Question: A Pharmacokinetics Study On Po Dosing A 75 Mg Dose Of A Drug Was Administered As An Oral Solution To Nine Healthy Volunteers. Plasma Samples Were Collected At Various Times After Administration And Were Analyzed For The Parent Drug. After At Least 10 Elimination Half-lives, The Study Was Repeated With 75-mg Oral Tablets. A Pharmacist Plotted The Plasma …

A pharmacokinetics study on Po dosing A 75 mg dose of a drug was administered as an oral solution to nine healthy volunteers. Plasma samples were collected at various times after administration and were analyzed for the parent drug. After at least 10 elimination half-lives, the study was repeated with 75-mg oral tablets. A pharmacist plotted the plasma concentration vs. time curves in both linear scale and semilog scale as shown below 16 1.4 Oral solution 12 1 Plasma concentration (m) 08 0.4 02 0 0 5 10 25 30 Time tours) 20 1 -Oral solution 0.5 0 0 15 20 25 30 LN (plasma concentration) -0.5 -15 -2 Time The pharmacist then determined the best-fit equation for the elimination phase as below: For oral solution: InCp -0.101 +1.0315 For oral tablets: InCp = -0.0996t+0.6791 The pharmacist decided to use the feathering method to determine the absorption rate constant and obtained the following equations: For oral solution: Incidiff) – 0.5155t +1.0956 For oral tablets: InC(diff) = -0.4992 +0.8365 Please answer the following questions: 1. What are the elimination rate constants of the drug that the pharmacist calculated using the oral solution and oral tablets? Is there any significant difference the two? 2. What are the absorption rate constant of the drug that the pharmacist calculated suing the oral solution and oral tablets? Is there any significant difference between the two? 3. Why are the intercepts of the equations for the elimination phase different for oral solution and oral tablets (1.0315 vs. 0.6791)? 4. Calculate tmax for both oral solution and oral tablets and compare with that observed on the plasma concentration vs. time graph. Use the average of the elimination and absorption rate constants from the oral solution and oral tablets. 5. Calculate the Cmax for both the oral solution and oral tablets 6. Does the drug exhibit flip-flop kinetics? 7. Why is the tmax for the oral tablets longer than that for the oral solution? 8. What is the plasma concentration 8 hours after administration of the oral solution and oral tablets? 9. How long does it take for the drug to be completely absorbed and eliminated? A pharmacokinetics study on PO dosing A 75-mg dose of a drug was administered as an oral solution to nine healthy volunteers. Plasma samples were collected at various times after administration and were analyzed for the parent drug. After at least 10 elimination half-lives, the study was repeated with 75-mg oral tablets. A pharmacist plotted the plasma concentration vs. time curves in both linear scale and semilog scale as shown below. 1.6 1.4 Oral solution 12 1 Plasma concentration (mg/l) 0.8 0.6 0.4 0.2 0 5 20 Time tours 1 Oral solution 05 0 Od 15 20 25 8 LN (plasma concentration) 3-15 -2 Time The pharmacist then determined the best-fit equation for the elimination phase as below. For oral solution: InCp = -0.101t+1.0315 For oral tablets: InCp = -0.09967 + 0.6791 The pharmacist decided to use the feathering method to determine the absorption rate constant and obtained the following equations: For oral solution: Inc(diff) = -0.5155 +1.0956 For oral tablets: InC{diff) = -0.4992t +0.8365 Please answer the following questions: 1. What are the elimination rate constants of the drug that the pharmacist calculated using the oral solution and oral tablets? Is there any significant difference the two? 2. What are the absorption rate constant of the drug that the pharmacist calculated suing the oral solution and oral tablets? Is there any significant difference between the two? 3. Why are the intercepts of the equations for the elimination phase different for oral solution and oral tablets (1.0315 vs. 0.6791)? 4. Calculate tmax for both oral solution and oral tablets and compare with that observed on the plasma concentration vs. time graph. Use the average of the elimination and absorption rate constants from the oral solution and oral tablets. 5. Calculate the Cmax for both the oral solution and oral tablets 6. Does the drug exhibit flip-flop kinetics? 7. Why is the tmax for the oral tablets longer than that for the oral solution? 8. What is the plasma concentration 8 hours after administration of the oral solution and oral tablets? 9. How long does it take for the drug to be completely absorbed and eliminated?