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Fig. 10
Prediction of changes in spectral edge frequency for the hypnotic
Alfentanil using neural networks (-) compared with measured data
points (  ) after different infusion rates ( ) in a human subject.
(From Ref. 80.) |
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do have certain disadvantages. They may solve short-term problems of gaining information from complex unfathomable systems but they are still a black box providing little insight into the reasons for such interrelationships [82]. However at this stage, just to know that a relationship between drug levels and a complex activity can exist is enough to spur the scientist into further research to find out more details. Unquestionably, these new approaches will be used in the future for not only kinetics and metabolism, but for all areas of drug development. |
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As can be seen from Figure 7 and Table 4, one of the main assumptions when measuring plasma levels is that this directly reflects concentrations at the receptor site and that the same plasma tissue ratio exists in animals and man. Up until recently, it has not been possible to measure tissue levels without biopsy or sacrificing the animals, which makes human investigations impossible. Now, newer techniques of measuring both drug and activity in situ are being developed that could revolutionize kinetic-dynamic modeling. These include microdialysis and imaging techniques. |
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