ATI RN
Basic principles of pharmacology Questions
Question 1 of 5
Which of the following statements concerning a drug receptor is true?
Correct Answer: C
Rationale: A drug receptor can bind endogenous ligands to produce physiological activity (C), e.g., acetylcholine at nicotinic receptors for muscle contraction, a core pharmacodynamic principle. Option A is false; anesthetics act non-specifically on membranes. Option B is incorrect; receptors exist naturally. Option D is wrong; magnesium citrate's cathartic effect is osmotic, not receptor-based. Option E (original) about down-regulation is false; it desensitizes. Receptors' endogenous role enables drug mimicry or blockade, fundamental to therapeutic targeting.
Question 2 of 5
A 31-year-old man is brought to the emergency department complaining of dyspnea. He has a history of asthma and has had multiple asthma attacks requiring intubation for airway maintenance. He is noncompliant with his medications prescribed for this condition. Physical examination reveals a young man in acute distress. His room air oxygen saturation is $87 \%$. In addition to administration of oxygen, immediate drug administration of albuterol should be administered by which of the following routes?
Correct Answer: A
Rationale: Inhalation (A) is the best route for immediate albuterol administration in this asthma attack, delivering the $\beta_2$-agonist directly to bronchial smooth muscle for rapid bronchodilation (within minutes), critical with $87\%$ oxygen saturation. Intranasal (B) targets nasal mucosa, not lungs. Subcutaneous (C) and sublingual (D) are slower, bypassing direct airway delivery. Topical (original E) is irrelevant. Inhalation's speed and specificity (e.g., via nebulizer or MDI) maximize efficacy in acute distress, minimizing systemic effects, essential in emergency asthma management to restore airflow and prevent intubation.
Question 3 of 5
A patient receives a single dose of antibiotics following a prostate needle biopsy. He takes $500 \mathrm{mg}$ of ciprofloxacin immediately after completion of the procedure. The half-life of the medication is $8 \mathrm{~h}$. At approximately how many half-lives will it take for $90 \%$ of the drug to be excreted from the body?
Correct Answer: D
Rationale: It takes ~3.3 half-lives (D) for $90\%$ of ciprofloxacin (tâ‚/â‚‚ = 8 h) to be excreted after a single dose. In first-order kinetics, fraction remaining = (1/2)^n; for $10\%$ remaining (90\% gone), 0.1 = (1/2)^n, n ≈ 3.32 (log-based calculation). Options A (1), B (2), and C (3) leave >10\%; E (5, original) exceeds. Thus, ~26.6 h (3.3 × 8) clears $90\%$, aligning with ciprofloxacin's renal excretion profile, critical for post-procedure prophylaxis to prevent infection without prolonged exposure.
Question 4 of 5
A drug that binds to a receptor and produces a biological response that mimics the response to the endogenous ligand is known as
Correct Answer: A
Rationale: An agonist (A) binds receptors and mimics the endogenous ligand's response (e.g., albuterol mimics epinephrine at $\beta_2$ receptors for bronchodilation). Antagonists (B) block without response. Functional antagonists (C) oppose via different mechanisms. Partial agonists (D) and antagonists (original E) produce submaximal effects or block partially. Agonists' full activation, critical in pharmacodynamics, drives therapeutic effects, distinguishing them from blockers or partial stimulators in receptor theory.
Question 5 of 5
A 16-year-old male high school football player takes $800 \mathrm{mg}$ of ibuprofen after morning practice for a sore knee. Ibuprofen has a half-life of about $2 \mathrm{~h}$. What percentage of the original plasma load of ibuprofen will remain in his blood when afternoon practice starts in $4 \mathrm{~h}$ ?
Correct Answer: C
Rationale: $25\%$ (C) of ibuprofen remains after 4 h (tâ‚/â‚‚ = 2 h). In first-order kinetics, fraction remaining = (1/2)^(t/tâ‚/â‚‚) = (1/2)^(4/2) = (1/2)^2 = 0.25 = $25\%$. Options A (0\%) requires >5 half-lives, B (12.5\%) is 3 half-lives, D (50\%) is 1 half-life, E (75\%, original) underestimates decay. After 4 h (~2 half-lives), $200 \, \text{mg}$ remains from $800 \, \text{mg}$, aligning with ibuprofen's rapid clearance, relevant for timing pain relief in active patients.