Posted by Larry Hoover on August 7, 2003, at 8:22:45
In reply to Question about Product Info Sheet, posted by irishcatholic on August 7, 2003, at 7:39:25
> Can someone explain C max and T max?
> thanks!!
> "Food has a significant influence on the bioavailability of XANAX XR Tablets. A high-fat meal given up to 2 hours before dosing with XANAX XR Tablets increased the mean C max by about 25%.The effect of this meal on T max depended on the timing of the meal,with a reduction in T max by about 1/3 for subjects eating immediately before dosing and an increase in T max
> by about 1/3 for subjects eating 1 hour or more after dosing.The extent of exposure (AUC)and elimination half-life (t 1/2 )were not affected by eating."All of these terms refer to points on a graph of blood concentration of the drug vs. time since ingestion.
Cmax is the maximum blood concentration (i.e. the highest point on the curve).
Tmax is the time it took for that peak to appear.
AUC is the area under the curve. By taking the integral for that region, you can determine the the exposure of the individual to the drug. For some drugs, the AUC is decreased with food, so those drugs must be taken on an empty stomach.
For Xanax, high-fat food increases the rate of absorption, (higher Cmax), with the effect greatest by eating just before dosing (reduction in Tmax). Total absorption was unaffected, just the rate.
Lar
poster:Larry Hoover
thread:248873
URL: http://www.dr-bob.org/babble/20030807/msgs/248888.html