ATI RN
Basic pharmacology principles Questions
Question 1 of 5
A 28-year-old man with seborrheic dermatitis is prescribed a topical corticosteroid crème by his dermatologist in hopes of alleviating the chronic rash and erythema on the cheeks. Which of the following steps is most critical to achieve a therapeutic drug concentration in plasma?
Correct Answer: A
Rationale: Absorption (A) is most critical to achieve a therapeutic plasma concentration for a topical corticosteroid. Applied to the skin, the drug must penetrate the stratum corneum to reach dermal blood vessels for systemic uptake (e.g., hydrocortisone for inflammation). Distribution (B) occurs post-absorption, spreading drug to tissues. Elimination (C) removes it, reducing levels. Glycosylation (D) and metabolism (original E) are irrelevant to initial plasma entry. Poor absorption (e.g., due to thick skin or low lipid solubility) limits systemic levels, critical for efficacy in seborrheic dermatitis if systemic effects are needed, though topical drugs primarily act locally, with plasma levels as a secondary outcome.
Question 2 of 5
A medical student is doing a summer research project studying five antibiotics to determine potency using the EC50. Antibiotics are placed in plated culture wells with 100,000 CFU of Escherichia coli. The EC50 results for the five antibiotics are shown in the following choices. Based on the results, the most potent antibiotic is
Correct Answer: B
Rationale: Antibiotic B (EC50 = 2) (B) is the most potent, as potency is inversely related to EC50:the lowest dose achieving 50\% effect (e.g., E. coli kill). Options A (100), C (80), and D (20) require higher doses; E (50, original) is intermediate. B's low EC50 indicates greater receptor affinity or efficacy per unit dose, critical in antibiotic selection, where potency guides efficacy against pathogens, though clinical use also weighs spectrum and resistance, making B superior in this lab context.
Question 3 of 5
A 15-year-old boy who has diabetes and is insulin dependent is brought to the emergency department after collapsing at a baseball game. His blood sugar is $463 \mathrm{mg} / \mathrm{dL}$ by finger stick. Which of the following routes of administration would be most efficacious for medications to bring the blood sugar down?
Correct Answer: B
Rationale: Intravenous (B) is most efficacious for insulin in this hyperglycemic crisis (463 mg/dL), delivering it directly to the bloodstream for rapid glucose uptake (within minutes), critical in diabetic ketoacidosis. Intramuscular (A) and subcutaneous (D) are slower (15-30 min onset). Oral (C) isn't viable for insulin (degraded by GI). Sublingual (original E) is impractical. IV's immediacy, bypassing absorption delays, ensures fast correction, vital in emergencies to prevent organ damage, a cornerstone of acute diabetes management.
Question 4 of 5
A 19-year-old female has a history of absence seizures. She currently takes ethosuximide to control her symptoms. The process of eliminating this drug involves multiple steps of metabolism followed by excretion. Many organs take part in both metabolism as well as excretion of drugs. Which of the following describes a step of metabolism?
Correct Answer: A
Rationale: Acetaminophen glucuronidation by enterocytes (A) is a metabolic step, a phase II reaction conjugating the drug for excretion, occurring in gut and liver. Digoxin transport (B) and pancuronium filtration (D) are excretion, not metabolism. Ethanol exhalation (C) is elimination via lungs, not transformation. Ethosuximide's hepatic metabolism (e.g., hydroxylation) parallels this, with enterocyte glucuronidation enhancing polarity, critical for clearance, distinguishing metabolism from mere transport in pharmacokinetics.
Question 5 of 5
A 21-year-old man presents to his primary care physician complaining of a single, painless ulcer on his penis, which he first noticed a few days ago. He admits to multiple sexual partners. You want to treat him for syphilis with penicillin G, but his history includes an itchy rash following amoxicillin treatment as a child. What must first occur in the body for a penicillin to become allergenic?
Correct Answer: B
Rationale: Penicillin becomes allergenic by binding to a larger molecule (e.g., proteins) (B), forming a hapten-carrier complex the immune system recognizes as foreign, triggering IgE-mediated Type I hypersensitivity (e.g., rash). First-pass metabolism (A) isn't required. Simple exposure (C) needs sensitization first. Option D is false; penicillin's allergenicity is IgE-driven. This conjugation, critical in syphilis treatment (penicillin G), necessitates allergy screening, as prior amoxicillin reaction suggests risk, guiding alternative therapy (e.g., doxycycline).