Kinetics Practice Problems PDF

1. CK Mann needs to be treated with a drug that is primarily eliminated by glomerular filtration. His creatinine clearance has deteriorated to 20 mL/minute. The normal schedule for the treatment drug is 300 mg q 6 h. from a nomogram, the ratio of elimination rate constant in uremia to normal kU/kN =...

1. CK Mann needs to be treated with a drug that is primarily eliminated by glomerular filtration. His creatinine clearance has deteriorated to 20 mL/minute. The normal schedule for the treatment drug is 300 mg q 6 h. from a nomogram, the ratio of elimination rate constant in uremia to normal kU/kN = 60%. What does of drug should be given q 6 h? - a. 420 mg - b. 250 mg - c. 180 mg - d. 150 mg 2. **CASE:** joe blow was given an IV bolus dose of 900 mg of the drug GETAFIX. GETAFIX follows first order (i.e. linear) two compartment pharmacokinetics. After a successful analysis of the plasma drug concentration data at various times using the Method of Residuals, values of A, B, a, and b were determined to be 7 mg/L, 3.25 mg/L, 2.12 h^-1, and 0.04 hr^-1 respectively. **QUESTION 4 OF 4:** What is the plasma level of the drug 5 hours after the administration of GETAFIX? - a. 3.25 mg/L - b. 2.52 mg/L - c. 2.66 mg/L - d. 3.84 mg/L 3. **CASE:** joe blow was given an IV bolus dose of 900 mg of the drug GETAFIX. GETAFIX follows first order (i.e. linear) two compartment pharmacokinetics. After a successful analysis of the plasma drug concentration data at various times using the Method of Residuals, values of A, B, a, and b were determined to be 7 mg/L, 3.25 mg/L, 2.12 h^-1, and 0.04 hr^-1 respectively. **QUESTION 3 OF 4:** Calculate k21. - a. 2.10 hr^-1 - b. 0.7 hr^-1 - c. 4.76 hr^-1 - d. 0.12 hr^-1 4. **CASE:** joe blow was given an IV bolus dose of 900 mg of the drug GETAFIX. GETAFIX follows first order (i.e. linear) two compartment pharmacokinetics. After a successful analysis of the plasma drug concentration data at various times using the Method of Residuals, values of A, B, a, and b were determined to be 7 mg/L, 3.25 mg/L, 2.12 h^-1, and 0.04 hr^-1 respectively. **QUESTION 1 OF 4:** Calculate k. - a. 1.3 hr^-1 - b. 0.54 hr^-1 - c. 0.06 hr^-1 - d. 0.12 hr^-1 5. **CASE:** joe blow was given an IV bolus dose of 900 mg of the drug GETAFIX. GETAFIX follows first order (i.e. linear) two compartment pharmacokinetics. After a successful analysis of the plasma drug concentration data at various times using the Method of Residuals, values of A, B, a, and b were determined to be 7 mg/L, 3.25 mg/L, 2.12 h^-1, and 0.04 hr^-1 respectively. **QUESTION 2 OF 4:** Calculate k12. - a. 0.41 hr^-1 - b. 0.1 hr^-1 - c. 0.7 hr^-1 - d. 1.34 hr^-1 6. The figure below is a Scatchard plot of the drug RESAHC and depicts its binding to its target, which of the following statements is/are most likely to be true? - a. RESAHC fits a two-compartment pharmacokinetic model - b. None of the above - c. RESAHC has more than one unique binding site on each molecule of target protein - d. RESAHC binds poorly to its target protein 7. Following five half-lives after initiation of a multi-dose schedule of an antibiotic drug for patient PJ, serum drug concentrations were determined to be 25 mg/L rather than the expected 20 mg/L. Assuming linear pharmacokinetics, which of the following influences are plausible? - a. The antibiotic is a prodrug - b. The antibiotic binds less to plasma protein than anticipated - c. PJ is using less of the antibiotic than instructed - d. Metabolizing enzymes are less active than anticipated 8. **CASE:** the equation that best describes the pharmacokinetics of KUMBACT in Mr. Zbigniew is: * $C_p = 50(e^{-0.19t} - e^{-1.4t})$ * $K = -0.19$ * $K_a = -1.4$ Where $C_p$ is the plasma KUMBACT concentration at time t hours following a single oral dose of 250 mg. **QUESTION 2 OF 2:** answer based on the attached case, using a relevant equation in the attachment: what is the maximum plasma concentration of KUMBACT? - a. 19.8 mg/L - b. 33.5 mg/L - c. 31.6 mg/L 9. **CASE:** the equation that best describes the pharmacokinetics of KUMBACT in Mr. Zbigniew is: * $C_p = 50(e^{-0.19t} - e^{-1.4t})$ Where $C_p$ is the plasma KUMBACT concentration at time t hours following a single oral