Propofol plasma levels in the newborn at the time of delivery depend on the level in maternal plasma, and therefore on the dose used for induction and the time lapsed between the administration of the drug and the delivery of the foetus.

This small study suggests that a once-daily dosing regimen of tobramycin is at least as effective as and is no more and possibly less toxic than the twice-daily regimen. Using a single-dose therapy, peak concentration determination is not necessary, only trough samples should be monitored to ensure levels below 2 microg/ml.

Vigabatrin plasma levels show wide interpatient variability, and co-administration with carbamazepine increases vigabatrin's clearance. While there is no relationship between plasma level and anti-epileptic effect, abnormally high levels of the drug may increase toxicity.

The pharmacokinetics of intravenous caffeine used to measure liver function were evaluated in 20 critically ill patients. Each patient received a single dose of 3.0 mg/kg of caffeine benzoate as a 30-min i.v. infusion. Caffeine serum concentrations were analysed by an enzyme-multiplied immunoassay technique (EMIT). Caffeine pharmacokinetics fitted an open one-compartment model. The mean value for the half-life (t1/2) was 9.46 +/- 4.32 h, the volume of distribution was 0.55 +/- 0.13 l/kg, and the plasma clearance (Cl) was 0.85 +/- 0.44 ml/min/kg. The pharmacokinetics parameters of caffeine in critically ill patients compared with normal volunteers were characterized by a reduction in plasma clearance and prolongation in plasma half-life, whereas the volume of distribution remained unchanged.

Vigabatrin produced a statistically significant increase in the plasma clearance of carbamazepine when the two drugs were given simultaneously.