Practive questions before TBL on pharm

An 18-year-old female patient is brought to the emergency department due to drug overdose. Which of the following routes of administration is the most desirable for administering the antidote for the drug overdose? A. Intramuscular B. Intravenous C. Oral D. Subcutaneous E. Transdermal

B. Intravenous The intravenous route of administration is the most desirable because it results in achievement of therapeutic plasma levels of the antidote rapidly

A 40-year-old male patient (70 kg) was recently diagnosed with infection involving methicillin-resistant S. aureus. He received 2000 mg of vancomycin as an IV loading dose. The peak plasma concentration of vancomycin was 28.5 mg/L. The apparent volume of distribution is: A. 1 L/kg B. 7 L/kg C. 10 L/kg D. 14 L/kg E. 70 L/kg

Correct answer = A. Vd = dose/C = 2000 mg/28.5 mg/L = 70.1 L. Because the patient is 70 kg, the apparent volume of distribution in L/kg will be approximately 1 L/kg (70.1 L/70 kg).

A pharmacokinetic study of a new antihypertensive drug is being conducted in healthy human volunteers. The half-life of the drug after administration by continuous intravenous infusion is 12 hours. Which of the following best approximates the time for the drug to reach steady state? A. 24 hours B. 48 hours C. 72 hours D. 120 hours E. 240 hours

Correct answer = B. A drug will reach steady state in about 4 to 5 half-lives. Therefore, for this drug with a half-life of 12 hours, the approximate time to reach steady state will be 48 hours. (really we say 5 half lives but okay)

KR2250 is an investigational cholesterol-lowering agent. KR2250 has a high molecular weight and is extensively bound to albumin. KR2250 will have a(n) _______________ apparent volume of distribution (Vd). A. High B. Low C. Extremely high D. Normal

Correct answer = B. Because of its high molecular weight and high protein binding, KR2250 will be effectively trapped within the plasma (vascular) compartment and will have a low apparent volume of distribution.

A 68-year-old woman is brought to the emergency department for treatment of a myocardial infarction. She is currently taking clopidogrel (antiplatelet agent and progrug) and aspirin daily, as well as omeprazole (potent CYP inhibitor) for heartburn. Which of the following is the most likely contributor to her myocardial infarction today? A. Reduced antiplatelet activity of clopidogrel due to aspirin B. Reduced antiplatelet activity of clopidogrel due to omeprazole C. Hypersensitivity reaction due to clopidogrel D. Increased antiplatelet activity of clopidogrel due to omeprazole E. Increased antiplatelet activity of clopidogrel due to aspirin

Correct answer = B. Clopidogrel is a prodrug and requires CYP2C19 activity for conversion to an active metabolite. Because omeprazole is a potent CYP inhibitor, clopidogrel is not converted to the active metabolite, and therefore the antiplatelet activity is reduced, potentially contributing to myocardial infarction.

A 74-year-old man was admitted to the hospital for treatment of heart failure. He received 160 mcg of digoxin intravenously, and the plasma digoxin level was 0.4 ng/mL. If the desired plasma concentration of digoxin for optimal therapeutic activity in heart failure is 1.2 ng/mL, and the patient has an estimated Vd of 400 L, calculate the additional dose of digoxin needed for this patient to achieve the desired plasma concentration. A. 128 mcg B. 160 mcg C. 320 mcg D. 480 mcg E. 640 mcg

Correct answer = C. The additional dosage of digoxin needed to achieve the desired plasma concentration can be calculated using the equation Vd (C2 - C1). C1 is the current plasma concentration (0.4 ng/mL) and C2 is the desired plasma concentration (1.2 ng/mL). Therefore, the additional dosage of digoxin is [400 L × (1.2 - 0.4) ng/mL)] = 320 mcg.

Drug A is a weakly basic drug with a pKa of 7.8. If administered orally, at which of the following sites of absorption will the drug be able to readily pass through the membrane? A. Mouth (pH approximately 7.0) B. Stomach (pH of 2.5) C. Duodenum (pH approximately 6.1) D. Jejunum (pH approximately 8.0) E. Ileum (pH approximately 7.0)

Correct answer = D. Because Drug A is a weakly basic drug (pKa = 7.8), it will be predominantly in the nonionized form in the jejunum (pH of 8.0). For weak bases, the nonionized form will permeate through the cell membrane readily.

A 55-year-old woman is brought to the emergency department because of seizures. She has a history of renal disease and currently undergoes dialysis. She receives an intravenous infusion of antiseizure Drug X. Which of the following is likely to be observed with use of Drug X in this patient in terms of the half life and dosing as compared to a normal patient?

Correct answer = D. Because the patient has a renal disorder, she may not be able to excrete the drug effectively. Therefore, the half-life of Drug X will be prolonged. As the half-life is prolonged, the dosage must be reduced so the patient will not have serious toxic effects of Drug X.

A 64-year-old female patient (60 kg) is treated with experimental Drug A for type 2 diabetes. Drug A is available as tablets with an oral bioavailability of 90%. If the Vd is 2 L/kg and the desired steady-state plasma concentration is 3.0 mg/L, which of the following is the most appropriate oral loading dose of Drug A? A. 6 mg B. 6.66 mg C. 108 mg D. 360 mg E. 400 mg

Correct answer = E. For oral dosing, loading dose = [(Vd) × (desired steady-state plasma concentration)/F]. The Vd in this case is corrected to the patient's weight is 120 L. The F value is 0.9 (because bioavailability is 90%, that is, 90/100 = 0.9). Thus, loading dose = (120 L × 3.0 mg/L)/0.9 = 400 mg.

Which of the following reactions represents Phase II of drug metabolism? A. Amidation B. Hydrolysis C. Oxidation D. Reduction E. Sulfation

Correct answer = E. Phase II metabolic reactions involve conjugation reactions to make phase I metabolites more polar.

what are the most common forms of phase II metabolism?

Sulfation and glucuronidation are the most common phase II conjugation reactions.