MICROPROCESSOR-PROGRAMMED INFUSION OF THEOPHYLLINE RAPIDLY ATTAINED EXPECTED STEADY-STATE LEVEL IN RABBIT PLASMA

A self-made microprocessor-programmed (two-compartmental model) infusi on controller was connected with an infusion pump, which achieved an e xpected steady-state plasma concentration (C-p55) rapidly (5 T-2(1) al pha) and maintained the level. Theophylline was selected as an example , and its pharmacokinetic parameters of rabbits, expected C-p55, body weight (wt), and infusion time (t) were inputted. The programmed infus ion rate (K-t) was determined by the following equation: (K-t)=C-p55.K -10.V-c.wt {1+[(K-21-beta)/beta]EXP(-K(21)t)} and the predicted value was calculated by the formula: C-(t)=C(p55)X[1-EXP(-alpha t)]l. The ne eded concentration and total volume of drug were automatically shown o n the screen. The drug was automatically infused after pumping, and th e plasma concentration of theophylline was measured by colorimetric me thod. The results showed that the median absolute value of the perform ance error (MAVPE) was 8.3 %. Although T-2(1) beta of theophylline was 6.08 h, the expected C-p55 was attained in only 30 min (5 T-2(1) alph a) after start of infusion and then well maintained.