Please complete the online exercise. OPTIONAL‐Please participate in the online discussion forum.
7.4 Volume of Distribution I One‐compartment model video Please watch the online video (5 minutes 33 seconds). A condensed summary of this video can be found in the Video summary page. OPTIONAL‐Please participate in the online discussion forum.
Detailing the one‐compartment model Background: The one‐compartment model is a pharmacokinetic model that describes the fluid that contains a drug in the body as a single volume of plasma. Although simple, the one‐compartment model can be interpreted usefully to understand a drug's behavior. Instructions: Read the passage below concerning the Vd of ranitidine. Learning Goal: To understand how to make sense of the numerical value of a drug's Vd based on the one‐compartment model. Ranitidine is a drug that can be used to treat heartburn, acid reflux, and occasionally ulcers. The Vd of ranitidine is 1.4 L/kg, or 98 L for a 70‐kg patient. To be clear, that is 98 L hypothetical volume of plasma. The volume is hypothetical because a 70‐kg patient only has an actual plasma volume of 2.7 L (54% of the volume of whole blood).
While ranitidine is normally administered orally, IV dosages of 25 mg are available. When administered by IV, Do = 25 mg. We know Vd is 98 L. From this information we can calculate Cpo to be 0.255 mg/L.
Published on May 6, 2014