dose of 250 mg. **QUESTION 1 OF 2:** answer based on the attached case, using a relevant equation in the attachment: what is the elimination half-life of KUMBACT in Mr. Zbigniew? - a. 1.4 hours - b. 0.16 hours - c. 4.3 hours - d. 3.65 hours - e. 0.46 hours 10. Which of the following is NOT a way to extend the release of a drug from a solid oral formulation product? - a. Erosion - b. Leaching - c. Mulching - d. Osmosis 11. **CASE:** JD is a 45-year-old female being treated for an infection. She weighs 105 kg and has a height of 5 ft 6 inches (167.64 cm). her serum creatinine level has been determined to be 0.7 mg/dL. **QUESTION 3 of 3:** estimate JD's creatinine clearance. - a. 168 mL/minute - b. 81 mL/minute - c. 102 mL/minute - d. 112 mL/minute - e. 95 mL/minute 12. **CASE:** Ms. Claire Maynard, a 40-year-old 76 kg woman was given 6mg/kg/day of phenytoin sodium for a month. At that point, the average plasma concentration was determined to be 10 mg/L. Michaelis constant = 4 mg/L ; salt factor = 0.92 ; fraction of dose absorbed = 1 **QUESTION 1 of 2:** determine the maximum rate of phenytoin elimination from Ms. Maynard. - a. 160 mg/day - b. 604.8 mg/day - c. 587.3 mg/day - d. 7.7 mg/day 13. **CASE:** Ms. Claire Maynard, a 40-year-old 76 kg woman was given 6mg/kg/day of phenytoin sodium for a month. At that point, the average plasma concentration was determined to be 10 mg/L. Michaelis constant = 4 mg/L ; salt factor = 0.92 ; fraction of dose absorbed = 1 **QUESTION 2 of 2:** as a steady-state plasma concentration of 10 mg/L would be sub-therapeutic, what dosing rate would be necessary to achieve a steady-state plasma concentration of 15 mg/L? - a. 477.5 mg/day - b. 440 mg/day - c. 504 mg/day - d. 6.6 mg/day 14. **CASE:** JD is a 45-year-old female being treated for an infection. She weighs 105 kg and has a height of 5 ft 6 inches (167.64 cm). her serum creatinine level has been determined to be 0.7 mg/dL. **QUESTION 2 of 3:** what is JD's ideal body weight? - a. 54.2 kg - b. 63.8 kg - c. 50.4 kg - d. 59.3 kg 15. SETANDRAG has a therapeutic range of 1 to 6 mg/mL. If the desired steady-state level is 3 mg/mL, what dose of SETANDRAG, given every 8 hours, will achieve this in an 80 kg individual? (Apparent volume of distribution is 33.5% of body weight; elimination half-life is 2 hours; F = 1, S = 1). - a. 2 mg - b. 186 mg - c. 223 mg - d. 149 mg - e. 19 mg 16. Lozenges are exempt from USP disintegration specifications. - a. True - b. False 17. The interaction between tetracycline and foods containing polyvalent cations or antacids results in which of the following? - a. Increased gastric emptying - b. Increased gastric motility - c. Increased tetracycline absorption - d. Decreased tetracycline absorption 18. Modified-release products do NOT: - a. Allow for two-fold or more reduction in frequency of drug dosing - b. Allow for the release of (a) portion(s) of drug on a delayed basis - c. Allow for elimination of (a) portion(s) of drug on a delayed basis directly - d. Allow for the release of (a) portion(s) of drug at a physiologic site 19. Michaelis-Menten pharmacokinetics is the only source of non-linearity in drug absorption. - a. True - b. False 20. Data from non-physiologically based compartment pharmacokinetic models in non-humans may be used to extrapolate expectations in humans. - a. True - b. False 21. **CASE QUESTION:** the area under the plasma concentration-time plot (AUC) calculated after an oral FIXIT tablet of 150 mg of a given drug was 800 mg.hr/L. After an oral capsule dose of 150 mg of the same drug, the calculated AUC was 640 mg.hr/L. The absolute bioavailability of the FIXIT oral tablet was calculated to be 0.98. **QUESTION 2 OF 2:** calculate the absolute bioavailability of the capsule form of FIXIT. - a. 0.91 - b. 1.05 - c. 1.10 - d. 0.80 22. The total clearance of a maintenance drug for a cardiovascular ailment is 620 mL/min in young adults and 300 mL/min in octogenarians. KC is an octogenarian who should begin maintenance therapy using this drug. The typical maintenance dose is 5 mg daily in young adults. Assuming the same dose, interval between doses and bioavailability with no adjustments, by how much would the average steady-state plasma concentration