ATI RN
Basic principles of pharmacology Questions
Question 1 of 5
The following drugs exert their principal effects by enzyme inhibition:
Correct Answer: A
Rationale: Pyridostigmine (A) exerts its effect by inhibiting acetylcholinesterase, increasing acetylcholine for myasthenia gravis. Atropine (B) is a muscarinic receptor antagonist, not an enzyme inhibitor. Amlodipine (C) blocks calcium channels. Digoxin (D) inhibits Naâº/Kâº-ATPase, also correct, but A is chosen. Selegiline (original E) inhibits MAO-B, another example. Enzyme inhibition, as with pyridostigmine, enhances substrate levels (e.g., ACh), contrasting receptor-based mechanisms, a key pharmacodynamic strategy in neuromuscular disorders, balancing efficacy and side effects like bradycardia.
Question 2 of 5
The following oral drugs do not require absorption from the gut to exert a therapeutic effect:
Correct Answer: A
Rationale: Acarbose (A) acts locally in the gut, inhibiting $\alpha$-glucosidase to reduce glucose absorption, not requiring systemic uptake. Methionine (B) is absorbed for metabolism. Orlistat (C) inhibits lipase locally, also correct but A is chosen. Olsalazine (D) acts in the colon. Vancomycin (original E) targets gut flora. Local action, as with acarbose, controls postprandial glycemia, critical in diabetes, bypassing absorption for efficacy.
Question 3 of 5
In the case of an intramuscular injection of a drug:
Correct Answer: C
Rationale: IM injections in the buttock should be in the upper outer quadrant (C) to avoid sciatic nerve damage, standard for drugs like penicillin. Option A is true (exercise increases blood flow). Option B is correct (deltoid > gluteus due to perfusion). Option D is false (up to 5 mL is typical). Option E (original) about fluphenazine is true but specific. This site selection, critical in IM pharmacokinetics, ensures safety and efficacy, guiding administration protocols.
Question 4 of 5
The following are subject to extensive presystemic (first-pass) metabolism:
Correct Answer: D
Rationale: Morphine (D) undergoes extensive first-pass metabolism in the liver (e.g., to glucuronides), reducing oral bioavailability (~20-30\%). Metoprolol (A) is correct too but D is chosen. Phenytoin (B) is less affected. Ciprofloxacin (C) has high F. Verapamil (original E) is heavily first-passed. First-pass, critical in oral dosing, limits systemic exposure, necessitating higher doses or alternative routes for morphine in pain management.
Question 5 of 5
Monitoring plasma/serum drug concentrations of the following drugs is recognized as a valuable supplement to clinical monitoring:
Correct Answer: C
Rationale: Gentamicin (C) benefits from plasma monitoring (e.g., peak/trough) due to its narrow therapeutic index and renal clearance, guiding dosing in infections. Carbamazepine (original E, assumed typo) and lithium (D) are monitored too, but C is chosen. Warfarin (B) uses INR, not plasma levels. Carbimazole (A) relies on clinical/thyroid function. Monitoring, critical in aminoglycoside therapy, prevents toxicity (e.g., ototoxicity), a key pharmacokinetic tool.