Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Pk lab 5

624 views

Published on

2 compartments model

Published in: Health & Medicine
  • Be the first to comment

Pk lab 5

  1. 1. Biopharmaceutics and PK Lab 5Calculation of PK parameters usingone and two compartment model: IV bolus. Dr Sameh Rabea
  2. 2. Remember For 1st order kinetic one-compartment the equation will be: Cp= (Cp) 0 e –ktWhere: Cp: Y ; (Cp) 0 : intercept; t: X; k: -slope x 2.303; Slope= (logC2 – logC1)/t2-t1.Or Ke = ln (C1/C2)/t2-t1 The PK model: I.V. Central Ke injection Compartment Out. AUC= Cp0/ Ke Vdc= Dose/ Cp0. t ½= 0.693/ Ke.
  3. 3.  For 1storder kinetic two-compartment the equation will be: Cp= A e –αt + B e –βt Where A: intercept of line 1 and B intercept of line 2; α: distribution rate constant and β: elimination rate constant.
  4. 4.  The PK model: I.V. in Central K12 Peripheral Compartment Compartment inj. K 21 K2Cp0= A + BK2 = Cp0 / ( A/ α + B/ β )K12= A.B (β- α) 2 / Cp0 (A β + B α)K21= A β + B α / Cp0 .
  5. 5.  AUC= A/α + B/β . t ½= 0.693/ β. Vd c= Dose/Cp0= Dose/ A+B. Vd area= Dose/AUC. β Vd ss = Vdc + (K12/K21) Vdc Vd tissue= Vd area – Vdc. Therefore: Vd area> Vd ss > Vdc> Vd tissue. But Vd ss is not affected by elimination, so its represents true volume of distribution. CL = Vdc. Ke or CL= Vdc. Β.
  6. 6. Problem # 1 A patient received 500 mg cefepime I.V bolus injection and numerous blood samples were drawn as the following:
  7. 7. Plotting DataTime (hr) Conc.( µ/ml) 0.5 38.2 1 21.6 2 11.6 4 5.0 8 1.4 12 0.2
  8. 8.  A- Test the order of this data. B- Write your model Calculate as many PK parameter as possible.
  9. 9. Problem # 2 A patient received 300 mg I.V. dose of a drug. Several blood samples were collected and the following plasma concentrations were obtained:
  10. 10. Plotting DataTime (hr) Conc.( µ/ml) 0.2 5.6 0.4 4.6 0.6 3.8 0.8 3.2 1 2.8 2 1.8 3 1.35 4 1.2 5 1.06 24 0.0
  11. 11.  Test the order of this data. Write the model. Calculate PK parameters.
  12. 12. Problem # 3 A patient received 350 mg I.V bolus dose of drug. Several blood samples were collected and the following plasma concentrations were obtained:
  13. 13. Plotting DataTime (hr) Conc. (µg/ml) 0.5 20.8 1 13.8 1.5 10 2 7.9 3 5.3 6 2.9 8 2 10 1.4
  14. 14.  A- Draw diagrammatic presentation describing PK model , and write your equation.
  15. 15.  Calculate the following PK parameters: A: B: α: β (Ke): t1/2 : AUC: Vdc: Vd area:

×