In vivo simulation of human pharmacokinetics in the rabbit.

The evaluation of drugs in vivo is often based on experimental models using small animals such as mice, rats and rabbits. However, these models could be improved to correspond more closely to the human situation if the pharmacokinetics of the drugs tested in animals were similar to that observed in humans. The use of a computer-controlled pump allowing an adequate flow of tobramycin and amikacin to be infused into rabbits enabled us to simulate the human pharmacokinetics of these antibiotics in vivo in this study. The function defining the rate of infusion required to perform the simulation of an intravenous bolus was first determined generally and symbolically for linear pharmacokinetic models independently from the number of compartments involved. The practical simulation of a decreasing monoexponential serum profile with a half-life of 2 h (one-compartment model for the human pharmacokinetics of aminoglycosides) was then studied for tobramycin and amikacin on the basis of a two-compartment model in the animal. The kinetics obtained had an apparent elimination half-life of 1.97 and 1.86 h, respectively. Linearity of the semilogarithmic regressions of the profiles obtained was quite sound. Finally, an a posteriori analysis of the pharmacokinetic model and its parameters is proposed on the basis of the results obtained after simulation.

Ambulatory monitoring of blood pressure disturbs sleep and raises systolic pressure at night in patients suspected of suffering from sleep-disordered breathing.

1. The aim of the study was to assess the effect of ambulatory monitoring of blood pressure on sleep and on blood pressure in middle-aged patients. 2. Nine consecutive patients (seven men, two women; mean age 57 years) complaining of snoring and various degrees of excessive daytime somnolence were studied. Five patients were normotensive and four were being treated for hypertension. During one night standard laboratory polysomnography was performed with monitoring of blood pressure by a silent ambulatory monitor and continuous infrared blood pressure by photoplethysmography. 3. Ambulatory blood pressure significantly disturbs sleep architecture, causing EEG arousals in 64% of measurements, and induces a significant rise in blood pressure during systolic pressure measurement by the ambulatory monitor (rise in systolic pressure, 13.7 +/- 15.9 mmHg, P < 0.001; rise in diastolic pressure, 3.7 +/- 8.2 mmHg, P < 0.01). At the time of diastolic measurement, blood pressure had returned to the preinflation value. The rise in systolic blood pressure was higher when an arousal was associated with cuff inflation (P < 0.001). This rise in blood pressure is probably the consequence of sympathetic nervous system activation. 4. We conclude that ambulatory blood pressure recordings of systolic blood pressure during sleep should be interpreted with caution as systolic blood pressure may be significantly increased in patients suspected of suffering from sleep-disordered breathing.