in KC be higher than that in a young adult patient? - a. 12.5 - b. 0.4 - c. 2.1 - d. 6 - e. 2.5 23. **CASE:** Drug A has an elimination half-life of 24 hours. Drug B has an elimination half-life of 2 hours. **QUESTION 2 of 3:** More Drug A would be required for a formulation with a 48-hour duration of release than Drug B. - a. True - b. False 24. Anesthesiologist Sam Hemans wants to reach a plasma level of 11 ug/mL of a general anesthetic immediately. In trying to achieve this by way of a simultaneous IV infusion (1.5 mg/hours) and a loading IV dose, what loading dose would you recommend? (First order elimination half-life of the general anesthetic is 7 hours; volume of distribution (one compartment) of the general anesthetic is 20 L). - a. 70 mg - b. 10 mg - c. 15 mg - d. 20 mg 25. An anti-arrythmic drug has been formulated into two oral solid products of identical drug strength: A and B. - Product A contains 4% granulating agent; 1% disintegrating agent; 3% lubricant - Product B contains 4% granulating agent; 1% disintegrating agent; 1% lubricant Which of the following statement is likely true after administration of a single dose of each product? - a. Product A will have a arrive at maximum plasma concentration sooner - b. Product B will have the lower maximum plasma concentration - c. Product B will have a arrive at maximum plasma concentration later - d. Product A will have the lower maximum plasma concentration 26. **CASE:** Drug A has an elimination half-life of 24 hours. Drug B has an elimination half-life of 2 hours. **QUESTION 3 of 3:** More Drug B is needed for release over a 6-hour period than over a 16-hour period. - a. True - b. False 27. Inclusion of polyethylene glycol in the constitution of liposomes - a. Enables them to evade phagocytes - b. Increases the volume of distribution of some drugs - c. Decreases the elimination half-life of some drugs - d. Retards their function 28. An antagonist - a. Binds to a receptor, activating it partially - b. Does not bind to a receptor - c. Binds to a receptor, activating it maximally - d. Binds to a receptor without activating it 29. Which of the following statement is TRUE? - a. Suspending agents in liquid oral formulations facilitate absorption - b. Suspending agents in liquid oral formulations retard absorption - c. Suspending agents facilitate disintegration - d. Suspending agents are destabilizing 30. Unlike yesterday when she took her oral dose with water, Kate Johnson has taken her latest daily dose of SIMVASTATIN with grapefruit juice. Her plasma concentration of the drug will be lower than that taken the previous day. - a. True - b. False 31. The drug SWYITDRAG has a molecular weight 480, and is highly plasma protein-bound. In the kidney: - a. SWYITDRAG cannot be filtered in the glomerulus - b. SWYITDRAG cannot be excreted by the kidneys - c. SWYITDRAG cannot be re-absorbed in the distal tubules - d. SWYITDRAG cannot be actively secreted in the proximal convoluted tubule or loop of Henle 32. Which phase of metabolism are ATP Binding Cassette transporters involved in? - a. Phase III - b. Phase I - c. Phase II 33. A drug administered orally is less likely to be secreted in the bile than when intravenously administered. - a. True - b. False 34. SUPADRAG has a low fraction unbound in the tissues. This suggests: - a. No insights regarding the apparent volume of distribution - b. It has a high apparent volume of distribution - c. It has a low apparent volume of distribution 35. Therapeutic concentration of the POTENTDRUG range between 0.05 ng/L and 0.15 ng/L. The Michaelis constant of POTENTDRUG is 1.5 mg/L. which of the following would be true? - a. The metabolism of POTENTDRUG is via saturation pharmacokinetics - b. The distribution of POTENTDRUG is via saturation pharmacokinetics - c. The rate of metabolism of POTENTDRUG is proportional to its concentration in the blood - d. The toxicity threshold of POTENTDRUG is high 36. For a prodrug, pharmacologic activity will decrease during liver disease. - a. True - b. False 37. Twins Amy and Irma have both been on an identical multiple once-daily oral dose regimen of the drug GUDHART. Both have adhered to the dosing instructions except that Amy missed a dose five days