Bioequivalence and Bioavailability Forum

Hi all,

Can someone explain to me the following (or a kick in the butt if this is too simple?) from Csizmadia & Endrenyi? I don't have the Gibaldi PK book on hand (they referenced it from his book).

Basis of the Proposed Methods. If a drug exhibits first-order absorption with one-exponential disposition and the absorption (ka) and elimination (k) rate constants are equal, then the plasma concentration (C) depends on time according to:

C=kAtexp(-kt), where A=FD/V

For the above model, k=1/Tmax, where Tmax is the time when the plasma concentration reaches maximum.

How did he arrive to k=1/Tmax?

Thanks
John
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Csizmadia F, Endrenyi L. Model-Independent Estimation of Lag Times with First-Order Absorption and Disposition. J Pharm Sci Vol. 87:5. May 1998