Pharmacokinetics of intravenous and oral midazolam in plasma and saliva in humans: usefulness of saliva as matrix for CYP3A phenotyping.

Aims: To compare midazolam kinetics between plasma and saliva and to find out whether saliva is suitable for CYP3A phenotyping.

Methods: This was a two way cross-over study in eight subjects treated with 2 mg midazolam IV or 7.5 mg orally under basal conditions and after CYP3A induction with rifampicin.

Pharmacokinetics of midazolam and metabolites in a patient with refractory status epilepticus treated with extraordinary doses of midazolam.

The authors present a patient with refractory epilepsy who was treated with very high doses (up to 4 mg/min) of intravenous midazolam, phenytoin, carbamazepine, and other antiepileptics. Because it was known from the literature that the half-life of midazolam can increase at high dosage, the kinetics of midazolam (MDZ), 1'-hydroxymidazolam, and 4-hydroxymidazolam were assessed at steady state (dosage 1 mg/min) and after stopping treatment. Total body clearance of MDZ (33 L/kg) and intrinsic hepatic clearance (19 mL/min/kg) at steady state were both five to 10 times higher than after normal therapeutic doses, demonstrating hepatic cytochrome (CYP) 3A induction.

Determination of midazolam and its hydroxy metabolites in human plasma and oral fluid by liquid chromatography/electrospray ionization ion trap tandem mass spectrometry.

Midazolam (MDZ), a short-acting benzodiazepine, is a widely accepted probe drug for CYP3A phenotyping. Published methods for its analysis have used either therapeutic doses of MDZ, or, if employing lower doses, were mostly unable to quantify the two hydroxy metabolites. In the present study, a sensitive and specific liquid chromatography/electrospray ionization tandem mass spectrometry method was developed and validated for the quantitative determination of MDZ and two of its metabolites (1'-hydroxymidazolam (1'-OHMDZ) and 4-hydroxymidazolam (4-OHMDZ)) in human plasma and oral fluid.