422 



8. INHIBITOR DISTRIBUTION IN LIVING ORGANISMS 



where At — the interval between doses and (I)^ is the concentration peak 

 produced by a single dose. The maximal constant level attained will be: 



(I), 



(I). 



(8-31) 



TIME - 



Fig. 8-7. Variation of the inhibitor concentration with time following a single 



administration assuming (I) = (I)oe-*^'. (I)o = 10 mM and k — 0.1. The time 



required for the inhibitor concentration to fall to one-half its initial value is 0.69/^" 



and to one-tenth is 2.3/A;. 



The time required to reach this maximal level would be infinite theoretically 

 but for pratical purposes we can calculate the time required to reach to 

 within 90% of this final concentration [i.e., 90% of the way between (I)^ 

 and (I),„,^]. Substituting 0.1 (!),,+ 0.9 (I),,,,,, for (I), in Eq. 8-19, the fol- 

 lowing general relationship is obtained: 



{n - l)kJt = 2.3 (8-32) 



Since the interval between the first dose and the nth dose is (n — 1) At, the 

 time for the concentration to rise to the 90% level is: 



to., = 2.31k (8-33) 



