Module 5. Species differences in pharmacokinetics (Cats are not small dogs).

Objectives

Having completed this exercise and based on pharmacokinetic constants and data, students should be able to:

Significance

Pharmacokinetic parameters and dosage recommendations are taken from the USP Veterinary Drug Monograph "Chloramphenicol" (http://www.aavpt.org/associations/12658/files/chloramphenicol.pdf)

The original dose recommendations for chloramphenicol administration in cats were the same as dogs (50 mg/kg, q8H). Given in this fashion, chloramphenicol produced a greater incidence of side effects (depressed white cell count, anorexia, etc.) in cats than dogs. The recommended cat dosage was subsequently revised to 13 - 20 mg/kg q12H.

Exercise

Download chloramphenicol.xlsx, (the worksheet for this module). Depending on the security setting of your computer, you may have to "enable editing" in order to make the changes suggested by the exercise.

Pharmacokinetic variables for the "Dog" simulation values published for dogs. Pharmacokinetic variables for the "Cat" simulation are values published for cats.

Doses and intervals for both simulations are set to 50 mg/kg q8H (typical dog dosing regimen).

Target concentrations

Manipulate the dosage

Step 1: Before you make changes, review pharmacokinetic variables, calculated values and steady state calculated values.

Step 2: Alter the dosage for cats

Inspect

Calculated values

Step 1 & 2:

Steady-State Concentrations (for repeated doses during therapy).

Step 1:

Step 2:

Graphs

Step 1:

Step 2:

Assess