CMT Pharmacology and Medication Actions 2 — Questions and Answers
Question 1: A medication's 'half-life' refers to:
- The time it takes for the drug to reach full effect
- The time required for half the drug to be eliminated from the body (Correct answer)
- Half the recommended dosage
- The shelf life of the medication
Correct answer: The time required for half the drug to be eliminated from the body
Half-life is the time required for the plasma concentration of a drug to decrease by 50% through metabolism and elimination.
Half-life (t½) is a fundamental pharmacokinetic parameter. After one half-life, 50% of the drug remains; after two half-lives, 25%; after three, 12.5%; and after five half-lives, approximately 97% is eliminated (drug is considered cleared). Half-life determines dosing frequency: short half-life drugs (2-4 hours) may require dosing every 4-6 hours, while long half-life drugs (24+ hours) may be dosed once daily. Steady state (consistent blood levels) is achieved after approximately 5 half-lives of regular dosing. Factors affecting half-life include liver function, kidney function, age, and drug interactions.
Question 2: Which class of medications is commonly used to lower blood pressure by blocking beta-adrenergic receptors?
- ACE inhibitors
- Beta-blockers (Correct answer)
- Diuretics
- Calcium channel blockers
Correct answer: Beta-blockers
Beta-blockers reduce blood pressure and heart rate by blocking the effects of epinephrine on beta-adrenergic receptors.
Beta-blockers (beta-adrenergic antagonists) block beta-1 receptors in the heart (reducing heart rate, contractility, and conduction velocity) and beta-2 receptors in the lungs and vasculature. Common beta-blockers include metoprolol (Lopressor), atenolol (Tenormin), and propranolol (Inderal). Selective beta-1 blockers (metoprolol, atenolol) primarily affect the heart with less bronchospasm risk. Nursing considerations: monitor heart rate before administration (hold if HR <60 bpm per protocol), monitor blood pressure, do not discontinue abruptly (risk of rebound tachycardia and hypertension), caution in asthma/COPD patients, and monitor for signs of heart failure.
Question 3: An adverse effect of opioid analgesics that requires monitoring is:
- Hypertension
- Respiratory depression (Correct answer)
- Tachycardia
- Hyperglycemia
Correct answer: Respiratory depression
Respiratory depression is the most dangerous adverse effect of opioid medications and requires ongoing monitoring of respiratory rate and depth.
Opioids (morphine, hydromorphone, fentanyl, oxycodone) act on mu receptors in the CNS to provide analgesia but also depress the respiratory center in the medulla oblongata. Risk factors for opioid-induced respiratory depression include opioid-naive patients, elderly, renal/hepatic impairment, concurrent CNS depressants (benzodiazepines, alcohol), sleep apnea, and high doses. Monitoring includes: respiratory rate (hold if <12/min), oxygen saturation, level of sedation (sedation often precedes respiratory depression), and pain scores. Naloxone (Narcan) is the reversal agent—it competitively blocks opioid receptors. Other common opioid side effects include constipation, nausea, sedation, pruritus, and urinary retention.
Question 4: Antibiotics should ideally be administered:
- Only when the patient feels unwell
- At evenly spaced intervals to maintain consistent blood levels (Correct answer)
- All at once in the morning for convenience
- Only on an empty stomach regardless of type
Correct answer: At evenly spaced intervals to maintain consistent blood levels
Antibiotics should be given at evenly spaced intervals (e.g., every 6 hours for QID) to maintain consistent therapeutic blood levels.
Maintaining consistent antibiotic blood levels above the minimum inhibitory concentration (MIC) is essential for effective bacterial killing and preventing resistance. For example, an antibiotic ordered every 8 hours should be given at 0600, 1400, and 2200—not 0800, 1200, and 1700. Time-dependent antibiotics (penicillins, cephalosporins) require blood levels above MIC for a specific percentage of the dosing interval. Concentration-dependent antibiotics (aminoglycosides, fluoroquinolones) require high peak levels. Medical technicians must administer antibiotics within 30 minutes of the scheduled time and document the actual administration time. Patient education should emphasize completing the full course even if symptoms improve.
Question 5: The term 'drug interaction' refers to:
- A patient's allergic response to a drug
- The effect one drug has on the action of another drug when taken concurrently (Correct answer)
- The manufacturing process of combining drugs
- A medication's expiration date
Correct answer: The effect one drug has on the action of another drug when taken concurrently
Drug interactions occur when one medication alters the effect of another, potentially increasing toxicity or decreasing efficacy.
Drug interactions are classified as: Pharmacokinetic (one drug affects the absorption, distribution, metabolism, or elimination of another—e.g., grapefruit juice inhibiting CYP3A4 enzymes, increasing statin levels) and Pharmacodynamic (drugs with similar or opposing effects—e.g., combining two CNS depressants increases sedation risk). Interactions can be synergistic (enhanced effect), antagonistic (reduced effect), or potentiating (one drug amplifies another's toxicity). Drug-food interactions are also significant (warfarin + vitamin K, MAOIs + tyramine). Medical technicians should check for interactions before administration, monitor for unexpected responses, and report concerns to the pharmacist or prescriber.
Question 6: Which medication class requires monitoring of blood potassium levels?
- Acetaminophen
- Loop diuretics (Correct answer)
- Topical antibiotics
- Antacids
Correct answer: Loop diuretics
Loop diuretics (furosemide, bumetanide) cause potassium excretion in the urine, requiring regular monitoring of serum potassium levels.
Loop diuretics (furosemide/Lasix, bumetanide/Bumex, torsemide) inhibit sodium-potassium-chloride cotransporters in the Loop of Henle, causing excretion of sodium, potassium, chloride, calcium, and magnesium along with water. Hypokalemia (K+ <3.5 mEq/L) is a serious risk because potassium is critical for cardiac conduction. Symptoms of hypokalemia include muscle weakness, fatigue, leg cramps, cardiac arrhythmias, and ECG changes (flattened T waves, U waves). Monitoring includes: daily weights, strict I&O, serum electrolytes (especially potassium, sodium, magnesium), BUN/creatinine, and orthostatic vital signs. Potassium supplements or potassium-sparing diuretics may be prescribed concurrently.
CMT Pharmacology and Medication Actions 2
A medication's 'half-life' refers to: