- On 20 Jan 2003 at 10:15:46, "Gregg Timony" (gtimony.-a-.conformacorp.com) sent the message

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The following message was posted to: PharmPK

Hello All,

To calculate the amount of drug in a peripheral compartment vs

time for a 2 compartment open model

(IV bolus to central with elimination only from central) I've

used:

mass in peripheral compartment = K12*Dose(alpha-beta) x

(e-beta x t - e-alpha x t)

I'm working with a compound that shows distinct 3 compartment

behavior following IV bolus dosing and

I haven't been able to work out the analogous equations for

compartments 2 and 3.

Assuming central compartment dosing, elimination only from the

central compartment, with compartment

1 centrally positioned with connectivity to compartments 2 and

3 (k12/k21, K13/k31)........

can someone provide equations for the mass in compartments 2

and 3 over time?

Appreciate Your Assistance,

Gregg

Gregg A. Timony, M.S.

Head, Toxicology and ADME

Preclinical Development

Conforma Therapeutics

9393 Towne Centre Drive, Suite 240

San Diego, CA 92121

(858) 795-0124

[Do you mean

mass in peripheral compartment = (K12*Dose/(alpha-beta)) x (e-beta x t

- e-alpha x t)

for the two compartment model.

The Laplace of the amount in compartment 3 is:

L(X3) = k13*(s+k21)*Dose/((s+alpha)*(s+beta)*(s+gamma))

The fingerprint method will help with the back-transform

http://www.boomer.org/c/p3/c07/c0702.html

- db]

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