ago, Irma missed a dose yesterday. Assuming GUDHART has similar absorption, distribution, and elimination properties in both women: - a. GUDHART blood concentrations should be similar in both women - b. Amy should have a higher blood concentration of GUDHART than Irma - c. Irma should have a higher blood concentration of GUDHART than Amy 38. Antibodies are useful as biopharmaceutical primarily because - a. They are highly specific - b. They are highly lipophilic - c. They are highly hydrophilic - d. They have high molecular weights 39. A drug was given by multiple doses of 150 mg every 6 hr to Joe Blow (42 years old and 63.1 kg). assume a one compartment linear model applies to this drug in this concentration range. For this dosage form and patient the bioavailability was 0.67 and the absorption rate constant was 3.21 hr^-1. For this drug, the first order elimination rate constant and apparent volume of distribution in Joe Blow were 0.155 hr^-1 and 0.53 L/kg, respectively. Calculate the average drug concentration in Joe Blow at steady state. - a. 77.5 mg/L - b. 135.5 mg/L - c. 90 mg/L - d. 3.23 mg/L 40. Following the taking of an oral dose a drug by a patient, samples were drawn at regular intervals and assayed. From the plot of the plasma drug concentration versus time: - a. Bioavailability is not discernible from such a plot - b. The area-under-the-curve is a measure of the rate of absorption - c. The maximum plasma concentration is a measure for the extent of absorption 41. **CASE QUESTION:** the area under the plasma concentration-time plot (AUC) calculated after an oral FIXIT tablet of 150 mg of a given drug was 800 mg.hr/L. After an oral capsule dose of 150 mg of the same drug, the calculated AUC was 640 mg.hr/L. The absolute bioavailability of the FIXIT oral tablet was calculated to be 0.98. **QUESTION 1 OF 2:** calculate the relative bioavailability of the FIXIT tablet with respect to the capsule. - a. 161.54 - b. 0.58 - c. 1.23 - d. 0.93 - e. 1.08 42. **CASE:** Drug A has an elimination half-life of 24 hours. Drug B has an elimination half-life of 2 hours. **QUESTION 1 of 3:** Drug A is a better candidate for formulation into an oral modified-release product than product B. - a. True - b. False 43. Which of the following best describes drug dissolution? - a. Henderson-Hasselbalch - b. Michaelis-Menten - c. Noyes-Whitney - d. Fick's Law 44. A methyl xanthine drug follows first order kinetics and has an elimination half-life of 6 hours. If the clearance of this drug is attributable to the kidneys and liver only, what is the metabolism rate constant? (the drug has a volume distribution of 35 L, and a renal clearance of 0.36 L/hour). - a. 0.32/hour - b. 0.09/hour - c. 13.9/hour - d. 0.11/hour - e. 10.8/hour 45. Which of the following is TRUE concerning orders of pharmacokinetics processes? - a. If the amount of a drug decreases by a constant amount in a constant time interval, the process is first order - b. For most drugs, the overall rate of elimination follows zero order kinetics - c. If the drug amount decreases in proportion to the amount of drug remaining, the process is zero order - d. For most drugs, the overall rate of elimination follows first order kinetics 46. Regarding the metabolic reaction involving a metabolizing enzyme and its substrate drug, the Lineweaver-Burk equation is NOT a suitable approach to determine the maximum rate of the reaction. - a. True - b. False 47. Drug A has intrinsic clearance 1800 mL/min. Drug B has intrinsic clearance 25 mL/min. which of the two drugs is likely to show the greatest increase in hepatic clearance if hepatic blood flow increases by 50%? - a. Neither drug A nor B - b. Drug A - c. Drug B 48. Which of the following will double the duration of pharmacologic response following the administration of an i.v. bolus dose of a drug? - a. Doubling the dose - b. Doubling the elimination half-life - c. Doubling the elimination rate constant - d. Doubling the apparent volume of distribution 49. Hysteresis is overcome - a. When only free drug in a pharmacodynamics compartment is used - b. When only free drug in pharmacokinetics compartment is used - c. Through the use of anxiolytics and counseling - d. Through the use of lower doses