
2. Discuss how genetic polymorphisms affecting cytochrome P450 enzymes can
alter drug metabolism in patients prescribed warfarin
• CYP2C9 polymorphisms: Alleles *2 and *3 result in reduced enzymatic activity.
Warfarin metabolism is slowed, leading to higher plasma concentrations and increased
risk of bleeding. Patients with these variants often require lower doses.
• VKORC1 polymorphisms: Variants affect warfarin sensitivity by altering the vitamin K
epoxide reductase complex. Some patients require significantly lower doses to achieve
therapeutic INR.
• Clinical implication: Genetic testing for CYP2C9 and VKORC1 may help individualize
dosing and reduce risk of hemorrhage.
• Monitoring strategy: Frequent INR checks during initiation, gradual titration, and
monitoring for signs of bleeding or thrombosis. Educate patients on dietary vitamin K,
drug interactions, and importance of adherence.
3. Outline the clinical considerations for prescribing beta-blockers in elderly
patients with both hypertension and chronic obstructive pulmonary disease
(COPD)
• Choice of beta-blocker: Cardio selective beta-1 blockers (e.g., metoprolol, bisoprolol)
minimize beta-2 mediated bronchospasm. Non-selective agents (e.g., propranolol) may
exacerbate pulmonary symptoms.
• Baseline pulmonary assessment: Spirometry or peak flow should be obtained before
therapy initiation to establish baseline lung function.
• Dosing strategy: Start at the lowest effective dose and titrate slowly, monitoring for both
cardiovascular and respiratory responses.
• Monitoring: Heart rate, blood pressure, signs of bronchospasm (wheezing, dyspnea), and
exercise tolerance should be observed closely.
, • Patient education: Emphasize the importance of reporting worsening shortness of
breath, wheezing, or cough. Warn against abrupt discontinuation to prevent rebound
hypertension or tachycardia.
4. Explain the mechanism by which metformin can cause lactic acidosis in
patients with renal impairment
• Renal excretion: Metformin is excreted unchanged by the kidneys. CKD leads to drug
accumulation, increasing systemic exposure.
• Mitochondrial inhibition: Metformin inhibits complex I of the mitochondrial respiratory
chain in hepatocytes, decreasing oxidative phosphorylation and promoting anaerobic
metabolism, which increases lactate production.
• Impaired lactate clearance: In renal impairment, lactate is less efficiently removed,
leading to accumulation.
• Clinical consequences: High lactate levels result in metabolic acidosis with a high anion
gap, which can be life-threatening.
• Management and prevention: Avoid metformin in patients with eGFR <30
mL/min/1.73 m², monitor renal function periodically, educate patients on symptoms
(nausea, vomiting, rapid breathing, lethargy), and discontinue immediately if lactic
acidosis is suspected.
5. Highlight the differences in drug distribution between neonates and older
children and their implications for dosing
• Total body water: Neonates have higher total body water (up to 75–80% of body
weight), increasing the volume of distribution for hydrophilic drugs like
aminoglycosides, leading to lower plasma concentrations and potentially requiring higher
weight-based doses.
• Fat content: Neonates have lower adipose tissue, reducing distribution of lipophilic
drugs (e.g., benzodiazepines), potentially resulting in higher plasma levels and toxicity.
• Plasma protein binding: Neonates have lower albumin and α1-acid glycoprotein,
increasing free drug concentrations for protein-bound medications and raising toxicity
risk.
, • Clinical implications: Dose adjustments based on age, weight, and developmental
pharmacokinetics are essential. Therapeutic drug monitoring is recommended,
particularly for narrow therapeutic index drugs.
6. Give the rationale for monitoring serum potassium in patients receiving both
digoxin and loop diuretics
• Mechanistic interaction: Loop diuretics (e.g., furosemide) increase renal potassium
excretion, causing hypokalemia. Low potassium enhances digoxin binding to myocardial
Na⁺/K⁺-ATPase, increasing digoxin toxicity risk.
• Toxicity consequences: Hypokalemia plus digoxin can precipitate arrhythmias, nausea,
vomiting, visual disturbances, and potentially fatal ventricular arrhythmias.
• Monitoring strategy:
• Check potassium levels before and during therapy, especially after dose changes
• Adjust digoxin or diuretic dose accordingly
• Educate patients on dietary potassium intake and signs of toxicity (muscle weakness,
palpitations, confusion)
7. Name the major drug classes used for seizure management in pediatric
patients and discuss the age-specific considerations for each
• Benzodiazepines (e.g., lorazepam, diazepam): Used for acute seizures or status
epilepticus; monitor for sedation, respiratory depression, and paradoxical agitation in
children.
• Barbiturates (phenobarbital): Often used in neonates; may affect neurodevelopment,
cognitive function, and behavior long-term.
• Valproate: Broad-spectrum anticonvulsant; monitor hepatic function, platelets, and
ammonia levels; dose carefully in children under 2 years due to risk of hepatotoxicity.
• Phenytoin: Highly protein-bound, narrow therapeutic index; monitor serum levels and
consider interactions with other medications.
• Levetiracetam: Favorable safety profile; dose adjustments needed in renal impairment;
monitor for behavioral changes.
