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>On Tue 18 Feb, Mary Rack wrote: >> Brian - half-life is a concept used whenever there is a condition called "exponential decay". >> Mary >> cg for mom 75/6 >> [log in to unmask] >> >> >Thanks Mary, you have put your finger on the part that ws botherng me: That is >that Half-life definitions are really only appropriate to situations where a >form of exponential decay is going on, such as in radioactivity. To apply the >term to the CR tablet, where the designers have deliberately set out to >achieve a constant rate of throughput seems to me to be a meaningless concept. > >Regards, >-- >Brian Collins > > Brian and Mary, I telephoned the manufacturers of Sinemet on this point and also because they had not sent me the data I had requested from them before Christmas. Seeking clarification on the "half-life", I was told that the "exponential decay rate" referred to the drug once it was in the blood plasma. From this, I conclude that standard Sinemet will quickly reach its peak level and then follow the exponential half-life decay described. Sinemet CR will, however, deliver its designed dosage evenly per hour until exhausted. At this point, the half-life decay rate will again come into play for the drug remaining in the blood. All this is the "ideal" and does not take into account all the variables that confound our best plans! If the data I receive brings up any further points of interest I will let you know. Regards, Ernie Peters <[log in to unmask]>