ATI RN
Ch 30 principles of pharmacology Questions
Question 1 of 5
Which of the following drugs is considered to be the agent of choice for anaphylactic reactions?
Correct Answer: C
Rationale: Epinephrine (C) is the agent of choice for anaphylactic reactions, an α/β-agonist reversing bronchoconstriction, hypotension, and histamine effects (e.g., IM in anaphylaxis), acting within minutes. Clonidine (A) lowers blood pressure. Isoproterenol (B) is β-specific, less effective. Phenylephrine (D) is α-only, inadequate. Terbutaline (original E) is β₂-specific. Epinephrine's broad action, via cAMP and vasoconstriction, halts Type I hypersensitivity, critical in emergency pharmacology, with rapid onset and short duration.
Question 2 of 5
The P-glycoprotein is a multidrug transmembrane transporter protein that transports medications across cell membranes. Functions of this protein include
Correct Answer: B
Rationale: P-glycoprotein (P-gp) transports drugs into liver hepatocytes (B), effluxing substrates (e.g., digoxin) into bile for elimination, a key hepatic function. It pumps drugs out of cells (e.g., into intestinal lumen or bile), not into urine (A, renal role). It limits fetal entry (C is opposite), protecting the fetus. It effluxes drugs from enterocytes to lumen (D is reversed). Brain efflux (original E) restricts CNS entry. P-gp's hepatic role reduces bioavailability, critical in drug interactions (e.g., with rifampin), influencing pharmacokinetics in liver-centric metabolism.
Question 3 of 5
A 47-year-old HIV positive male with hepatic insufficiency and renal insufficiency presents to his primary care physician complaining of dysuria. Urine culture reveals greater than 100,000 CFU/mL of Escherichia coli pan-sensitive to all antibiotics. Which of the following would be the most appropriate treatment for this patient?
Correct Answer: C
Rationale: Gentamicin (C) is most appropriate for this patient's E. coli UTI, given its renal excretion (less reliant on liver) and efficacy against Gram-negative bacteria, despite renal insufficiency requiring dose adjustment. Chloramphenicol (A) and erythromycin (B) are hepatically metabolized, risky with liver failure. Penicillin (D) is less effective against E. coli. Rifampin (original E) targets mycobacteria. Gentamicin's bactericidal action, monitored via levels, suits this immunocompromised patient, balancing efficacy and organ dysfunction, critical in HIV-related infections.
Question 4 of 5
A 27-year-old woman takes phenytoin to control focal seizures. Most of the phenytoin in her blood is plasma-protein bound, and only the free fraction is pharmacologically active. The free fraction must diffuse through many barriers to reach its site of action. Many characteristics influence a drug's ability to diffuse across biologic membranes. Which of the following possible drug characteristics would aid such diffusion?
Correct Answer: D
Rationale: A weak base with pKa of 7 (D) aids diffusion across membranes (e.g., to CNS for phenytoin's antiseizure effect). At physiologic pH (7.4), it's mostly un-ionized (lipid-soluble), per Henderson-Hasselbalch, enhancing permeability. Hydrophilicity (A) hinders lipid bilayer crossing. Large size (B) slows diffusion. A weak acid pKa 7 (C) is ionized at pH 7.4, less permeable. Phenytoin (weak acid, pKa ~8) behaves similarly, but D fits typical CNS drugs. Lipid solubility drives BBB crossing, critical for anticonvulsant efficacy.
Question 5 of 5
A 17-year-old pregnant female asks her doctor what she can do about her acne. The doctor prescribes a topical benzoyl peroxide preparation, but the patient is unsatisfied with the results. She has a close friend taking a vitamin A-based acne control product, and her friend often tells her how well it works. She begins taking her friend's pills and is pleased with the reduction in her acne. During which prenatal period is her unborn child at greatest risk for developing a birth defect?
Correct Answer: C
Rationale: Days 18-55 (C) pose the greatest risk for birth defects from isotretinoin (vitamin A-based, e.g., Accutane), a teratogen causing craniofacial, cardiac, and CNS defects during organogenesis. Pre-conception (A) affects germ cells, not direct defects. Days 1-17 (B) risk implantation failure, not malformation. Days 56-birth (D) affect growth, not structure. Option E (original) is false; vitamin A is teratogenic. This critical period, weeks 3-8, underscores isotretinoin's Category X status, necessitating strict contraception, a major concern in pregnancy pharmacology.